Merge bitcoin-core/secp256k1#1465: release: prepare for 0.4.1

672053d801 release: prepare for 0.4.1 (Jonas Nick)

Pull request description:

ACKs for top commit:
  sipa:
    ACK 672053d801
  real-or-random:
    ACK 672053d801
  hebasto:
    ACK 672053d801

Tree-SHA512: de78fd4588061ffc9b869d86c6d639dce06ed215c0614a888827054014c073a97b106268e5d5773967f9407c70ddc0f27326ee9c858dce5d52af7f33d2d46b69

.cirrus.yml

@@ -1,6 +1,9 @@
 env:
+  ### cirrus config
+  CIRRUS_CLONE_DEPTH: 1
   ### compiler options
   HOST:
+  WRAPPER_CMD:
   # Specific warnings can be disabled with -Wno-error=foo.
   # -pedantic-errors is not equivalent to -Werror=pedantic and thus not implied by -Werror according to the GCC manual.
   WERROR_CFLAGS: -Werror -pedantic-errors
@@ -18,27 +21,25 @@ env:
   ECDH: no
   RECOVERY: no
   SCHNORRSIG: no
+  ELLSWIFT: no
   ### test options
   SECP256K1_TEST_ITERS:
   BENCH: yes
   SECP256K1_BENCH_ITERS: 2
-  CTIMETEST: yes
+  CTIMETESTS: yes
   # Compile and run the tests
   EXAMPLES: yes
 
-# https://cirrus-ci.org/pricing/#compute-credits
-credits_snippet: &CREDITS
-  # Don't use any credits for now.
-  use_compute_credits: false
-
 cat_logs_snippet: &CAT_LOGS
   always:
     cat_tests_log_script:
       - cat tests.log || true
+    cat_noverify_tests_log_script:
+      - cat noverify_tests.log || true
     cat_exhaustive_tests_log_script:
       - cat exhaustive_tests.log || true
-    cat_valgrind_ctime_test_log_script:
-      - cat valgrind_ctime_test.log || true
+    cat_ctime_tests_log_script:
+      - cat ctime_tests.log || true
     cat_bench_log_script:
       - cat bench.log || true
     cat_config_log_script:
@@ -48,330 +49,47 @@ cat_logs_snippet: &CAT_LOGS
     cat_ci_env_script:
       - env
 
-merge_base_script_snippet: &MERGE_BASE
-  merge_base_script:
-    - if [ "$CIRRUS_PR" = "" ]; then exit 0; fi
-    - git fetch $CIRRUS_REPO_CLONE_URL $CIRRUS_BASE_BRANCH
-    - git config --global user.email "ci@ci.ci"
-    - git config --global user.name "ci"
-    - git merge FETCH_HEAD  # Merge base to detect silent merge conflicts
-
-linux_container_snippet: &LINUX_CONTAINER
-  container:
-    dockerfile: ci/linux-debian.Dockerfile
-    # Reduce number of CPUs to be able to do more builds in parallel.
-    cpu: 1
-    # Gives us more CPUs for free if they're available.
-    greedy: true
-    # More than enough for our scripts.
-    memory: 1G
-
-task:
-  name: "x86_64: Linux (Debian stable)"
-  << : *LINUX_CONTAINER
-  matrix: &ENV_MATRIX
-    - env: {WIDEMUL:  int64,  RECOVERY: yes}
-    - env: {WIDEMUL:  int64,                 ECDH: yes, SCHNORRSIG: yes}
-    - env: {WIDEMUL: int128}
-    - env: {WIDEMUL: int128_struct}
-    - env: {WIDEMUL: int128,  RECOVERY: yes,            SCHNORRSIG: yes}
-    - env: {WIDEMUL: int128,                 ECDH: yes, SCHNORRSIG: yes}
-    - env: {WIDEMUL: int128,  ASM: x86_64}
-    - env: {                  RECOVERY: yes,            SCHNORRSIG: yes}
-    - env: {BUILD: distcheck, WITH_VALGRIND: no, CTIMETEST: no, BENCH: no}
-    - env: {CPPFLAGS: -DDETERMINISTIC}
-    - env: {CFLAGS: -O0, CTIMETEST: no}
-    - env: { ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
-    - env: { ECMULTGENPRECISION: 8, ECMULTWINDOW: 4 }
-  matrix:
-    - env:
-        CC: gcc
-    - env:
-        CC: clang
-  << : *MERGE_BASE
+linux_arm64_container_snippet: &LINUX_ARM64_CONTAINER
+  env_script:
+    - env | tee /tmp/env
+  build_script:
+    - DOCKER_BUILDKIT=1 docker build --file "ci/linux-debian.Dockerfile" --tag="ci_secp256k1_arm"
+    - docker image prune --force  # Cleanup stale layers
   test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
+    - docker run --rm --mount "type=bind,src=./,dst=/ci_secp256k1" --env-file /tmp/env --replace --name "ci_secp256k1_arm" "ci_secp256k1_arm" bash -c "cd /ci_secp256k1/ && ./ci/ci.sh"
 
 task:
-  name: "i686: Linux (Debian stable)"
-  << : *LINUX_CONTAINER
-  env:
-    HOST: i686-linux-gnu
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-  matrix:
-    - env:
-        CC: i686-linux-gnu-gcc
-    - env:
-        CC: clang --target=i686-pc-linux-gnu -isystem /usr/i686-linux-gnu/include
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  name: "arm64: macOS Ventura"
-  macos_instance:
-    image: ghcr.io/cirruslabs/macos-ventura-base:latest
-  env:
-    HOMEBREW_NO_AUTO_UPDATE: 1
-    HOMEBREW_NO_INSTALL_CLEANUP: 1
-    # Cirrus gives us a fixed number of 4 virtual CPUs. Not that we even have that many jobs at the moment...
-    MAKEFLAGS: -j5
-  matrix:
-    << : *ENV_MATRIX
-  env:
-    ASM: no
-    WITH_VALGRIND: no
-    CTIMETEST: no
-  matrix:
-    - env:
-        CC: gcc
-    - env:
-        CC: clang
-  brew_script:
-    - brew install automake libtool gcc
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-  << : *CREDITS
-
-task:
-  name: "s390x (big-endian): Linux (Debian stable, QEMU)"
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: qemu-s390x
-    SECP256K1_TEST_ITERS: 16
-    HOST: s390x-linux-gnu
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-  << : *MERGE_BASE
-  test_script:
-    # https://sourceware.org/bugzilla/show_bug.cgi?id=27008
-    - rm /etc/ld.so.cache
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  name: "ARM32: Linux (Debian stable, QEMU)"
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: qemu-arm
-    SECP256K1_TEST_ITERS: 16
-    HOST: arm-linux-gnueabihf
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-  matrix:
-    - env: {}
-    - env: {EXPERIMENTAL: yes, ASM: arm}
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  name: "ARM64: Linux (Debian stable, QEMU)"
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: qemu-aarch64
-    SECP256K1_TEST_ITERS: 16
-    HOST: aarch64-linux-gnu
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  name: "ppc64le: Linux (Debian stable, QEMU)"
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: qemu-ppc64le
-    SECP256K1_TEST_ITERS: 16
-    HOST: powerpc64le-linux-gnu
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: wine
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-  matrix:
-    - name: "x86_64 (mingw32-w64): Windows (Debian stable, Wine)"
-      env:
-        HOST: x86_64-w64-mingw32
-    - name: "i686 (mingw32-w64): Windows (Debian stable, Wine)"
-      env:
-        HOST: i686-w64-mingw32
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  << : *LINUX_CONTAINER
-  env:
-    WRAPPER_CMD: wine
-    WERROR_CFLAGS: -WX
-    WITH_VALGRIND: no
-    ECDH: yes
-    RECOVERY: yes
-    EXPERIMENTAL: yes
-    SCHNORRSIG: yes
-    CTIMETEST: no
-    # Use a MinGW-w64 host to tell ./configure we're building for Windows.
-    # This will detect some MinGW-w64 tools but then make will need only
-    # the MSVC tools CC, AR and NM as specified below.
-    HOST: x86_64-w64-mingw32
-    CC: /opt/msvc/bin/x64/cl
-    AR: /opt/msvc/bin/x64/lib
-    NM: /opt/msvc/bin/x64/dumpbin -symbols -headers
-    # Set non-essential options that affect the CLI messages here.
-    # (They depend on the user's taste, so we don't want to set them automatically in configure.ac.)
-    CFLAGS: -nologo -diagnostics:caret
-    LDFLAGS: -XCClinker -nologo -XCClinker -diagnostics:caret
-  matrix:
-    - name: "x86_64 (MSVC): Windows (Debian stable, Wine)"
-    - name: "x86_64 (MSVC): Windows (Debian stable, Wine, int128_struct)"
-      env:
-        WIDEMUL: int128_struct
-    - name: "x86_64 (MSVC): Windows (Debian stable, Wine, int128_struct with __(u)mulh)"
-      env:
-        WIDEMUL: int128_struct
-        CPPFLAGS: -DSECP256K1_MSVC_MULH_TEST_OVERRIDE
-    - name: "i686 (MSVC): Windows (Debian stable, Wine)"
-      env:
-        HOST: i686-w64-mingw32
-        CC: /opt/msvc/bin/x86/cl
-        AR: /opt/msvc/bin/x86/lib
-        NM: /opt/msvc/bin/x86/dumpbin -symbols -headers
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-# Sanitizers
-task:
-  << : *LINUX_CONTAINER
+  name: "ARM64: Linux (Debian stable)"
+  persistent_worker:
+    labels:
+      type: arm64
   env:
     ECDH: yes
     RECOVERY: yes
     SCHNORRSIG: yes
-    CTIMETEST: no
+    ELLSWIFT: yes
   matrix:
-    - name: "Valgrind (memcheck)"
-      container:
-        cpu: 2
-      env:
-        # The `--error-exitcode` is required to make the test fail if valgrind found errors, otherwise it'll return 0 (https://www.valgrind.org/docs/manual/manual-core.html)
-        WRAPPER_CMD: "valgrind --error-exitcode=42"
-        SECP256K1_TEST_ITERS: 2
-    - name: "UBSan, ASan, LSan"
-      container:
-        memory: 2G
-      env:
-        CFLAGS: "-fsanitize=undefined,address -g"
-        UBSAN_OPTIONS: "print_stacktrace=1:halt_on_error=1"
-        ASAN_OPTIONS: "strict_string_checks=1:detect_stack_use_after_return=1:detect_leaks=1"
-        LSAN_OPTIONS: "use_unaligned=1"
-        SECP256K1_TEST_ITERS: 32
-  # Try to cover many configurations with just a tiny matrix.
-  matrix:
-    - env:
-        ASM: auto
-    - env:
-        ASM: no
-        ECMULTGENPRECISION: 2
-        ECMULTWINDOW: 2
-  matrix:
-    - env:
-        CC: clang
-    - env:
-        HOST: i686-linux-gnu
-        CC: i686-linux-gnu-gcc
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
+     # Currently only gcc-snapshot, the other compilers are tested on GHA with QEMU
+     - env: { CC: 'gcc-snapshot' }
+  << : *LINUX_ARM64_CONTAINER
   << : *CAT_LOGS
 
-# Memory sanitizers
 task:
-  << : *LINUX_CONTAINER
-  name: "MSan"
+  name: "ARM64: Linux (Debian stable), Valgrind"
+  persistent_worker:
+    labels:
+      type: arm64
   env:
     ECDH: yes
     RECOVERY: yes
     SCHNORRSIG: yes
-    CTIMETEST: no
-    CC: clang
-    SECP256K1_TEST_ITERS: 32
-    ASM: no
-  container:
-    memory: 2G
+    ELLSWIFT: yes
+    WRAPPER_CMD: 'valgrind --error-exitcode=42'
+    SECP256K1_TEST_ITERS: 2
   matrix:
-    - env:
-        CFLAGS: "-fsanitize=memory -g"
-    - env:
-        ECMULTGENPRECISION: 2
-        ECMULTWINDOW: 2
-        CFLAGS: "-fsanitize=memory -g -O3"
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
+     - env: { CC: 'gcc' }
+     - env: { CC: 'clang' }
+     - env: { CC: 'gcc-snapshot' }
+     - env: { CC: 'clang-snapshot' }
+  << : *LINUX_ARM64_CONTAINER
   << : *CAT_LOGS
-
-task:
-  name: "C++ -fpermissive (entire project)"
-  << : *LINUX_CONTAINER
-  env:
-    CC: g++
-    CFLAGS: -fpermissive -g
-    CPPFLAGS: -DSECP256K1_CPLUSPLUS_TEST_OVERRIDE
-    WERROR_CFLAGS:
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-  << : *MERGE_BASE
-  test_script:
-    - ./ci/cirrus.sh
-  << : *CAT_LOGS
-
-task:
-  name: "C++ (public headers)"
-  << : *LINUX_CONTAINER
-  test_script:
-    - g++ -Werror include/*.h
-    - clang -Werror -x c++-header include/*.h
-    - /opt/msvc/bin/x64/cl.exe -c -WX -TP include/*.h
-
-task:
-  name: "sage prover"
-  << : *LINUX_CONTAINER
-  test_script:
-    - cd sage
-    - sage prove_group_implementations.sage

.github/actions/install-homebrew-valgrind/action.yml

@@ -0,0 +1,33 @@
+name: "Install Valgrind"
+description: "Install Homebrew's Valgrind package and cache it."
+runs:
+  using: "composite"
+  steps:
+    - run: |
+        brew tap LouisBrunner/valgrind
+        brew fetch --HEAD LouisBrunner/valgrind/valgrind
+        echo "CI_HOMEBREW_CELLAR_VALGRIND=$(brew --cellar valgrind)" >> "$GITHUB_ENV"
+      shell: bash
+
+    - run: |
+        sw_vers > valgrind_fingerprint
+        brew --version >> valgrind_fingerprint
+        git -C "$(brew --cache)/valgrind--git" rev-parse HEAD >> valgrind_fingerprint
+        cat valgrind_fingerprint
+      shell: bash
+
+    - uses: actions/cache@v3
+      id: cache
+      with:
+        path: ${{ env.CI_HOMEBREW_CELLAR_VALGRIND }}
+        key: ${{ github.job }}-valgrind-${{ hashFiles('valgrind_fingerprint') }}
+
+    - if: steps.cache.outputs.cache-hit != 'true'
+      run: |
+        brew install --HEAD LouisBrunner/valgrind/valgrind
+      shell: bash
+
+    - if: steps.cache.outputs.cache-hit == 'true'
+      run: |
+        brew link valgrind
+      shell: bash

.github/actions/run-in-docker-action/action.yml

@@ -0,0 +1,49 @@
+name: 'Run in Docker with environment'
+description: 'Run a command in a Docker container, while passing explicitly set environment variables into the container.'
+inputs:
+  dockerfile:
+    description: 'A Dockerfile that defines an image'
+    required: true
+  tag:
+    description: 'A tag of an image'
+    required: true
+  command:
+    description: 'A command to run in a container'
+    required: false
+    default: ./ci/ci.sh
+runs:
+  using: "composite"
+  steps:
+    - uses: docker/setup-buildx-action@v3
+
+    - uses: docker/build-push-action@v5
+      id: main_builder
+      continue-on-error: true
+      with:
+        context: .
+        file: ${{ inputs.dockerfile }}
+        tags: ${{ inputs.tag }}
+        load: true
+        cache-from: type=gha
+
+    - uses: docker/build-push-action@v5
+      id: retry_builder
+      if: steps.main_builder.outcome == 'failure'
+      with:
+        context: .
+        file: ${{ inputs.dockerfile }}
+        tags: ${{ inputs.tag }}
+        load: true
+        cache-from: type=gha
+
+    - # Tell Docker to pass environment variables in `env` into the container.
+      run: >
+        docker run \
+          $(echo '${{ toJSON(env) }}' | jq -r 'keys[] | "--env \(.) "') \
+          --volume ${{ github.workspace }}:${{ github.workspace }} \
+          --workdir ${{ github.workspace }} \
+          ${{ inputs.tag }} bash -c "
+            git config --global --add safe.directory ${{ github.workspace }}
+            ${{ inputs.command }}
+          "
+      shell: bash

.github/workflows/ci.yml

@@ -0,0 +1,806 @@
+name: CI
+on:
+  pull_request:
+  push:
+    branches:
+      - '**'
+    tags-ignore:
+      - '**'
+
+concurrency:
+  group: ${{ github.event_name != 'pull_request' && github.run_id || github.ref }}
+  cancel-in-progress: true
+
+env:
+  ### compiler options
+  HOST:
+  WRAPPER_CMD:
+  # Specific warnings can be disabled with -Wno-error=foo.
+  # -pedantic-errors is not equivalent to -Werror=pedantic and thus not implied by -Werror according to the GCC manual.
+  WERROR_CFLAGS: '-Werror -pedantic-errors'
+  MAKEFLAGS: '-j4'
+  BUILD: 'check'
+  ### secp256k1 config
+  ECMULTWINDOW: 'auto'
+  ECMULTGENPRECISION: 'auto'
+  ASM: 'no'
+  WIDEMUL: 'auto'
+  WITH_VALGRIND: 'yes'
+  EXTRAFLAGS:
+  ### secp256k1 modules
+  EXPERIMENTAL: 'no'
+  ECDH: 'no'
+  RECOVERY: 'no'
+  SCHNORRSIG: 'no'
+  ELLSWIFT: 'no'
+  ### test options
+  SECP256K1_TEST_ITERS:
+  BENCH: 'yes'
+  SECP256K1_BENCH_ITERS: 2
+  CTIMETESTS: 'yes'
+  # Compile and run the examples.
+  EXAMPLES: 'yes'
+
+jobs:
+  docker_cache:
+    name: "Build Docker image"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+        with:
+          # See: https://github.com/moby/buildkit/issues/3969.
+          driver-opts: |
+            network=host
+
+      - name: Build container
+        uses: docker/build-push-action@v5
+        with:
+          file: ./ci/linux-debian.Dockerfile
+          tags: linux-debian-image
+          cache-from: type=gha
+          cache-to: type=gha,mode=min
+
+  linux_debian:
+    name: "x86_64: Linux (Debian stable)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars: { WIDEMUL: 'int64',  RECOVERY: 'yes' }
+          - env_vars: { WIDEMUL: 'int64',                   ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - env_vars: { WIDEMUL: 'int128' }
+          - env_vars: { WIDEMUL: 'int128_struct',                                           ELLSWIFT: 'yes' }
+          - env_vars: { WIDEMUL: 'int128', RECOVERY: 'yes',              SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - env_vars: { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes' }
+          - env_vars: { WIDEMUL: 'int128', ASM: 'x86_64',                                   ELLSWIFT: 'yes' }
+          - env_vars: {                    RECOVERY: 'yes',              SCHNORRSIG: 'yes' }
+          - env_vars: { CTIMETESTS: 'no',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', CPPFLAGS: '-DVERIFY' }
+          - env_vars: { BUILD: 'distcheck', WITH_VALGRIND: 'no', CTIMETESTS: 'no', BENCH: 'no' }
+          - env_vars: { CPPFLAGS: '-DDETERMINISTIC' }
+          - env_vars: { CFLAGS: '-O0', CTIMETESTS: 'no' }
+          - env_vars: { CFLAGS: '-O1',     RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - env_vars: { ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
+          - env_vars: { ECMULTGENPRECISION: 8, ECMULTWINDOW: 4 }
+        cc:
+          - 'gcc'
+          - 'clang'
+          - 'gcc-snapshot'
+          - 'clang-snapshot'
+
+    env:
+      CC: ${{ matrix.cc }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  i686_debian:
+    name: "i686: Linux (Debian stable)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        cc:
+          - 'i686-linux-gnu-gcc'
+          - 'clang --target=i686-pc-linux-gnu -isystem /usr/i686-linux-gnu/include'
+
+    env:
+      HOST: 'i686-linux-gnu'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CC: ${{ matrix.cc }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  s390x_debian:
+    name: "s390x (big-endian): Linux (Debian stable, QEMU)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    env:
+      WRAPPER_CMD: 'qemu-s390x'
+      SECP256K1_TEST_ITERS: 16
+      HOST: 's390x-linux-gnu'
+      WITH_VALGRIND: 'no'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  arm32_debian:
+    name: "ARM32: Linux (Debian stable, QEMU)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars: {}
+          - env_vars: { EXPERIMENTAL: 'yes', ASM: 'arm32' }
+
+    env:
+      WRAPPER_CMD: 'qemu-arm'
+      SECP256K1_TEST_ITERS: 16
+      HOST: 'arm-linux-gnueabihf'
+      WITH_VALGRIND: 'no'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  arm64_debian:
+    name: "ARM64: Linux (Debian stable, QEMU)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    env:
+      WRAPPER_CMD: 'qemu-aarch64'
+      SECP256K1_TEST_ITERS: 16
+      HOST: 'aarch64-linux-gnu'
+      WITH_VALGRIND: 'no'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars: { } # gcc
+          - env_vars: # clang
+              CC: 'clang --target=aarch64-linux-gnu'
+          - env_vars: # clang-snapshot
+              CC: 'clang-snapshot --target=aarch64-linux-gnu'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  ppc64le_debian:
+    name: "ppc64le: Linux (Debian stable, QEMU)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    env:
+      WRAPPER_CMD: 'qemu-ppc64le'
+      SECP256K1_TEST_ITERS: 16
+      HOST: 'powerpc64le-linux-gnu'
+      WITH_VALGRIND: 'no'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  valgrind_debian:
+    name: "Valgrind (memcheck)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars: { CC: 'clang',                                      ASM: 'auto' }
+          - env_vars: { CC: 'i686-linux-gnu-gcc', HOST: 'i686-linux-gnu', ASM: 'auto' }
+          - env_vars: { CC: 'clang',                                      ASM: 'no', ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
+          - env_vars: { CC: 'i686-linux-gnu-gcc', HOST: 'i686-linux-gnu', ASM: 'no', ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
+
+    env:
+      # The `--error-exitcode` is required to make the test fail if valgrind found errors,
+      # otherwise it will return 0 (https://www.valgrind.org/docs/manual/manual-core.html).
+      WRAPPER_CMD: 'valgrind --error-exitcode=42'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+      SECP256K1_TEST_ITERS: 2
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  sanitizers_debian:
+    name: "UBSan, ASan, LSan"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars: { CC: 'clang',                                      ASM: 'auto' }
+          - env_vars: { CC: 'i686-linux-gnu-gcc', HOST: 'i686-linux-gnu', ASM: 'auto' }
+          - env_vars: { CC: 'clang',                                      ASM: 'no', ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
+          - env_vars: { CC: 'i686-linux-gnu-gcc', HOST: 'i686-linux-gnu', ASM: 'no', ECMULTGENPRECISION: 2, ECMULTWINDOW: 2 }
+
+    env:
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+      CFLAGS: '-fsanitize=undefined,address -g'
+      UBSAN_OPTIONS: 'print_stacktrace=1:halt_on_error=1'
+      ASAN_OPTIONS: 'strict_string_checks=1:detect_stack_use_after_return=1:detect_leaks=1'
+      LSAN_OPTIONS: 'use_unaligned=1'
+      SECP256K1_TEST_ITERS: 32
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  msan_debian:
+    name: "MSan"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars:
+              CFLAGS: '-fsanitize=memory -fsanitize-recover=memory -g'
+          - env_vars:
+              ECMULTGENPRECISION: 2
+              ECMULTWINDOW: 2
+              CFLAGS: '-fsanitize=memory -fsanitize-recover=memory -g -O3'
+
+    env:
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'yes'
+      CC: 'clang'
+      SECP256K1_TEST_ITERS: 32
+      ASM: 'no'
+      WITH_VALGRIND: 'no'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  mingw_debian:
+    name: ${{ matrix.configuration.job_name }}
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    env:
+      WRAPPER_CMD: 'wine'
+      WITH_VALGRIND: 'no'
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'no'
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - job_name: 'x86_64 (mingw32-w64): Windows (Debian stable, Wine)'
+            env_vars:
+              HOST: 'x86_64-w64-mingw32'
+          - job_name: 'i686 (mingw32-w64): Windows (Debian stable, Wine)'
+            env_vars:
+              HOST: 'i686-w64-mingw32'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  macos-native:
+    name: "x86_64: macOS Monterey"
+    # See: https://github.com/actions/runner-images#available-images.
+    runs-on: macos-12 # Use M1 once available https://github.com/github/roadmap/issues/528
+
+    env:
+      CC: 'clang'
+      HOMEBREW_NO_AUTO_UPDATE: 1
+      HOMEBREW_NO_INSTALL_CLEANUP: 1
+
+    strategy:
+      fail-fast: false
+      matrix:
+        env_vars:
+          - { WIDEMUL: 'int64',  RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - { WIDEMUL: 'int128_struct', ECMULTGENPRECISION: 2, ECMULTWINDOW: 4 }
+          - { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', CC: 'gcc' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes',            WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', CC: 'gcc', WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', CPPFLAGS: '-DVERIFY', CTIMETESTS: 'no' }
+          - BUILD: 'distcheck'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Homebrew packages
+        run: |
+          brew install automake libtool gcc
+          ln -s $(brew --prefix gcc)/bin/gcc-?? /usr/local/bin/gcc
+
+      - name: Install and cache Valgrind
+        uses: ./.github/actions/install-homebrew-valgrind
+
+      - name: CI script
+        env: ${{ matrix.env_vars }}
+        run: ./ci/ci.sh
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  win64-native:
+    name: ${{ matrix.configuration.job_name }}
+    # See: https://github.com/actions/runner-images#available-images.
+    runs-on: windows-2022
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - job_name: 'x64 (MSVC): Windows (VS 2022, shared)'
+            cmake_options: '-A x64 -DBUILD_SHARED_LIBS=ON'
+          - job_name: 'x64 (MSVC): Windows (VS 2022, static)'
+            cmake_options: '-A x64 -DBUILD_SHARED_LIBS=OFF'
+          - job_name: 'x64 (MSVC): Windows (VS 2022, int128_struct)'
+            cmake_options: '-A x64 -DSECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY=int128_struct'
+          - job_name: 'x64 (MSVC): Windows (VS 2022, int128_struct with __(u)mulh)'
+            cmake_options: '-A x64 -DSECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY=int128_struct'
+            cpp_flags: '/DSECP256K1_MSVC_MULH_TEST_OVERRIDE'
+          - job_name: 'x86 (MSVC): Windows (VS 2022)'
+            cmake_options: '-A Win32'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Generate buildsystem
+        run: cmake -E env CFLAGS="/WX ${{ matrix.configuration.cpp_flags }}" cmake -B build -DSECP256K1_ENABLE_MODULE_RECOVERY=ON -DSECP256K1_BUILD_EXAMPLES=ON ${{ matrix.configuration.cmake_options }}
+
+      - name: Build
+        run: cmake --build build --config RelWithDebInfo -- /p:UseMultiToolTask=true /maxCpuCount
+
+      - name: Binaries info
+        # Use the bash shell included with Git for Windows.
+        shell: bash
+        run: |
+          cd build/src/RelWithDebInfo && file *tests.exe bench*.exe libsecp256k1-*.dll || true
+
+      - name: Check
+        run: |
+          ctest -C RelWithDebInfo --test-dir build -j ([int]$env:NUMBER_OF_PROCESSORS + 1)
+          build\src\RelWithDebInfo\bench_ecmult.exe
+          build\src\RelWithDebInfo\bench_internal.exe
+          build\src\RelWithDebInfo\bench.exe
+
+  win64-native-headers:
+    name: "x64 (MSVC): C++ (public headers)"
+    # See: https://github.com/actions/runner-images#available-images.
+    runs-on: windows-2022
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Add cl.exe to PATH
+        uses: ilammy/msvc-dev-cmd@v1
+
+      - name: C++ (public headers)
+        run: |
+          cl.exe -c -WX -TP include/*.h
+
+  cxx_fpermissive_debian:
+    name: "C++ -fpermissive (entire project)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    env:
+      CC: 'g++'
+      CFLAGS: '-fpermissive -g'
+      CPPFLAGS: '-DSECP256K1_CPLUSPLUS_TEST_OVERRIDE'
+      WERROR_CFLAGS:
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
+  cxx_headers_debian:
+    name: "C++ (public headers)"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+          command: |
+            g++ -Werror include/*.h
+            clang -Werror -x c++-header include/*.h
+
+  sage:
+    name: "SageMath prover"
+    runs-on: ubuntu-latest
+    container:
+      image: sagemath/sagemath:latest
+      options: --user root
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: CI script
+        run: |
+          cd sage
+          sage prove_group_implementations.sage
+
+  release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - run: ./autogen.sh && ./configure --enable-dev-mode && make distcheck
+
+      - name: Check installation with Autotools
+        env:
+          CI_INSTALL: ${{ runner.temp }}/${{ github.run_id }}${{ github.action }}/install
+        run: |
+          ./autogen.sh && ./configure --prefix=${{ env.CI_INSTALL }} && make clean && make install && ls -RlAh ${{ env.CI_INSTALL }}
+          gcc -o ecdsa examples/ecdsa.c $(PKG_CONFIG_PATH=${{ env.CI_INSTALL }}/lib/pkgconfig pkg-config --cflags --libs libsecp256k1) -Wl,-rpath,"${{ env.CI_INSTALL }}/lib" && ./ecdsa
+
+      - name: Check installation with CMake
+        env:
+          CI_BUILD: ${{ runner.temp }}/${{ github.run_id }}${{ github.action }}/build
+          CI_INSTALL: ${{ runner.temp }}/${{ github.run_id }}${{ github.action }}/install
+        run: |
+          cmake -B ${{ env.CI_BUILD }} -DCMAKE_INSTALL_PREFIX=${{ env.CI_INSTALL }} && cmake --build ${{ env.CI_BUILD }} --target install && ls -RlAh ${{ env.CI_INSTALL }}
+          gcc -o ecdsa examples/ecdsa.c -I ${{ env.CI_INSTALL }}/include -L ${{ env.CI_INSTALL }}/lib*/ -l secp256k1 -Wl,-rpath,"${{ env.CI_INSTALL }}/lib",-rpath,"${{ env.CI_INSTALL }}/lib64" && ./ecdsa

.gitignore

@@ -1,11 +1,12 @@
 bench
 bench_ecmult
 bench_internal
+noverify_tests
 tests
 exhaustive_tests
 precompute_ecmult_gen
 precompute_ecmult
-valgrind_ctime_test
+ctime_tests
 ecdh_example
 ecdsa_example
 schnorr_example
@@ -42,8 +43,6 @@ coverage.*.html
 *.gcno
 *.gcov
 
-src/libsecp256k1-config.h
-src/libsecp256k1-config.h.in
 build-aux/ar-lib
 build-aux/config.guess
 build-aux/config.sub
@@ -58,5 +57,9 @@ build-aux/m4/ltversion.m4
 build-aux/missing
 build-aux/compile
 build-aux/test-driver
-src/stamp-h1
 libsecp256k1.pc
+
+### CMake
+/CMakeUserPresets.json
+# Default CMake build directory.
+/build

CHANGELOG.md

@@ -1,28 +1,122 @@
 # Changelog
 
-The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+All notable changes to this project will be documented in this file.
 
-## [Unreleased]
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.4.1] - 2023-12-21
+
+#### Changed
+ - The point multiplication algorithm used for ECDH operations (module `ecdh`) was replaced with a slightly faster one.
+ - Optional handwritten x86_64 assembly for field operations was removed because modern C compilers are able to output more efficient assembly. This change results in a significant speedup of some library functions when handwritten x86_64 assembly is enabled (`--with-asm=x86_64` in GNU Autotools, `-DSECP256K1_ASM=x86_64` in CMake), which is the default on x86_64. Benchmarks with GCC 10.5.0 show a 10% speedup for `secp256k1_ecdsa_verify` and `secp256k1_schnorrsig_verify`.
+
+#### ABI Compatibility
+The ABI is backward compatible with versions 0.4.0 and 0.3.x.
+
+## [0.4.0] - 2023-09-04
+
+#### Added
+ - New module `ellswift` implements ElligatorSwift encoding for public keys and x-only Diffie-Hellman key exchange for them.
+   ElligatorSwift permits representing secp256k1 public keys as 64-byte arrays which cannot be distinguished from uniformly random. See:
+   - Header file `include/secp256k1_ellswift.h` which defines the new API.
+   - Document `doc/ellswift.md` which explains the mathematical background of the scheme.
+   - The [paper](https://eprint.iacr.org/2022/759) on which the scheme is based.
+ - We now test the library with unreleased development snapshots of GCC and Clang. This gives us an early chance to catch miscompilations and constant-time issues introduced by the compiler (such as those that led to the previous two releases).
+
+#### Fixed
+ - Fixed symbol visibility in Windows DLL builds, where three internal library symbols were wrongly exported.
+
+#### Changed
+ - When consuming libsecp256k1 as a static library on Windows, the user must now define the `SECP256K1_STATIC` macro before including `secp256k1.h`.
+
+#### ABI Compatibility
+This release is backward compatible with the ABI of 0.3.0, 0.3.1, and 0.3.2. Symbol visibility is now believed to be handled properly on supported platforms and is now considered to be part of the ABI. Please report any improperly exported symbols as a bug.
+
+## [0.3.2] - 2023-05-13
+We strongly recommend updating to 0.3.2 if you use or plan to use GCC >=13 to compile libsecp256k1. When in doubt, check the GCC version using `gcc -v`.
+
+#### Security
+ - Module `ecdh`: Fix "constant-timeness" issue with GCC 13.1 (and potentially future versions of GCC) that could leave applications using libsecp256k1's ECDH module vulnerable to a timing side-channel attack. The fix avoids secret-dependent control flow during ECDH computations when libsecp256k1 is compiled with GCC 13.1.
+
+#### Fixed
+ - Fixed an old bug that permitted compilers to potentially output bad assembly code on x86_64. In theory, it could lead to a crash or a read of unrelated memory, but this has never been observed on any compilers so far.
+
+#### Changed
+ - Various improvements and changes to CMake builds. CMake builds remain experimental.
+   - Made API versioning consistent with GNU Autotools builds.
+   - Switched to `BUILD_SHARED_LIBS` variable for controlling whether to build a static or a shared library.
+   - Added `SECP256K1_INSTALL` variable for the controlling whether to install the build artefacts.
+ - Renamed asm build option `arm` to `arm32`. Use `--with-asm=arm32` instead of `--with-asm=arm` (GNU Autotools), and `-DSECP256K1_ASM=arm32` instead of `-DSECP256K1_ASM=arm` (CMake).
+
+#### ABI Compatibility
+The ABI is compatible with versions 0.3.0 and 0.3.1.
+
+## [0.3.1] - 2023-04-10
+We strongly recommend updating to 0.3.1 if you use or plan to use Clang >=14 to compile libsecp256k1, e.g., Xcode >=14 on macOS has Clang >=14. When in doubt, check the Clang version using `clang -v`.
+
+#### Security
+ - Fix "constant-timeness" issue with Clang >=14 that could leave applications using libsecp256k1 vulnerable to a timing side-channel attack. The fix avoids secret-dependent control flow and secret-dependent memory accesses in conditional moves of memory objects when libsecp256k1 is compiled with Clang >=14.
+
+#### Added
+  - Added tests against [Project Wycheproof's](https://github.com/google/wycheproof/) set of ECDSA test vectors (Bitcoin "low-S" variant), a fixed set of test cases designed to trigger various edge cases.
+
+#### Changed
+ - Increased minimum required CMake version to 3.13. CMake builds remain experimental.
+
+#### ABI Compatibility
+The ABI is compatible with version 0.3.0.
+
+## [0.3.0] - 2023-03-08
+
+#### Added
+ - Added experimental support for CMake builds. Traditional GNU Autotools builds (`./configure` and `make`) remain fully supported.
+ - Usage examples: Added a recommended method for securely clearing sensitive data, e.g., secret keys, from memory.
+ - Tests: Added a new test binary `noverify_tests`. This binary runs the tests without some additional checks present in the ordinary `tests` binary and is thereby closer to production binaries. The `noverify_tests` binary is automatically run as part of the `make check` target.
+
+#### Fixed
+ - Fixed declarations of API variables for MSVC (`__declspec(dllimport)`). This fixes MSVC builds of programs which link against a libsecp256k1 DLL dynamically and use API variables (and not only API functions). Unfortunately, the MSVC linker now will emit warning `LNK4217` when trying to link against libsecp256k1 statically. Pass `/ignore:4217` to the linker to suppress this warning.
+
+#### Changed
+ - Forbade cloning or destroying `secp256k1_context_static`. Create a new context instead of cloning the static context. (If this change breaks your code, your code is probably wrong.)
+ - Forbade randomizing (copies of) `secp256k1_context_static`. Randomizing a copy of `secp256k1_context_static` did not have any effect and did not provide defense-in-depth protection against side-channel attacks. Create a new context if you want to benefit from randomization.
+
+#### Removed
+ - Removed the configuration header `src/libsecp256k1-config.h`. We recommend passing flags to `./configure` or `cmake` to set configuration options (see `./configure --help` or `cmake -LH`). If you cannot or do not want to use one of the supported build systems, pass configuration flags such as `-DSECP256K1_ENABLE_MODULE_SCHNORRSIG` manually to the compiler (see the file `configure.ac` for supported flags).
+
+#### ABI Compatibility
+Due to changes in the API regarding `secp256k1_context_static` described above, the ABI is *not* compatible with previous versions.
 
 ## [0.2.0] - 2022-12-12
 
-### Added
+#### Added
+ - Added usage examples for common use cases in a new `examples/` directory.
  - Added `secp256k1_selftest`, to be used in conjunction with `secp256k1_context_static`.
+ - Added support for 128-bit wide multiplication on MSVC for x86_64 and arm64, giving roughly a 20% speedup on those platforms.
 
-### Changed
- - Enabled modules schnorrsig, extrakeys and ECDH by default in `./configure`.
+#### Changed
+ - Enabled modules `schnorrsig`, `extrakeys` and `ecdh` by default in `./configure`.
+ - The `secp256k1_nonce_function_rfc6979` nonce function, used by default by `secp256k1_ecdsa_sign`, now reduces the message hash modulo the group order to match the specification. This only affects improper use of ECDSA signing API.
 
-### Deprecated
+#### Deprecated
  - Deprecated context flags `SECP256K1_CONTEXT_VERIFY` and `SECP256K1_CONTEXT_SIGN`. Use `SECP256K1_CONTEXT_NONE` instead.
  - Renamed `secp256k1_context_no_precomp` to `secp256k1_context_static`.
+ - Module `schnorrsig`: renamed `secp256k1_schnorrsig_sign` to `secp256k1_schnorrsig_sign32`.
 
-### ABI Compatibility
-
+#### ABI Compatibility
 Since this is the first release, we do not compare application binary interfaces.
-However, there are unreleased versions of libsecp256k1 that are *not* ABI compatible with this version.
+However, there are earlier unreleased versions of libsecp256k1 that are *not* ABI compatible with this version.
 
 ## [0.1.0] - 2013-03-05 to 2021-12-25
 
 This version was in fact never released.
 The number was given by the build system since the introduction of autotools in Jan 2014 (ea0fe5a5bf0c04f9cc955b2966b614f5f378c6f6).
 Therefore, this version number does not uniquely identify a set of source files.
+
+[0.4.1]: https://github.com/bitcoin-core/secp256k1/compare/v0.4.0...v0.4.1
+[0.4.0]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.2...v0.4.0
+[0.3.2]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.1...v0.3.2
+[0.3.1]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.0...v0.3.1
+[0.3.0]: https://github.com/bitcoin-core/secp256k1/compare/v0.2.0...v0.3.0
+[0.2.0]: https://github.com/bitcoin-core/secp256k1/compare/423b6d19d373f1224fd671a982584d7e7900bc93..v0.2.0
+[0.1.0]: https://github.com/bitcoin-core/secp256k1/commit/423b6d19d373f1224fd671a982584d7e7900bc93

CMakeLists.txt

@@ -0,0 +1,341 @@
+cmake_minimum_required(VERSION 3.13)
+
+if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.15)
+  # MSVC runtime library flags are selected by the CMAKE_MSVC_RUNTIME_LIBRARY abstraction.
+  cmake_policy(SET CMP0091 NEW)
+  # MSVC warning flags are not in CMAKE_<LANG>_FLAGS by default.
+  cmake_policy(SET CMP0092 NEW)
+endif()
+
+project(libsecp256k1
+  # The package (a.k.a. release) version is based on semantic versioning 2.0.0 of
+  # the API. All changes in experimental modules are treated as
+  # backwards-compatible and therefore at most increase the minor version.
+  VERSION 0.4.1
+  DESCRIPTION "Optimized C library for ECDSA signatures and secret/public key operations on curve secp256k1."
+  HOMEPAGE_URL "https://github.com/bitcoin-core/secp256k1"
+  LANGUAGES C
+)
+
+if(CMAKE_VERSION VERSION_LESS 3.21)
+  get_directory_property(parent_directory PARENT_DIRECTORY)
+  if(parent_directory)
+    set(PROJECT_IS_TOP_LEVEL OFF CACHE INTERNAL "Emulates CMake 3.21+ behavior.")
+    set(${PROJECT_NAME}_IS_TOP_LEVEL OFF CACHE INTERNAL "Emulates CMake 3.21+ behavior.")
+  else()
+    set(PROJECT_IS_TOP_LEVEL ON CACHE INTERNAL "Emulates CMake 3.21+ behavior.")
+    set(${PROJECT_NAME}_IS_TOP_LEVEL ON CACHE INTERNAL "Emulates CMake 3.21+ behavior.")
+  endif()
+  unset(parent_directory)
+endif()
+
+# The library version is based on libtool versioning of the ABI. The set of
+# rules for updating the version can be found here:
+# https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
+# All changes in experimental modules are treated as if they don't affect the
+# interface and therefore only increase the revision.
+set(${PROJECT_NAME}_LIB_VERSION_CURRENT 3)
+set(${PROJECT_NAME}_LIB_VERSION_REVISION 1)
+set(${PROJECT_NAME}_LIB_VERSION_AGE 1)
+
+set(CMAKE_C_STANDARD 90)
+set(CMAKE_C_EXTENSIONS OFF)
+
+list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
+
+option(BUILD_SHARED_LIBS "Build shared libraries." ON)
+option(SECP256K1_DISABLE_SHARED "Disable shared library. Overrides BUILD_SHARED_LIBS." OFF)
+if(SECP256K1_DISABLE_SHARED)
+  set(BUILD_SHARED_LIBS OFF)
+endif()
+
+option(SECP256K1_INSTALL "Enable installation." ${PROJECT_IS_TOP_LEVEL})
+
+option(SECP256K1_ENABLE_MODULE_ECDH "Enable ECDH module." ON)
+if(SECP256K1_ENABLE_MODULE_ECDH)
+  add_compile_definitions(ENABLE_MODULE_ECDH=1)
+endif()
+
+option(SECP256K1_ENABLE_MODULE_RECOVERY "Enable ECDSA pubkey recovery module." OFF)
+if(SECP256K1_ENABLE_MODULE_RECOVERY)
+  add_compile_definitions(ENABLE_MODULE_RECOVERY=1)
+endif()
+
+option(SECP256K1_ENABLE_MODULE_EXTRAKEYS "Enable extrakeys module." ON)
+option(SECP256K1_ENABLE_MODULE_SCHNORRSIG "Enable schnorrsig module." ON)
+if(SECP256K1_ENABLE_MODULE_SCHNORRSIG)
+  set(SECP256K1_ENABLE_MODULE_EXTRAKEYS ON)
+  add_compile_definitions(ENABLE_MODULE_SCHNORRSIG=1)
+endif()
+if(SECP256K1_ENABLE_MODULE_EXTRAKEYS)
+  add_compile_definitions(ENABLE_MODULE_EXTRAKEYS=1)
+endif()
+
+option(SECP256K1_ENABLE_MODULE_ELLSWIFT "Enable ElligatorSwift module." ON)
+if(SECP256K1_ENABLE_MODULE_ELLSWIFT)
+  add_compile_definitions(ENABLE_MODULE_ELLSWIFT=1)
+endif()
+
+option(SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS "Enable external default callback functions." OFF)
+if(SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS)
+  add_compile_definitions(USE_EXTERNAL_DEFAULT_CALLBACKS=1)
+endif()
+
+set(SECP256K1_ECMULT_WINDOW_SIZE "AUTO" CACHE STRING "Window size for ecmult precomputation for verification, specified as integer in range [2..24]. \"AUTO\" is a reasonable setting for desktop machines (currently 15). [default=AUTO]")
+set_property(CACHE SECP256K1_ECMULT_WINDOW_SIZE PROPERTY STRINGS "AUTO" 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24)
+include(CheckStringOptionValue)
+check_string_option_value(SECP256K1_ECMULT_WINDOW_SIZE)
+if(SECP256K1_ECMULT_WINDOW_SIZE STREQUAL "AUTO")
+  set(SECP256K1_ECMULT_WINDOW_SIZE 15)
+endif()
+add_compile_definitions(ECMULT_WINDOW_SIZE=${SECP256K1_ECMULT_WINDOW_SIZE})
+
+set(SECP256K1_ECMULT_GEN_PREC_BITS "AUTO" CACHE STRING "Precision bits to tune the precomputed table size for signing, specified as integer 2, 4 or 8. \"AUTO\" is a reasonable setting for desktop machines (currently 4). [default=AUTO]")
+set_property(CACHE SECP256K1_ECMULT_GEN_PREC_BITS PROPERTY STRINGS "AUTO" 2 4 8)
+check_string_option_value(SECP256K1_ECMULT_GEN_PREC_BITS)
+if(SECP256K1_ECMULT_GEN_PREC_BITS STREQUAL "AUTO")
+  set(SECP256K1_ECMULT_GEN_PREC_BITS 4)
+endif()
+add_compile_definitions(ECMULT_GEN_PREC_BITS=${SECP256K1_ECMULT_GEN_PREC_BITS})
+
+set(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY "OFF" CACHE STRING "Test-only override of the (autodetected by the C code) \"widemul\" setting. Legal values are: \"OFF\", \"int128_struct\", \"int128\" or \"int64\". [default=OFF]")
+set_property(CACHE SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY PROPERTY STRINGS "OFF" "int128_struct" "int128" "int64")
+check_string_option_value(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
+if(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
+  string(TOUPPER "${SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY}" widemul_upper_value)
+  add_compile_definitions(USE_FORCE_WIDEMUL_${widemul_upper_value}=1)
+endif()
+mark_as_advanced(FORCE SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
+
+set(SECP256K1_ASM "AUTO" CACHE STRING "Assembly to use: \"AUTO\", \"OFF\", \"x86_64\" or \"arm32\" (experimental). [default=AUTO]")
+set_property(CACHE SECP256K1_ASM PROPERTY STRINGS "AUTO" "OFF" "x86_64" "arm32")
+check_string_option_value(SECP256K1_ASM)
+if(SECP256K1_ASM STREQUAL "arm32")
+  enable_language(ASM)
+  include(CheckArm32Assembly)
+  check_arm32_assembly()
+  if(HAVE_ARM32_ASM)
+    add_compile_definitions(USE_EXTERNAL_ASM=1)
+  else()
+    message(FATAL_ERROR "ARM32 assembly requested but not available.")
+  endif()
+elseif(SECP256K1_ASM)
+  include(CheckX86_64Assembly)
+  check_x86_64_assembly()
+  if(HAVE_X86_64_ASM)
+    set(SECP256K1_ASM "x86_64")
+    add_compile_definitions(USE_ASM_X86_64=1)
+  elseif(SECP256K1_ASM STREQUAL "AUTO")
+    set(SECP256K1_ASM "OFF")
+  else()
+    message(FATAL_ERROR "x86_64 assembly requested but not available.")
+  endif()
+endif()
+
+option(SECP256K1_EXPERIMENTAL "Allow experimental configuration options." OFF)
+if(NOT SECP256K1_EXPERIMENTAL)
+  if(SECP256K1_ASM STREQUAL "arm32")
+    message(FATAL_ERROR "ARM32 assembly is experimental. Use -DSECP256K1_EXPERIMENTAL=ON to allow.")
+  endif()
+endif()
+
+set(SECP256K1_VALGRIND "AUTO" CACHE STRING "Build with extra checks for running inside Valgrind. [default=AUTO]")
+set_property(CACHE SECP256K1_VALGRIND PROPERTY STRINGS "AUTO" "OFF" "ON")
+check_string_option_value(SECP256K1_VALGRIND)
+if(SECP256K1_VALGRIND)
+  find_package(Valgrind MODULE)
+  if(Valgrind_FOUND)
+    set(SECP256K1_VALGRIND ON)
+    include_directories(${Valgrind_INCLUDE_DIR})
+    add_compile_definitions(VALGRIND)
+  elseif(SECP256K1_VALGRIND STREQUAL "AUTO")
+    set(SECP256K1_VALGRIND OFF)
+  else()
+    message(FATAL_ERROR "Valgrind support requested but valgrind/memcheck.h header not available.")
+  endif()
+endif()
+
+option(SECP256K1_BUILD_BENCHMARK "Build benchmarks." ON)
+option(SECP256K1_BUILD_TESTS "Build tests." ON)
+option(SECP256K1_BUILD_EXHAUSTIVE_TESTS "Build exhaustive tests." ON)
+option(SECP256K1_BUILD_CTIME_TESTS "Build constant-time tests." ${SECP256K1_VALGRIND})
+option(SECP256K1_BUILD_EXAMPLES "Build examples." OFF)
+
+# Redefine configuration flags.
+# We leave assertions on, because they are only used in the examples, and we want them always on there.
+if(MSVC)
+  string(REGEX REPLACE "/DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO}")
+  string(REGEX REPLACE "/DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
+  string(REGEX REPLACE "/DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL}")
+else()
+  string(REGEX REPLACE "-DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO}")
+  string(REGEX REPLACE "-DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
+  string(REGEX REPLACE "-DNDEBUG[ \t\r\n]*" "" CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL}")
+  # Prefer -O2 optimization level. (-O3 is CMake's default for Release for many compilers.)
+  string(REGEX REPLACE "-O3[ \t\r\n]*" "-O2" CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
+endif()
+
+# Define custom "Coverage" build type.
+set(CMAKE_C_FLAGS_COVERAGE "${CMAKE_C_FLAGS_RELWITHDEBINFO} -O0 -DCOVERAGE=1 --coverage" CACHE STRING
+  "Flags used by the C compiler during \"Coverage\" builds."
+  FORCE
+)
+set(CMAKE_EXE_LINKER_FLAGS_COVERAGE "${CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO} --coverage" CACHE STRING
+  "Flags used for linking binaries during \"Coverage\" builds."
+  FORCE
+)
+set(CMAKE_SHARED_LINKER_FLAGS_COVERAGE "${CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO} --coverage" CACHE STRING
+  "Flags used by the shared libraries linker during \"Coverage\" builds."
+  FORCE
+)
+mark_as_advanced(
+  CMAKE_C_FLAGS_COVERAGE
+  CMAKE_EXE_LINKER_FLAGS_COVERAGE
+  CMAKE_SHARED_LINKER_FLAGS_COVERAGE
+)
+
+get_property(is_multi_config GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
+set(default_build_type "RelWithDebInfo")
+if(is_multi_config)
+  set(CMAKE_CONFIGURATION_TYPES "${default_build_type}" "Release" "Debug" "MinSizeRel" "Coverage" CACHE STRING
+    "Supported configuration types."
+    FORCE
+  )
+else()
+  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY
+    STRINGS "${default_build_type}" "Release" "Debug" "MinSizeRel" "Coverage"
+  )
+  if(NOT CMAKE_BUILD_TYPE)
+    message(STATUS "Setting build type to \"${default_build_type}\" as none was specified")
+    set(CMAKE_BUILD_TYPE "${default_build_type}" CACHE STRING
+      "Choose the type of build."
+      FORCE
+    )
+  endif()
+endif()
+
+include(TryAppendCFlags)
+if(MSVC)
+  # Keep the following commands ordered lexicographically.
+  try_append_c_flags(/W3) # Production quality warning level.
+  try_append_c_flags(/wd4146) # Disable warning C4146 "unary minus operator applied to unsigned type, result still unsigned".
+  try_append_c_flags(/wd4244) # Disable warning C4244 "'conversion' conversion from 'type1' to 'type2', possible loss of data".
+  try_append_c_flags(/wd4267) # Disable warning C4267 "'var' : conversion from 'size_t' to 'type', possible loss of data".
+  # Eliminate deprecation warnings for the older, less secure functions.
+  add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
+else()
+  # Keep the following commands ordered lexicographically.
+  try_append_c_flags(-pedantic)
+  try_append_c_flags(-Wall) # GCC >= 2.95 and probably many other compilers.
+  try_append_c_flags(-Wcast-align) # GCC >= 2.95.
+  try_append_c_flags(-Wcast-align=strict) # GCC >= 8.0.
+  try_append_c_flags(-Wconditional-uninitialized) # Clang >= 3.0 only.
+  try_append_c_flags(-Wextra) # GCC >= 3.4, this is the newer name of -W, which we don't use because older GCCs will warn about unused functions.
+  try_append_c_flags(-Wnested-externs)
+  try_append_c_flags(-Wno-long-long) # GCC >= 3.0, -Wlong-long is implied by -pedantic.
+  try_append_c_flags(-Wno-overlength-strings) # GCC >= 4.2, -Woverlength-strings is implied by -pedantic.
+  try_append_c_flags(-Wno-unused-function) # GCC >= 3.0, -Wunused-function is implied by -Wall.
+  try_append_c_flags(-Wreserved-identifier) # Clang >= 13.0 only.
+  try_append_c_flags(-Wshadow)
+  try_append_c_flags(-Wstrict-prototypes)
+  try_append_c_flags(-Wundef)
+endif()
+
+set(CMAKE_C_VISIBILITY_PRESET hidden)
+
+# Ask CTest to create a "check" target (e.g., make check) as alias for the "test" target.
+# CTEST_TEST_TARGET_ALIAS is not documented but supposed to be user-facing.
+# See: https://gitlab.kitware.com/cmake/cmake/-/commit/816c9d1aa1f2b42d40c81a991b68c96eb12b6d2
+set(CTEST_TEST_TARGET_ALIAS check)
+include(CTest)
+# We do not use CTest's BUILD_TESTING because a single toggle for all tests is too coarse for our needs.
+mark_as_advanced(BUILD_TESTING)
+if(SECP256K1_BUILD_BENCHMARK OR SECP256K1_BUILD_TESTS OR SECP256K1_BUILD_EXHAUSTIVE_TESTS OR SECP256K1_BUILD_CTIME_TESTS OR SECP256K1_BUILD_EXAMPLES)
+  enable_testing()
+endif()
+
+add_subdirectory(src)
+if(SECP256K1_BUILD_EXAMPLES)
+  add_subdirectory(examples)
+endif()
+
+message("\n")
+message("secp256k1 configure summary")
+message("===========================")
+message("Build artifacts:")
+if(BUILD_SHARED_LIBS)
+  set(library_type "Shared")
+else()
+  set(library_type "Static")
+endif()
+
+message("  library type ........................ ${library_type}")
+message("Optional modules:")
+message("  ECDH ................................ ${SECP256K1_ENABLE_MODULE_ECDH}")
+message("  ECDSA pubkey recovery ............... ${SECP256K1_ENABLE_MODULE_RECOVERY}")
+message("  extrakeys ........................... ${SECP256K1_ENABLE_MODULE_EXTRAKEYS}")
+message("  schnorrsig .......................... ${SECP256K1_ENABLE_MODULE_SCHNORRSIG}")
+message("  ElligatorSwift ...................... ${SECP256K1_ENABLE_MODULE_ELLSWIFT}")
+message("Parameters:")
+message("  ecmult window size .................. ${SECP256K1_ECMULT_WINDOW_SIZE}")
+message("  ecmult gen precision bits ........... ${SECP256K1_ECMULT_GEN_PREC_BITS}")
+message("Optional features:")
+message("  assembly ............................ ${SECP256K1_ASM}")
+message("  external callbacks .................. ${SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS}")
+if(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
+  message("  wide multiplication (test-only) ..... ${SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY}")
+endif()
+message("Optional binaries:")
+message("  benchmark ........................... ${SECP256K1_BUILD_BENCHMARK}")
+message("  noverify_tests ...................... ${SECP256K1_BUILD_TESTS}")
+set(tests_status "${SECP256K1_BUILD_TESTS}")
+if(CMAKE_BUILD_TYPE STREQUAL "Coverage")
+  set(tests_status OFF)
+endif()
+message("  tests ............................... ${tests_status}")
+message("  exhaustive tests .................... ${SECP256K1_BUILD_EXHAUSTIVE_TESTS}")
+message("  ctime_tests ......................... ${SECP256K1_BUILD_CTIME_TESTS}")
+message("  examples ............................ ${SECP256K1_BUILD_EXAMPLES}")
+message("")
+if(CMAKE_CROSSCOMPILING)
+  set(cross_status "TRUE, for ${CMAKE_SYSTEM_NAME}, ${CMAKE_SYSTEM_PROCESSOR}")
+else()
+  set(cross_status "FALSE")
+endif()
+message("Cross compiling ....................... ${cross_status}")
+message("Valgrind .............................. ${SECP256K1_VALGRIND}")
+get_directory_property(definitions COMPILE_DEFINITIONS)
+string(REPLACE ";" " " definitions "${definitions}")
+message("Preprocessor defined macros ........... ${definitions}")
+message("C compiler ............................ ${CMAKE_C_COMPILER}")
+message("CFLAGS ................................ ${CMAKE_C_FLAGS}")
+get_directory_property(compile_options COMPILE_OPTIONS)
+string(REPLACE ";" " " compile_options "${compile_options}")
+message("Compile options ....................... " ${compile_options})
+if(NOT is_multi_config)
+  message("Build type:")
+  message(" - CMAKE_BUILD_TYPE ................... ${CMAKE_BUILD_TYPE}")
+  string(TOUPPER "${CMAKE_BUILD_TYPE}" build_type)
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_${build_type}}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_${build_type}}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_${build_type}}")
+else()
+  message("Supported configurations .............. ${CMAKE_CONFIGURATION_TYPES}")
+  message("RelWithDebInfo configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_RELWITHDEBINFO}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO}")
+  message("Debug configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_DEBUG}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_DEBUG}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_DEBUG}")
+endif()
+message("\n")
+if(SECP256K1_EXPERIMENTAL)
+  message(
+    "  ******\n"
+    "  WARNING: experimental build\n"
+    "  Experimental features do not have stable APIs or properties, and may not be safe for production use.\n"
+    "  ******\n"
+  )
+endif()

CMakePresets.json

@@ -0,0 +1,19 @@
+{
+  "cmakeMinimumRequired": {"major": 3, "minor": 21, "patch": 0}, 
+  "version": 3,
+  "configurePresets": [
+    {
+      "name": "dev-mode",
+      "displayName": "Development mode (intended only for developers of the library)",
+      "cacheVariables": {
+        "SECP256K1_EXPERIMENTAL": "ON",
+        "SECP256K1_ENABLE_MODULE_RECOVERY": "ON",
+        "SECP256K1_BUILD_EXAMPLES": "ON"
+      },
+      "warnings": {
+        "dev": true,
+        "uninitialized": true
+      }
+    }
+  ]
+}

CONTRIBUTING.md

@@ -0,0 +1,107 @@
+# Contributing to libsecp256k1
+
+## Scope
+
+libsecp256k1 is a library for elliptic curve cryptography on the curve secp256k1, not a general-purpose cryptography library.
+The library primarily serves the needs of the Bitcoin Core project but provides additional functionality for the benefit of the wider Bitcoin ecosystem.
+
+## Adding new functionality or modules
+
+The libsecp256k1 project welcomes contributions in the form of new functionality or modules, provided they are within the project's scope.
+
+It is the responsibility of the contributors to convince the maintainers that the proposed functionality is within the project's scope, high-quality and maintainable.
+Contributors are recommended to provide the following in addition to the new code:
+
+* **Specification:**
+    A specification can help significantly in reviewing the new code as it provides documentation and context.
+    It may justify various design decisions, give a motivation and outline security goals.
+    If the specification contains pseudocode, a reference implementation or test vectors, these can be used to compare with the proposed libsecp256k1 code.
+* **Security Arguments:**
+    In addition to a defining the security goals, it should be argued that the new functionality meets these goals.
+    Depending on the nature of the new functionality, a wide range of security arguments are acceptable, ranging from being "obviously secure" to rigorous proofs of security.
+* **Relevance Arguments:**
+    The relevance of the new functionality for the Bitcoin ecosystem should be argued by outlining clear use cases.
+
+These are not the only factors taken into account when considering to add new functionality.
+The proposed new libsecp256k1 code must be of high quality, including API documentation and tests, as well as featuring a misuse-resistant API design.
+
+We recommend reaching out to other contributors (see [Communication Channels](#communication-channels)) and get feedback before implementing new functionality.
+
+## Communication channels
+
+Most communication about libsecp256k1 occurs on the GitHub repository: in issues, pull request or on the discussion board.
+
+Additionally, there is an IRC channel dedicated to libsecp256k1, with biweekly meetings (see channel topic).
+The channel is `#secp256k1` on Libera Chat.
+The easiest way to participate on IRC is with the web client, [web.libera.chat](https://web.libera.chat/#secp256k1).
+Chat history logs can be found at https://gnusha.org/secp256k1/.
+
+## Contributor workflow & peer review
+
+The Contributor Workflow & Peer Review in libsecp256k1 are similar to Bitcoin Core's workflow and review processes described in its [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md).
+
+### Coding conventions
+
+In addition, libsecp256k1 tries to maintain the following coding conventions:
+
+* No runtime heap allocation (e.g., no `malloc`) unless explicitly requested by the caller (via `secp256k1_context_create` or `secp256k1_scratch_space_create`, for example). Morever, it should be possible to use the library without any heap allocations.
+* The tests should cover all lines and branches of the library (see [Test coverage](#coverage)).
+* Operations involving secret data should be tested for being constant time with respect to the secrets (see [src/ctime_tests.c](src/ctime_tests.c)).
+* Local variables containing secret data should be cleared explicitly to try to delete secrets from memory.
+* Use `secp256k1_memcmp_var` instead of `memcmp` (see [#823](https://github.com/bitcoin-core/secp256k1/issues/823)).
+
+#### Style conventions
+
+* Commits should be atomic and diffs should be easy to read. For this reason, do not mix any formatting fixes or code moves with actual code changes. Make sure each individual commit is hygienic: that it builds successfully on its own without warnings, errors, regressions, or test failures.
+* New code should adhere to the style of existing, in particular surrounding, code. Other than that, we do not enforce strict rules for code formatting.
+* The code conforms to C89. Most notably, that means that only `/* ... */` comments are allowed (no `//` line comments). Moreover, any declarations in a `{ ... }` block (e.g., a function) must appear at the beginning of the block before any statements. When you would like to declare a variable in the middle of a block, you can open a new block:
+    ```C
+    void secp256k_foo(void) {
+        unsigned int x;              /* declaration */
+        int y = 2*x;                 /* declaration */
+        x = 17;                      /* statement */
+        {
+            int a, b;                /* declaration */
+            a = x + y;               /* statement */
+            secp256k_bar(x, &b);     /* statement */
+        }
+    }
+    ```
+* Use `unsigned int` instead of just `unsigned`.
+* Use `void *ptr` instead of `void* ptr`.
+* Arguments of the publicly-facing API must have a specific order defined in [include/secp256k1.h](include/secp256k1.h).
+* User-facing comment lines in headers should be limited to 80 chars if possible.
+* All identifiers in file scope should start with `secp256k1_`.
+* Avoid trailing whitespace.
+
+### Tests
+
+#### Coverage
+
+This library aims to have full coverage of reachable lines and branches.
+
+To create a test coverage report, configure with `--enable-coverage` (use of GCC is necessary):
+
+    $ ./configure --enable-coverage
+
+Run the tests:
+
+    $ make check
+
+To create a report, `gcovr` is recommended, as it includes branch coverage reporting:
+
+    $ gcovr --exclude 'src/bench*' --print-summary
+
+To create a HTML report with coloured and annotated source code:
+
+    $ mkdir -p coverage
+    $ gcovr --exclude 'src/bench*' --html --html-details -o coverage/coverage.html
+
+#### Exhaustive tests
+
+There are tests of several functions in which a small group replaces secp256k1.
+These tests are *exhaustive* since they provide all elements and scalars of the small group as input arguments (see [src/tests_exhaustive.c](src/tests_exhaustive.c)).
+
+### Benchmarks
+
+See `src/bench*.c` for examples of benchmarks.

Makefile.am

@@ -1,5 +1,3 @@
-.PHONY: clean-precomp precomp
-
 ACLOCAL_AMFLAGS = -I build-aux/m4
 
 # AM_CFLAGS will be automatically prepended to CFLAGS by Automake when compiling some foo
@@ -39,7 +37,6 @@ noinst_HEADERS += src/field_10x26_impl.h
 noinst_HEADERS += src/field_5x52.h
 noinst_HEADERS += src/field_5x52_impl.h
 noinst_HEADERS += src/field_5x52_int128_impl.h
-noinst_HEADERS += src/field_5x52_asm_impl.h
 noinst_HEADERS += src/modinv32.h
 noinst_HEADERS += src/modinv32_impl.h
 noinst_HEADERS += src/modinv64.h
@@ -47,6 +44,8 @@ noinst_HEADERS += src/modinv64_impl.h
 noinst_HEADERS += src/precomputed_ecmult.h
 noinst_HEADERS += src/precomputed_ecmult_gen.h
 noinst_HEADERS += src/assumptions.h
+noinst_HEADERS += src/checkmem.h
+noinst_HEADERS += src/testutil.h
 noinst_HEADERS += src/util.h
 noinst_HEADERS += src/int128.h
 noinst_HEADERS += src/int128_impl.h
@@ -64,16 +63,19 @@ noinst_HEADERS += src/hash_impl.h
 noinst_HEADERS += src/field.h
 noinst_HEADERS += src/field_impl.h
 noinst_HEADERS += src/bench.h
+noinst_HEADERS += src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.h
 noinst_HEADERS += contrib/lax_der_parsing.h
 noinst_HEADERS += contrib/lax_der_parsing.c
 noinst_HEADERS += contrib/lax_der_privatekey_parsing.h
 noinst_HEADERS += contrib/lax_der_privatekey_parsing.c
-noinst_HEADERS += examples/random.h
+noinst_HEADERS += examples/examples_util.h
 
 PRECOMPUTED_LIB = libsecp256k1_precomputed.la
 noinst_LTLIBRARIES = $(PRECOMPUTED_LIB)
 libsecp256k1_precomputed_la_SOURCES =  src/precomputed_ecmult.c src/precomputed_ecmult_gen.c
-libsecp256k1_precomputed_la_CPPFLAGS = $(SECP_INCLUDES)
+# We need `-I$(top_srcdir)/src` in VPATH builds if libsecp256k1_precomputed_la_SOURCES have been recreated in the build tree.
+# This helps users and packagers who insist on recreating the precomputed files (e.g., Gentoo).
+libsecp256k1_precomputed_la_CPPFLAGS = -I$(top_srcdir)/src $(SECP_CONFIG_DEFINES)
 
 if USE_EXTERNAL_ASM
 COMMON_LIB = libsecp256k1_common.la
@@ -92,55 +94,58 @@ endif
 endif
 
 libsecp256k1_la_SOURCES = src/secp256k1.c
-libsecp256k1_la_CPPFLAGS = $(SECP_INCLUDES)
-libsecp256k1_la_LIBADD = $(SECP_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
+libsecp256k1_la_CPPFLAGS = $(SECP_CONFIG_DEFINES)
+libsecp256k1_la_LIBADD = $(COMMON_LIB) $(PRECOMPUTED_LIB)
 libsecp256k1_la_LDFLAGS = -no-undefined -version-info $(LIB_VERSION_CURRENT):$(LIB_VERSION_REVISION):$(LIB_VERSION_AGE)
 
-if VALGRIND_ENABLED
-libsecp256k1_la_CPPFLAGS += -DVALGRIND
-endif
-
 noinst_PROGRAMS =
 if USE_BENCHMARK
 noinst_PROGRAMS += bench bench_internal bench_ecmult
 bench_SOURCES = src/bench.c
-bench_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
+bench_LDADD = libsecp256k1.la
+bench_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 bench_internal_SOURCES = src/bench_internal.c
-bench_internal_LDADD = $(SECP_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
-bench_internal_CPPFLAGS = $(SECP_INCLUDES)
+bench_internal_LDADD = $(COMMON_LIB) $(PRECOMPUTED_LIB)
+bench_internal_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 bench_ecmult_SOURCES = src/bench_ecmult.c
-bench_ecmult_LDADD = $(SECP_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
-bench_ecmult_CPPFLAGS = $(SECP_INCLUDES)
+bench_ecmult_LDADD = $(COMMON_LIB) $(PRECOMPUTED_LIB)
+bench_ecmult_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 endif
 
 TESTS =
 if USE_TESTS
-noinst_PROGRAMS += tests
-tests_SOURCES = src/tests.c
-tests_CPPFLAGS = $(SECP_INCLUDES) $(SECP_TEST_INCLUDES)
-if VALGRIND_ENABLED
-tests_CPPFLAGS += -DVALGRIND
-noinst_PROGRAMS += valgrind_ctime_test
-valgrind_ctime_test_SOURCES = src/valgrind_ctime_test.c
-valgrind_ctime_test_LDADD = libsecp256k1.la $(SECP_LIBS) $(COMMON_LIB)
-endif
+TESTS += noverify_tests
+noinst_PROGRAMS += noverify_tests
+noverify_tests_SOURCES = src/tests.c
+noverify_tests_CPPFLAGS = $(SECP_CONFIG_DEFINES)
+noverify_tests_LDADD = $(COMMON_LIB) $(PRECOMPUTED_LIB)
+noverify_tests_LDFLAGS = -static
 if !ENABLE_COVERAGE
-tests_CPPFLAGS += -DVERIFY
-endif
-tests_LDADD = $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
-tests_LDFLAGS = -static
 TESTS += tests
+noinst_PROGRAMS += tests
+tests_SOURCES  = $(noverify_tests_SOURCES)
+tests_CPPFLAGS = $(noverify_tests_CPPFLAGS) -DVERIFY
+tests_LDADD    = $(noverify_tests_LDADD)
+tests_LDFLAGS  = $(noverify_tests_LDFLAGS)
+endif
+endif
+
+if USE_CTIME_TESTS
+noinst_PROGRAMS += ctime_tests
+ctime_tests_SOURCES = src/ctime_tests.c
+ctime_tests_LDADD = libsecp256k1.la
+ctime_tests_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 endif
 
 if USE_EXHAUSTIVE_TESTS
 noinst_PROGRAMS += exhaustive_tests
 exhaustive_tests_SOURCES = src/tests_exhaustive.c
-exhaustive_tests_CPPFLAGS = $(SECP_INCLUDES)
+exhaustive_tests_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 if !ENABLE_COVERAGE
 exhaustive_tests_CPPFLAGS += -DVERIFY
 endif
 # Note: do not include $(PRECOMPUTED_LIB) in exhaustive_tests (it uses runtime-generated tables).
-exhaustive_tests_LDADD = $(SECP_LIBS) $(COMMON_LIB)
+exhaustive_tests_LDADD = $(COMMON_LIB)
 exhaustive_tests_LDFLAGS = -static
 TESTS += exhaustive_tests
 endif
@@ -148,7 +153,7 @@ endif
 if USE_EXAMPLES
 noinst_PROGRAMS += ecdsa_example
 ecdsa_example_SOURCES = examples/ecdsa.c
-ecdsa_example_CPPFLAGS = -I$(top_srcdir)/include
+ecdsa_example_CPPFLAGS = -I$(top_srcdir)/include -DSECP256K1_STATIC
 ecdsa_example_LDADD = libsecp256k1.la
 ecdsa_example_LDFLAGS = -static
 if BUILD_WINDOWS
@@ -158,7 +163,7 @@ TESTS += ecdsa_example
 if ENABLE_MODULE_ECDH
 noinst_PROGRAMS += ecdh_example
 ecdh_example_SOURCES = examples/ecdh.c
-ecdh_example_CPPFLAGS = -I$(top_srcdir)/include
+ecdh_example_CPPFLAGS = -I$(top_srcdir)/include -DSECP256K1_STATIC
 ecdh_example_LDADD = libsecp256k1.la
 ecdh_example_LDFLAGS = -static
 if BUILD_WINDOWS
@@ -169,7 +174,7 @@ endif
 if ENABLE_MODULE_SCHNORRSIG
 noinst_PROGRAMS += schnorr_example
 schnorr_example_SOURCES = examples/schnorr.c
-schnorr_example_CPPFLAGS = -I$(top_srcdir)/include
+schnorr_example_CPPFLAGS = -I$(top_srcdir)/include -DSECP256K1_STATIC
 schnorr_example_LDADD = libsecp256k1.la
 schnorr_example_LDFLAGS = -static
 if BUILD_WINDOWS
@@ -184,19 +189,19 @@ EXTRA_PROGRAMS = precompute_ecmult precompute_ecmult_gen
 CLEANFILES = $(EXTRA_PROGRAMS)
 
 precompute_ecmult_SOURCES = src/precompute_ecmult.c
-precompute_ecmult_CPPFLAGS = $(SECP_INCLUDES)
-precompute_ecmult_LDADD = $(SECP_LIBS) $(COMMON_LIB)
+precompute_ecmult_CPPFLAGS = $(SECP_CONFIG_DEFINES) -DVERIFY
+precompute_ecmult_LDADD = $(COMMON_LIB)
 
 precompute_ecmult_gen_SOURCES = src/precompute_ecmult_gen.c
-precompute_ecmult_gen_CPPFLAGS = $(SECP_INCLUDES)
-precompute_ecmult_gen_LDADD = $(SECP_LIBS) $(COMMON_LIB)
+precompute_ecmult_gen_CPPFLAGS = $(SECP_CONFIG_DEFINES) -DVERIFY
+precompute_ecmult_gen_LDADD = $(COMMON_LIB)
 
 # See Automake manual, Section "Errors with distclean".
 # We don't list any dependencies for the prebuilt files here because
 # otherwise make's decision whether to rebuild them (even in the first
 # build by a normal user) depends on mtimes, and thus is very fragile.
 # This means that rebuilds of the prebuilt files always need to be
-# forced by deleting them, e.g., by invoking `make clean-precomp`.
+# forced by deleting them.
 src/precomputed_ecmult.c:
 	$(MAKE) $(AM_MAKEFLAGS) precompute_ecmult$(EXEEXT)
 	./precompute_ecmult$(EXEEXT)
@@ -211,11 +216,29 @@ precomp: $(PRECOMP)
 # e.g., after `make maintainer-clean`).
 BUILT_SOURCES = $(PRECOMP)
 
-maintainer-clean-local: clean-precomp
-
+.PHONY: clean-precomp
 clean-precomp:
 	rm -f $(PRECOMP)
+maintainer-clean-local: clean-precomp
 
+### Pregenerated test vectors
+### (see the comments in the previous section for detailed rationale)
+TESTVECTORS = src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.h
+
+src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.h:
+	mkdir -p $(@D)
+	python3 $(top_srcdir)/tools/tests_wycheproof_generate.py $(top_srcdir)/src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.json > $@
+
+testvectors: $(TESTVECTORS)
+
+BUILT_SOURCES += $(TESTVECTORS)
+
+.PHONY: clean-testvectors
+clean-testvectors:
+	rm -f $(TESTVECTORS)
+maintainer-clean-local: clean-testvectors
+
+### Additional files to distribute
 EXTRA_DIST = autogen.sh CHANGELOG.md SECURITY.md
 EXTRA_DIST += doc/release-process.md doc/safegcd_implementation.md
 EXTRA_DIST += examples/EXAMPLES_COPYING
@@ -225,6 +248,9 @@ EXTRA_DIST += sage/group_prover.sage
 EXTRA_DIST += sage/prove_group_implementations.sage
 EXTRA_DIST += sage/secp256k1_params.sage
 EXTRA_DIST += sage/weierstrass_prover.sage
+EXTRA_DIST += src/wycheproof/WYCHEPROOF_COPYING
+EXTRA_DIST += src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.json
+EXTRA_DIST += tools/tests_wycheproof_generate.py
 
 if ENABLE_MODULE_ECDH
 include src/modules/ecdh/Makefile.am.include
@@ -241,3 +267,7 @@ endif
 if ENABLE_MODULE_SCHNORRSIG
 include src/modules/schnorrsig/Makefile.am.include
 endif
+
+if ENABLE_MODULE_ELLSWIFT
+include src/modules/ellswift/Makefile.am.include
+endif

README.md

@@ -1,11 +1,10 @@
 libsecp256k1
 ============
 
-[![Build Status](https://api.cirrus-ci.com/github/bitcoin-core/secp256k1.svg?branch=master)](https://cirrus-ci.com/github/bitcoin-core/secp256k1)
 ![Dependencies: None](https://img.shields.io/badge/dependencies-none-success)
 [![irc.libera.chat #secp256k1](https://img.shields.io/badge/irc.libera.chat-%23secp256k1-success)](https://web.libera.chat/#secp256k1)
 
-Optimized C library for ECDSA signatures and secret/public key operations on curve secp256k1.
+High-performance high-assurance C library for digital signatures and other cryptographic primitives on the secp256k1 elliptic curve.
 
 This library is intended to be the highest quality publicly available library for cryptography on the secp256k1 curve. However, the primary focus of its development has been for usage in the Bitcoin system and usage unlike Bitcoin's may be less well tested, verified, or suffer from a less well thought out interface. Correct usage requires some care and consideration that the library is fit for your application's purpose.
 
@@ -34,7 +33,7 @@ Implementation details
   * Expose only higher level interfaces to minimize the API surface and improve application security. ("Be difficult to use insecurely.")
 * Field operations
   * Optimized implementation of arithmetic modulo the curve's field size (2^256 - 0x1000003D1).
-    * Using 5 52-bit limbs (including hand-optimized assembly for x86_64, by Diederik Huys).
+    * Using 5 52-bit limbs
     * Using 10 26-bit limbs (including hand-optimized assembly for 32-bit ARM, by Wladimir J. van der Laan).
       * This is an experimental feature that has not received enough scrutiny to satisfy the standard of quality of this library but is made available for testing and review by the community.
 * Scalar operations
@@ -60,10 +59,8 @@ Implementation details
   * Optional runtime blinding which attempts to frustrate differential power analysis.
   * The precomputed tables add and eventually subtract points for which no known scalar (secret key) is known, preventing even an attacker with control over the secret key used to control the data internally.
 
-Build steps
------------
-
-libsecp256k1 is built using autotools:
+Building with Autotools
+-----------------------
 
     $ ./autogen.sh
     $ ./configure
@@ -73,6 +70,43 @@ libsecp256k1 is built using autotools:
 
 To compile optional modules (such as Schnorr signatures), you need to run `./configure` with additional flags (such as `--enable-module-schnorrsig`). Run `./configure --help` to see the full list of available flags.
 
+Building with CMake (experimental)
+----------------------------------
+
+To maintain a pristine source tree, CMake encourages to perform an out-of-source build by using a separate dedicated build tree.
+
+### Building on POSIX systems
+
+    $ mkdir build && cd build
+    $ cmake ..
+    $ make
+    $ make check  # run the test suite
+    $ sudo make install  # optional
+
+To compile optional modules (such as Schnorr signatures), you need to run `cmake` with additional flags (such as `-DSECP256K1_ENABLE_MODULE_SCHNORRSIG=ON`). Run `cmake .. -LH` to see the full list of available flags.
+
+### Cross compiling
+
+To alleviate issues with cross compiling, preconfigured toolchain files are available in the `cmake` directory.
+For example, to cross compile for Windows:
+
+    $ cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/x86_64-w64-mingw32.toolchain.cmake
+
+To cross compile for Android with [NDK](https://developer.android.com/ndk/guides/cmake) (using NDK's toolchain file, and assuming the `ANDROID_NDK_ROOT` environment variable has been set):
+
+    $ cmake .. -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_ROOT}/build/cmake/android.toolchain.cmake" -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=28
+
+### Building on Windows
+
+To build on Windows with Visual Studio, a proper [generator](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html#visual-studio-generators) must be specified for a new build tree.
+
+The following example assumes using of Visual Studio 2022 and CMake v3.21+.
+
+In "Developer Command Prompt for VS 2022":
+
+    >cmake -G "Visual Studio 17 2022" -A x64 -S . -B build
+    >cmake --build build --config RelWithDebInfo
+
 Usage examples
 -----------
 Usage examples can be found in the [examples](examples) directory. To compile them you need to configure with `--enable-examples`.
@@ -82,28 +116,6 @@ Usage examples can be found in the [examples](examples) directory. To compile th
 
 To compile the Schnorr signature and ECDH examples, you also need to configure with `--enable-module-schnorrsig` and `--enable-module-ecdh`.
 
-Test coverage
------------
-
-This library aims to have full coverage of the reachable lines and branches.
-
-To create a test coverage report, configure with `--enable-coverage` (use of GCC is necessary):
-
-    $ ./configure --enable-coverage
-
-Run the tests:
-
-    $ make check
-
-To create a report, `gcovr` is recommended, as it includes branch coverage reporting:
-
-    $ gcovr --exclude 'src/bench*' --print-summary
-
-To create a HTML report with coloured and annotated source code:
-
-    $ mkdir -p coverage
-    $ gcovr --exclude 'src/bench*' --html --html-details -o coverage/coverage.html
-
 Benchmark
 ------------
 If configured with `--enable-benchmark` (which is the default), binaries for benchmarking the libsecp256k1 functions will be present in the root directory after the build.
@@ -120,3 +132,8 @@ Reporting a vulnerability
 ------------
 
 See [SECURITY.md](SECURITY.md)
+
+Contributing to libsecp256k1
+------------
+
+See [CONTRIBUTING.md](CONTRIBUTING.md)

build-aux/m4/bitcoin_secp.m4

@@ -1,12 +1,31 @@
 dnl escape "$0x" below using the m4 quadrigaph @S|@, and escape it again with a \ for the shell.
-AC_DEFUN([SECP_64BIT_ASM_CHECK],[
+AC_DEFUN([SECP_X86_64_ASM_CHECK],[
 AC_MSG_CHECKING(for x86_64 assembly availability)
 AC_LINK_IFELSE([AC_LANG_PROGRAM([[
   #include <stdint.h>]],[[
   uint64_t a = 11, tmp;
   __asm__ __volatile__("movq \@S|@0x100000000,%1; mulq %%rsi" : "+a"(a) : "S"(tmp) : "cc", "%rdx");
-  ]])],[has_64bit_asm=yes],[has_64bit_asm=no])
-AC_MSG_RESULT([$has_64bit_asm])
+  ]])], [has_x86_64_asm=yes], [has_x86_64_asm=no])
+AC_MSG_RESULT([$has_x86_64_asm])
+])
+
+AC_DEFUN([SECP_ARM32_ASM_CHECK], [
+  AC_MSG_CHECKING(for ARM32 assembly availability)
+  SECP_ARM32_ASM_CHECK_CFLAGS_saved_CFLAGS="$CFLAGS"
+  CFLAGS="-x assembler"
+  AC_LINK_IFELSE([AC_LANG_SOURCE([[
+    .syntax unified
+    .eabi_attribute 24, 1
+    .eabi_attribute 25, 1
+    .text
+    .global main
+    main:
+      ldr r0, =0x002A
+      mov r7, #1
+      swi 0   
+    ]])], [has_arm32_asm=yes], [has_arm32_asm=no])
+  AC_MSG_RESULT([$has_arm32_asm])
+  CFLAGS="$SECP_ARM32_ASM_CHECK_CFLAGS_saved_CFLAGS"
 ])
 
 AC_DEFUN([SECP_VALGRIND_CHECK],[
@@ -20,7 +39,8 @@ if test x"$has_valgrind" != x"yes"; then
     #if defined(NVALGRIND)
     #  error "Valgrind does not support this platform."
     #endif
-  ]])], [has_valgrind=yes; AC_DEFINE(HAVE_VALGRIND,1,[Define this symbol if valgrind is installed, and it supports the host platform])])
+  ]])], [has_valgrind=yes])
+  CPPFLAGS="$CPPFLAGS_TEMP"
 fi
 AC_MSG_RESULT($has_valgrind)
 ])

ci/ci.sh

@@ -0,0 +1,146 @@
+#!/bin/sh
+
+set -eux
+
+export LC_ALL=C
+
+# Print commit and relevant CI environment to allow reproducing the job outside of CI.
+git show --no-patch
+print_environment() {
+    # Turn off -x because it messes up the output
+    set +x
+    # There are many ways to print variable names and their content. This one
+    # does not rely on bash.
+    for var in WERROR_CFLAGS MAKEFLAGS BUILD \
+            ECMULTWINDOW ECMULTGENPRECISION ASM WIDEMUL WITH_VALGRIND EXTRAFLAGS \
+            EXPERIMENTAL ECDH RECOVERY SCHNORRSIG ELLSWIFT \
+            SECP256K1_TEST_ITERS BENCH SECP256K1_BENCH_ITERS CTIMETESTS\
+            EXAMPLES \
+            HOST WRAPPER_CMD \
+            CC CFLAGS CPPFLAGS AR NM
+    do
+        eval "isset=\${$var+x}"
+        if [ -n "$isset" ]; then
+            eval "val=\${$var}"
+            # shellcheck disable=SC2154
+            printf '%s="%s" ' "$var" "$val"
+        fi
+    done
+    echo "$0"
+    set -x
+}
+print_environment
+
+env >> test_env.log
+
+# If gcc is requested, assert that it's in fact gcc (and not some symlinked Apple clang).
+case "${CC:-undefined}" in
+    *gcc*)
+        $CC -v 2>&1 | grep -q "gcc version" || exit 1;
+        ;;
+esac
+
+if [ -n "${CC+x}" ]; then
+    # The MSVC compiler "cl" doesn't understand "-v"
+    $CC -v || true
+fi
+if [ "$WITH_VALGRIND" = "yes" ]; then
+    valgrind --version
+fi
+if [ -n "$WRAPPER_CMD" ]; then
+    $WRAPPER_CMD --version
+fi
+
+# Workaround for https://bugs.kde.org/show_bug.cgi?id=452758 (fixed in valgrind 3.20.0).
+case "${CC:-undefined}" in
+    clang*)
+        if [ "$CTIMETESTS" = "yes" ] && [ "$WITH_VALGRIND" = "yes" ]
+        then
+            export CFLAGS="${CFLAGS:+$CFLAGS }-gdwarf-4"
+        else
+            case "$WRAPPER_CMD" in
+                valgrind*)
+                    export CFLAGS="${CFLAGS:+$CFLAGS }-gdwarf-4"
+                    ;;
+            esac
+        fi
+        ;;
+esac
+
+./autogen.sh
+
+./configure \
+    --enable-experimental="$EXPERIMENTAL" \
+    --with-test-override-wide-multiply="$WIDEMUL" --with-asm="$ASM" \
+    --with-ecmult-window="$ECMULTWINDOW" \
+    --with-ecmult-gen-precision="$ECMULTGENPRECISION" \
+    --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" \
+    --enable-module-ellswift="$ELLSWIFT" \
+    --enable-module-schnorrsig="$SCHNORRSIG" \
+    --enable-examples="$EXAMPLES" \
+    --enable-ctime-tests="$CTIMETESTS" \
+    --with-valgrind="$WITH_VALGRIND" \
+    --host="$HOST" $EXTRAFLAGS
+
+# We have set "-j<n>" in MAKEFLAGS.
+build_exit_code=0
+make > make.log 2>&1 || build_exit_code=$?
+cat make.log
+if [ $build_exit_code -ne 0 ]; then
+    case "${CC:-undefined}" in
+        *snapshot*)
+            # Ignore internal compiler errors in gcc-snapshot and clang-snapshot
+            grep -e "internal compiler error:" -e "PLEASE submit a bug report" make.log
+            return $?;
+            ;;
+        *)
+            return 1;
+            ;;
+    esac
+fi
+
+# Print information about binaries so that we can see that the architecture is correct
+file *tests* || true
+file bench* || true
+file .libs/* || true
+
+# This tells `make check` to wrap test invocations.
+export LOG_COMPILER="$WRAPPER_CMD"
+
+make "$BUILD"
+
+# Using the local `libtool` because on macOS the system's libtool has nothing to do with GNU libtool
+EXEC='./libtool --mode=execute'
+if [ -n "$WRAPPER_CMD" ]
+then
+    EXEC="$EXEC $WRAPPER_CMD"
+fi
+
+if [ "$BENCH" = "yes" ]
+then
+    {
+        $EXEC ./bench_ecmult
+        $EXEC ./bench_internal
+        $EXEC ./bench
+    } >> bench.log 2>&1
+fi
+
+if [ "$CTIMETESTS" = "yes" ]
+then
+    if [ "$WITH_VALGRIND" = "yes" ]; then
+        ./libtool --mode=execute valgrind --error-exitcode=42 ./ctime_tests > ctime_tests.log 2>&1
+    else
+        $EXEC ./ctime_tests > ctime_tests.log 2>&1
+    fi
+fi
+
+# Rebuild precomputed files (if not cross-compiling).
+if [ -z "$HOST" ]
+then
+    make clean-precomp clean-testvectors
+    make precomp testvectors
+fi
+
+# Check that no repo files have been modified by the build.
+# (This fails for example if the precomp files need to be updated in the repo.)
+git diff --exit-code

ci/cirrus.sh

@@ -1,108 +0,0 @@
-#!/bin/sh
-
-set -e
-set -x
-
-export LC_ALL=C
-
-# Print relevant CI environment to allow reproducing the job outside of CI.
-print_environment() {
-    # Turn off -x because it messes up the output
-    set +x
-    # There are many ways to print variable names and their content. This one
-    # does not rely on bash.
-    for i in WERROR_CFLAGS MAKEFLAGS BUILD \
-            ECMULTWINDOW ECMULTGENPRECISION ASM WIDEMUL WITH_VALGRIND EXTRAFLAGS \
-            EXPERIMENTAL ECDH RECOVERY SCHNORRSIG \
-            SECP256K1_TEST_ITERS BENCH SECP256K1_BENCH_ITERS CTIMETEST\
-            EXAMPLES \
-            WRAPPER_CMD CC AR NM HOST
-    do
-        eval 'printf "%s %s " "$i=\"${'"$i"'}\""'
-    done
-    echo "$0"
-    set -x
-}
-print_environment
-
-# Start persistent wineserver if necessary.
-# This speeds up jobs with many invocations of wine (e.g., ./configure with MSVC) tremendously.
-case "$WRAPPER_CMD" in
-    *wine*)
-        # This is apparently only reliable when we run a dummy command such as "hh.exe" afterwards.
-        wineserver -p && wine hh.exe
-        ;;
-esac
-
-env >> test_env.log
-
-if [ -n "$CC" ]; then
-    # The MSVC compiler "cl" doesn't understand "-v"
-    $CC -v || true
-fi
-if [ "$WITH_VALGRIND" = "yes" ]; then
-    valgrind --version
-fi
-if [ -n "$WRAPPER_CMD" ]; then
-    $WRAPPER_CMD --version
-fi
-
-./autogen.sh
-
-./configure \
-    --enable-experimental="$EXPERIMENTAL" \
-    --with-test-override-wide-multiply="$WIDEMUL" --with-asm="$ASM" \
-    --with-ecmult-window="$ECMULTWINDOW" \
-    --with-ecmult-gen-precision="$ECMULTGENPRECISION" \
-    --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" \
-    --enable-module-schnorrsig="$SCHNORRSIG" \
-    --enable-examples="$EXAMPLES" \
-    --with-valgrind="$WITH_VALGRIND" \
-    --host="$HOST" $EXTRAFLAGS
-
-# We have set "-j<n>" in MAKEFLAGS.
-make
-
-# Print information about binaries so that we can see that the architecture is correct
-file *tests* || true
-file bench* || true
-file .libs/* || true
-
-# This tells `make check` to wrap test invocations.
-export LOG_COMPILER="$WRAPPER_CMD"
-
-make "$BUILD"
-
-if [ "$BENCH" = "yes" ]
-then
-    # Using the local `libtool` because on macOS the system's libtool has nothing to do with GNU libtool
-    EXEC='./libtool --mode=execute'
-    if [ -n "$WRAPPER_CMD" ]
-    then
-        EXEC="$EXEC $WRAPPER_CMD"
-    fi
-    {
-        $EXEC ./bench_ecmult
-        $EXEC ./bench_internal
-        $EXEC ./bench
-    } >> bench.log 2>&1
-fi
-
-if [ "$CTIMETEST" = "yes" ]
-then
-    ./libtool --mode=execute valgrind --error-exitcode=42 ./valgrind_ctime_test > valgrind_ctime_test.log 2>&1
-fi
-
-# Rebuild precomputed files (if not cross-compiling).
-if [ -z "$HOST" ]
-then
-    make clean-precomp
-    make precomp
-fi
-
-# Shutdown wineserver again
-wineserver -k || true
-
-# Check that no repo files have been modified by the build.
-# (This fails for example if the precomp files need to be updated in the repo.)
-git diff --exit-code

ci/linux-debian.Dockerfile

@@ -1,4 +1,17 @@
-FROM debian:stable
+FROM debian:stable-slim
+
+SHELL ["/bin/bash", "-c"]
+
+WORKDIR /root
+
+# A too high maximum number of file descriptors (with the default value
+# inherited from the docker host) can cause issues with some of our tools:
+#  - sanitizers hanging: https://github.com/google/sanitizers/issues/1662 
+#  - valgrind crashing: https://stackoverflow.com/a/75293014
+# This is not be a problem on our CI hosts, but developers who run the image
+# on their machines may run into this (e.g., on Arch Linux), so warn them.
+# (Note that .bashrc is only executed in interactive bash shells.)
+RUN echo 'if [[ $(ulimit -n) -gt 200000 ]]; then echo "WARNING: Very high value reported by \"ulimit -n\". Consider passing \"--ulimit nofile=32768\" to \"docker run\"."; fi' >> /root/.bashrc
 
 RUN dpkg --add-architecture i386 && \
     dpkg --add-architecture s390x && \
@@ -11,27 +24,56 @@ RUN dpkg --add-architecture i386 && \
 RUN apt-get update && apt-get install --no-install-recommends -y \
         git ca-certificates \
         make automake libtool pkg-config dpkg-dev valgrind qemu-user \
-        gcc clang llvm libc6-dbg \
+        gcc clang llvm libclang-rt-dev libc6-dbg \
         g++ \
-        gcc-i686-linux-gnu libc6-dev-i386-cross libc6-dbg:i386 libubsan1:i386 libasan6:i386 \
+        gcc-i686-linux-gnu libc6-dev-i386-cross libc6-dbg:i386 libubsan1:i386 libasan8:i386 \
         gcc-s390x-linux-gnu libc6-dev-s390x-cross libc6-dbg:s390x \
         gcc-arm-linux-gnueabihf libc6-dev-armhf-cross libc6-dbg:armhf \
-        gcc-aarch64-linux-gnu libc6-dev-arm64-cross libc6-dbg:arm64 \
         gcc-powerpc64le-linux-gnu libc6-dev-ppc64el-cross libc6-dbg:ppc64el \
         gcc-mingw-w64-x86-64-win32 wine64 wine \
         gcc-mingw-w64-i686-win32 wine32 \
-        sagemath
+        python3 && \
+        if ! ( dpkg --print-architecture | grep --quiet "arm64" ) ; then \
+         apt-get install --no-install-recommends -y \
+         gcc-aarch64-linux-gnu libc6-dev-arm64-cross libc6-dbg:arm64 ;\
+        fi && \
+        apt-get clean && rm -rf /var/lib/apt/lists/*
 
-WORKDIR /root
-# The "wine" package provides a convience wrapper that we need
-RUN apt-get update && apt-get install --no-install-recommends -y \
-        git ca-certificates wine64 wine python3-simplejson python3-six msitools winbind procps && \
-    git clone https://github.com/mstorsjo/msvc-wine && \
-    mkdir /opt/msvc && \
-    python3 msvc-wine/vsdownload.py --accept-license --dest /opt/msvc Microsoft.VisualStudio.Workload.VCTools && \
-    msvc-wine/install.sh /opt/msvc
+# Build and install gcc snapshot
+ARG GCC_SNAPSHOT_MAJOR=14
+RUN apt-get update && apt-get install --no-install-recommends -y wget libgmp-dev libmpfr-dev libmpc-dev flex && \
+    mkdir gcc && cd gcc && \
+    wget --progress=dot:giga --https-only --recursive --accept '*.tar.xz' --level 1 --no-directories "https://gcc.gnu.org/pub/gcc/snapshots/LATEST-${GCC_SNAPSHOT_MAJOR}" && \
+    wget "https://gcc.gnu.org/pub/gcc/snapshots/LATEST-${GCC_SNAPSHOT_MAJOR}/sha512.sum" && \
+    sha512sum --check --ignore-missing sha512.sum && \
+    # We should have downloaded exactly one tar.xz file
+    ls && \
+    [ $(ls *.tar.xz | wc -l) -eq "1" ] && \
+    tar xf *.tar.xz && \
+    mkdir gcc-build && cd gcc-build && \
+    ../*/configure --prefix=/opt/gcc-snapshot --enable-languages=c --disable-bootstrap --disable-multilib --without-isl && \
+    make -j $(nproc) && \
+    make install && \
+    cd ../.. && rm -rf gcc && \
+    ln -s /opt/gcc-snapshot/bin/gcc /usr/bin/gcc-snapshot && \
+    apt-get autoremove -y wget libgmp-dev libmpfr-dev libmpc-dev flex && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Install clang snapshot, see https://apt.llvm.org/
+RUN \
+    # Setup GPG keys of LLVM repository
+    apt-get update && apt-get install --no-install-recommends -y wget && \
+    wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc && \
+    # Add repository for this Debian release
+    . /etc/os-release && echo "deb http://apt.llvm.org/${VERSION_CODENAME} llvm-toolchain-${VERSION_CODENAME} main" >> /etc/apt/sources.list && \
+    apt-get update && \
+    # Determine the version number of the LLVM development branch
+    LLVM_VERSION=$(apt-cache search --names-only '^clang-[0-9]+$' | sort -V | tail -1 | cut -f1 -d" " | cut -f2 -d"-" ) && \
+    # Install
+    apt-get install --no-install-recommends -y "clang-${LLVM_VERSION}" && \
+    # Create symlink
+    ln -s "/usr/bin/clang-${LLVM_VERSION}" /usr/bin/clang-snapshot && \
+    # Clean up
+    apt-get autoremove -y wget && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
 
-# Initialize the wine environment. Wait until the wineserver process has
-# exited before closing the session, to avoid corrupting the wine prefix.
-RUN wine64 wineboot --init && \
-    while (ps -A | grep wineserver) > /dev/null; do sleep 1; done

cmake/CheckArm32Assembly.cmake

@@ -0,0 +1,6 @@
+function(check_arm32_assembly)
+  try_compile(HAVE_ARM32_ASM
+    ${CMAKE_BINARY_DIR}/check_arm32_assembly
+    SOURCES ${CMAKE_SOURCE_DIR}/cmake/source_arm32.s
+  )
+endfunction()

cmake/CheckStringOptionValue.cmake

@@ -0,0 +1,10 @@
+function(check_string_option_value option)
+  get_property(expected_values CACHE ${option} PROPERTY STRINGS)
+  if(expected_values)
+    if(${option} IN_LIST expected_values)
+      return()
+    endif()
+    message(FATAL_ERROR "${option} value is \"${${option}}\", but must be one of ${expected_values}.")
+  endif()
+  message(AUTHOR_WARNING "The STRINGS property must be set before invoking `check_string_option_value' function.")
+endfunction()

cmake/CheckX86_64Assembly.cmake

@@ -0,0 +1,14 @@
+include(CheckCSourceCompiles)
+
+function(check_x86_64_assembly)
+  check_c_source_compiles("
+    #include <stdint.h>
+
+    int main()
+    {
+      uint64_t a = 11, tmp;
+      __asm__ __volatile__(\"movq $0x100000000,%1; mulq %%rsi\" : \"+a\"(a) : \"S\"(tmp) : \"cc\", \"%rdx\");
+    }
+  " HAVE_X86_64_ASM)
+  set(HAVE_X86_64_ASM ${HAVE_X86_64_ASM} PARENT_SCOPE)
+endfunction()

cmake/FindValgrind.cmake

@@ -0,0 +1,41 @@
+if(CMAKE_HOST_APPLE)
+  find_program(BREW_COMMAND brew)
+  execute_process(
+    COMMAND ${BREW_COMMAND} --prefix valgrind
+    OUTPUT_VARIABLE valgrind_brew_prefix
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+  )
+endif()
+
+set(hints_paths)
+if(valgrind_brew_prefix)
+  set(hints_paths ${valgrind_brew_prefix}/include)
+endif()
+
+find_path(Valgrind_INCLUDE_DIR
+  NAMES valgrind/memcheck.h
+  HINTS ${hints_paths}
+)
+
+if(Valgrind_INCLUDE_DIR)
+  include(CheckCSourceCompiles)
+  set(CMAKE_REQUIRED_INCLUDES ${Valgrind_INCLUDE_DIR})
+  check_c_source_compiles("
+    #include <valgrind/memcheck.h>
+    #if defined(NVALGRIND)
+    #  error \"Valgrind does not support this platform.\"
+    #endif
+
+    int main() {}
+  " Valgrind_WORKS)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Valgrind
+  REQUIRED_VARS Valgrind_INCLUDE_DIR Valgrind_WORKS
+)
+
+mark_as_advanced(
+  Valgrind_INCLUDE_DIR
+)

cmake/GeneratePkgConfigFile.cmake

@@ -0,0 +1,8 @@
+function(generate_pkg_config_file in_file)
+  set(prefix ${CMAKE_INSTALL_PREFIX})
+  set(exec_prefix \${prefix})
+  set(libdir \${exec_prefix}/${CMAKE_INSTALL_LIBDIR})
+  set(includedir \${prefix}/${CMAKE_INSTALL_INCLUDEDIR})
+  set(PACKAGE_VERSION ${PROJECT_VERSION})
+  configure_file(${in_file} ${PROJECT_NAME}.pc @ONLY)
+endfunction()

cmake/TryAppendCFlags.cmake

@@ -0,0 +1,24 @@
+include(CheckCCompilerFlag)
+
+function(secp256k1_check_c_flags_internal flags output)
+  string(MAKE_C_IDENTIFIER "${flags}" result)
+  string(TOUPPER "${result}" result)
+  set(result "C_SUPPORTS_${result}")
+  if(NOT MSVC)
+    set(CMAKE_REQUIRED_FLAGS "-Werror")
+  endif()
+
+  # This avoids running a linker.
+  set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+  check_c_compiler_flag("${flags}" ${result})
+
+  set(${output} ${${result}} PARENT_SCOPE)
+endfunction()
+
+# Append flags to the COMPILE_OPTIONS directory property if CC accepts them.
+macro(try_append_c_flags)
+  secp256k1_check_c_flags_internal("${ARGV}" result)
+  if(result)
+    add_compile_options(${ARGV})
+  endif()
+endmacro()

cmake/arm-linux-gnueabihf.toolchain.cmake

@@ -0,0 +1,3 @@
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR arm)
+set(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)

cmake/config.cmake.in

@@ -0,0 +1,5 @@
+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@-targets.cmake")
+
+check_required_components(@PROJECT_NAME@)

cmake/source_arm32.s

@@ -0,0 +1,9 @@
+.syntax unified
+.eabi_attribute 24, 1
+.eabi_attribute 25, 1
+.text
+.global main
+main:
+	ldr	r0, =0x002A
+	mov	r7, #1
+	swi	0   

cmake/x86_64-w64-mingw32.toolchain.cmake

@@ -0,0 +1,3 @@
+set(CMAKE_SYSTEM_NAME Windows)
+set(CMAKE_SYSTEM_PROCESSOR x86_64)
+set(CMAKE_C_COMPILER x86_64-w64-mingw32-gcc)

configure.ac

@@ -4,8 +4,8 @@ AC_PREREQ([2.60])
 # the API. All changes in experimental modules are treated as
 # backwards-compatible and therefore at most increase the minor version.
 define(_PKG_VERSION_MAJOR, 0)
-define(_PKG_VERSION_MINOR, 2)
-define(_PKG_VERSION_PATCH, 0)
+define(_PKG_VERSION_MINOR, 4)
+define(_PKG_VERSION_PATCH, 1)
 define(_PKG_VERSION_IS_RELEASE, true)
 
 # The library version is based on libtool versioning of the ABI. The set of
@@ -13,18 +13,15 @@ define(_PKG_VERSION_IS_RELEASE, true)
 # https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
 # All changes in experimental modules are treated as if they don't affect the
 # interface and therefore only increase the revision.
-define(_LIB_VERSION_CURRENT, 1)
-define(_LIB_VERSION_REVISION, 0)
-define(_LIB_VERSION_AGE, 0)
+define(_LIB_VERSION_CURRENT, 3)
+define(_LIB_VERSION_REVISION, 1)
+define(_LIB_VERSION_AGE, 1)
 
 AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_PATCH)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-dev]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1])
 
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
 AC_CANONICAL_HOST
-AH_TOP([#ifndef LIBSECP256K1_CONFIG_H])
-AH_TOP([#define LIBSECP256K1_CONFIG_H])
-AH_BOTTOM([#endif /*LIBSECP256K1_CONFIG_H*/])
 
 # Require Automake 1.11.2 for AM_PROG_AR
 AM_INIT_AUTOMAKE([1.11.2 foreign subdir-objects])
@@ -32,6 +29,11 @@ AM_INIT_AUTOMAKE([1.11.2 foreign subdir-objects])
 # Make the compilation flags quiet unless V=1 is used.
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
+if test "${CFLAGS+set}" = "set"; then
+  CFLAGS_overridden=yes
+else
+  CFLAGS_overridden=no
+fi
 AC_PROG_CC
 AM_PROG_AS
 AM_PROG_AR
@@ -91,11 +93,14 @@ esac
 AC_DEFUN([SECP_TRY_APPEND_DEFAULT_CFLAGS], [
     # GCC and compatible (incl. clang)
     if test "x$GCC" = "xyes"; then
-      # Try to append -Werror=unknown-warning-option to CFLAGS temporarily. Otherwise clang will
-      # not error out if it gets unknown warning flags and the checks here will always succeed
-      # no matter if clang knows the flag or not.
+      # Try to append -Werror to CFLAGS temporarily. Otherwise checks for some unsupported
+      # flags will succeed.
+      # Note that failure to append -Werror does not necessarily mean that -Werror is not
+      # supported. The compiler may already be warning about something unrelated, for example
+      # about some path issue. If that is the case, -Werror cannot be used because all
+      # of those warnings would be turned into errors.
       SECP_TRY_APPEND_DEFAULT_CFLAGS_saved_CFLAGS="$CFLAGS"
-      SECP_TRY_APPEND_CFLAGS([-Werror=unknown-warning-option], CFLAGS)
+      SECP_TRY_APPEND_CFLAGS([-Werror], CFLAGS)
 
       SECP_TRY_APPEND_CFLAGS([-std=c89 -pedantic -Wno-long-long -Wnested-externs -Wshadow -Wstrict-prototypes -Wundef], $1) # GCC >= 3.0, -Wlong-long is implied by -pedantic.
       SECP_TRY_APPEND_CFLAGS([-Wno-overlength-strings], $1) # GCC >= 4.2, -Woverlength-strings is implied by -pedantic.
@@ -105,6 +110,7 @@ AC_DEFUN([SECP_TRY_APPEND_DEFAULT_CFLAGS], [
       SECP_TRY_APPEND_CFLAGS([-Wcast-align], $1) # GCC >= 2.95
       SECP_TRY_APPEND_CFLAGS([-Wcast-align=strict], $1) # GCC >= 8.0
       SECP_TRY_APPEND_CFLAGS([-Wconditional-uninitialized], $1) # Clang >= 3.0 only
+      SECP_TRY_APPEND_CFLAGS([-Wreserved-identifier], $1) # Clang >= 13.0 only
       SECP_TRY_APPEND_CFLAGS([-fvisibility=hidden], $1) # GCC >= 4.0
 
       CFLAGS="$SECP_TRY_APPEND_DEFAULT_CFLAGS_saved_CFLAGS"
@@ -115,8 +121,12 @@ AC_DEFUN([SECP_TRY_APPEND_DEFAULT_CFLAGS], [
     # libtool makes the same assumption internally.
     # Note that "/opt" and "-opt" are equivalent for MSVC; we use "-opt" because "/opt" looks like a path.
     if test x"$GCC" != x"yes" && test x"$build_windows" = x"yes"; then
-      SECP_TRY_APPEND_CFLAGS([-W2 -wd4146], $1) # Moderate warning level, disable warning C4146 "unary minus operator applied to unsigned type, result still unsigned"
-      SECP_TRY_APPEND_CFLAGS([-external:anglebrackets -external:W0], $1) # Suppress warnings from #include <...> files
+      SECP_TRY_APPEND_CFLAGS([-W3], $1) # Production quality warning level.
+      SECP_TRY_APPEND_CFLAGS([-wd4146], $1) # Disable warning C4146 "unary minus operator applied to unsigned type, result still unsigned".
+      SECP_TRY_APPEND_CFLAGS([-wd4244], $1) # Disable warning C4244 "'conversion' conversion from 'type1' to 'type2', possible loss of data".
+      SECP_TRY_APPEND_CFLAGS([-wd4267], $1) # Disable warning C4267 "'var' : conversion from 'size_t' to 'type', possible loss of data".
+      # Eliminate deprecation warnings for the older, less secure functions.
+      CPPFLAGS="-D_CRT_SECURE_NO_WARNINGS $CPPFLAGS"
     fi
 ])
 SECP_TRY_APPEND_DEFAULT_CFLAGS(SECP_CFLAGS)
@@ -142,6 +152,10 @@ AC_ARG_ENABLE(tests,
     AS_HELP_STRING([--enable-tests],[compile tests [default=yes]]), [],
     [SECP_SET_DEFAULT([enable_tests], [yes], [yes])])
 
+AC_ARG_ENABLE(ctime_tests,
+    AS_HELP_STRING([--enable-ctime-tests],[compile constant-time tests [default=yes if valgrind enabled]]), [],
+    [SECP_SET_DEFAULT([enable_ctime_tests], [auto], [auto])])
+
 AC_ARG_ENABLE(experimental,
     AS_HELP_STRING([--enable-experimental],[allow experimental configure options [default=no]]), [],
     [SECP_SET_DEFAULT([enable_experimental], [no], [yes])])
@@ -170,6 +184,10 @@ AC_ARG_ENABLE(module_schnorrsig,
     AS_HELP_STRING([--enable-module-schnorrsig],[enable schnorrsig module [default=yes]]), [],
     [SECP_SET_DEFAULT([enable_module_schnorrsig], [yes], [yes])])
 
+AC_ARG_ENABLE(module_ellswift,
+    AS_HELP_STRING([--enable-module-ellswift],[enable ElligatorSwift module [default=yes]]), [],
+    [SECP_SET_DEFAULT([enable_module_ellswift], [yes], [yes])])
+
 AC_ARG_ENABLE(external_default_callbacks,
     AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]), [],
     [SECP_SET_DEFAULT([enable_external_default_callbacks], [no], [no])])
@@ -182,8 +200,8 @@ AC_ARG_ENABLE(external_default_callbacks,
 #  *  and auto (the default).
 AC_ARG_WITH([test-override-wide-multiply], [] ,[set_widemul=$withval], [set_widemul=auto])
 
-AC_ARG_WITH([asm], [AS_HELP_STRING([--with-asm=x86_64|arm|no|auto],
-[assembly optimizations to use (experimental: arm) [default=auto]])],[req_asm=$withval], [req_asm=auto])
+AC_ARG_WITH([asm], [AS_HELP_STRING([--with-asm=x86_64|arm32|no|auto],
+[assembly to use (experimental: arm32) [default=auto]])],[req_asm=$withval], [req_asm=auto])
 
 AC_ARG_WITH([ecmult-window], [AS_HELP_STRING([--with-ecmult-window=SIZE|auto],
 [window size for ecmult precomputation for verification, specified as integer in range [2..24].]
@@ -225,11 +243,20 @@ else
     enable_valgrind=yes
   fi
 fi
-AM_CONDITIONAL([VALGRIND_ENABLED],[test "$enable_valgrind" = "yes"])
+
+if test x"$enable_ctime_tests" = x"auto"; then
+    enable_ctime_tests=$enable_valgrind
+fi
 
 if test x"$enable_coverage" = x"yes"; then
-    AC_DEFINE(COVERAGE, 1, [Define this symbol to compile out all VERIFY code])
+    SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DCOVERAGE=1"
     SECP_CFLAGS="-O0 --coverage $SECP_CFLAGS"
+    # If coverage is enabled, and the user has not overridden CFLAGS,
+    # override Autoconf's value "-g -O2" with "-g". Otherwise we'd end up
+    # with "-O0 --coverage -g -O2".
+    if test "$CFLAGS_overridden" = "no"; then
+      CFLAGS="-g"
+    fi
     LDFLAGS="--coverage $LDFLAGS"
 else
     # Most likely the CFLAGS already contain -O2 because that is autoconf's default.
@@ -239,8 +266,8 @@ else
 fi
 
 if test x"$req_asm" = x"auto"; then
-  SECP_64BIT_ASM_CHECK
-  if test x"$has_64bit_asm" = x"yes"; then
+  SECP_X86_64_ASM_CHECK
+  if test x"$has_x86_64_asm" = x"yes"; then
     set_asm=x86_64
   fi
   if test x"$set_asm" = x; then
@@ -250,53 +277,57 @@ else
   set_asm=$req_asm
   case $set_asm in
   x86_64)
-    SECP_64BIT_ASM_CHECK
-    if test x"$has_64bit_asm" != x"yes"; then
-      AC_MSG_ERROR([x86_64 assembly optimization requested but not available])
+    SECP_X86_64_ASM_CHECK
+    if test x"$has_x86_64_asm" != x"yes"; then
+      AC_MSG_ERROR([x86_64 assembly requested but not available])
     fi
     ;;
-  arm)
+  arm32)
+    SECP_ARM32_ASM_CHECK
+    if test x"$has_arm32_asm" != x"yes"; then
+      AC_MSG_ERROR([ARM32 assembly requested but not available])
+    fi
     ;;
   no)
     ;;
   *)
-    AC_MSG_ERROR([invalid assembly optimization selection])
+    AC_MSG_ERROR([invalid assembly selection])
     ;;
   esac
 fi
 
-# Select assembly optimization
+# Select assembly
 enable_external_asm=no
 
 case $set_asm in
 x86_64)
-  AC_DEFINE(USE_ASM_X86_64, 1, [Define this symbol to enable x86_64 assembly optimizations])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_ASM_X86_64=1"
   ;;
-arm)
+arm32)
   enable_external_asm=yes
   ;;
 no)
   ;;
 *)
-  AC_MSG_ERROR([invalid assembly optimizations])
+  AC_MSG_ERROR([invalid assembly selection])
   ;;
 esac
 
 if test x"$enable_external_asm" = x"yes"; then
-  AC_DEFINE(USE_EXTERNAL_ASM, 1, [Define this symbol if an external (non-inline) assembly implementation is used])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_EXTERNAL_ASM=1"
 fi
 
 
 # Select wide multiplication implementation
 case $set_widemul in
 int128_struct)
-  AC_DEFINE(USE_FORCE_WIDEMUL_INT128_STRUCT, 1, [Define this symbol to force the use of the structure for simulating (unsigned) int128 based wide multiplication])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_FORCE_WIDEMUL_INT128_STRUCT=1"
   ;;
 int128)
-  AC_DEFINE(USE_FORCE_WIDEMUL_INT128, 1, [Define this symbol to force the use of the (unsigned) __int128 based wide multiplication implementation])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_FORCE_WIDEMUL_INT128=1"
   ;;
 int64)
-  AC_DEFINE(USE_FORCE_WIDEMUL_INT64, 1, [Define this symbol to force the use of the (u)int64_t based wide multiplication implementation])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_FORCE_WIDEMUL_INT64=1"
   ;;
 auto)
   ;;
@@ -323,7 +354,7 @@ case $set_ecmult_window in
     # not in range
     AC_MSG_ERROR($error_window_size)
   fi
-  AC_DEFINE_UNQUOTED(ECMULT_WINDOW_SIZE, $set_ecmult_window, [Set window size for ecmult precomputation])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DECMULT_WINDOW_SIZE=$set_ecmult_window"
   ;;
 esac
 
@@ -336,7 +367,7 @@ fi
 
 case $set_ecmult_gen_precision in
 2|4|8)
-  AC_DEFINE_UNQUOTED(ECMULT_GEN_PREC_BITS, $set_ecmult_gen_precision, [Set ecmult gen precision bits])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DECMULT_GEN_PREC_BITS=$set_ecmult_gen_precision"
   ;;
 *)
   AC_MSG_ERROR(['ecmult gen precision not 2, 4, 8 or "auto"'])
@@ -344,7 +375,7 @@ case $set_ecmult_gen_precision in
 esac
 
 if test x"$enable_valgrind" = x"yes"; then
-  SECP_INCLUDES="$SECP_INCLUDES $VALGRIND_CPPFLAGS"
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES $VALGRIND_CPPFLAGS -DVALGRIND"
 fi
 
 # Add -Werror and similar flags passed from the outside (for testing, e.g., in CI).
@@ -357,26 +388,30 @@ SECP_CFLAGS="$SECP_CFLAGS $WERROR_CFLAGS"
 ###
 
 if test x"$enable_module_ecdh" = x"yes"; then
-  AC_DEFINE(ENABLE_MODULE_ECDH, 1, [Define this symbol to enable the ECDH module])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDH=1"
 fi
 
 if test x"$enable_module_recovery" = x"yes"; then
-  AC_DEFINE(ENABLE_MODULE_RECOVERY, 1, [Define this symbol to enable the ECDSA pubkey recovery module])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_RECOVERY=1"
 fi
 
 if test x"$enable_module_schnorrsig" = x"yes"; then
-  AC_DEFINE(ENABLE_MODULE_SCHNORRSIG, 1, [Define this symbol to enable the schnorrsig module])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_SCHNORRSIG=1"
   enable_module_extrakeys=yes
 fi
 
+if test x"$enable_module_ellswift" = x"yes"; then
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ELLSWIFT=1"
+fi
+
 # Test if extrakeys is set after the schnorrsig module to allow the schnorrsig
 # module to set enable_module_extrakeys=yes
 if test x"$enable_module_extrakeys" = x"yes"; then
-  AC_DEFINE(ENABLE_MODULE_EXTRAKEYS, 1, [Define this symbol to enable the extrakeys module])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_EXTRAKEYS=1"
 fi
 
 if test x"$enable_external_default_callbacks" = x"yes"; then
-  AC_DEFINE(USE_EXTERNAL_DEFAULT_CALLBACKS, 1, [Define this symbol if an external implementation of the default callbacks is used])
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1"
 fi
 
 ###
@@ -389,8 +424,8 @@ if test x"$enable_experimental" = x"yes"; then
   AC_MSG_NOTICE([Experimental features do not have stable APIs or properties, and may not be safe for production use.])
   AC_MSG_NOTICE([******])
 else
-  if test x"$set_asm" = x"arm"; then
-    AC_MSG_ERROR([ARM assembly optimization is experimental. Use --enable-experimental to allow.])
+  if test x"$set_asm" = x"arm32"; then
+    AC_MSG_ERROR([ARM32 assembly is experimental. Use --enable-experimental to allow.])
   fi
 fi
 
@@ -398,15 +433,12 @@ fi
 ### Generate output
 ###
 
-AC_CONFIG_HEADERS([src/libsecp256k1-config.h])
 AC_CONFIG_FILES([Makefile libsecp256k1.pc])
-AC_SUBST(SECP_INCLUDES)
-AC_SUBST(SECP_LIBS)
-AC_SUBST(SECP_TEST_LIBS)
-AC_SUBST(SECP_TEST_INCLUDES)
 AC_SUBST(SECP_CFLAGS)
+AC_SUBST(SECP_CONFIG_DEFINES)
 AM_CONDITIONAL([ENABLE_COVERAGE], [test x"$enable_coverage" = x"yes"])
 AM_CONDITIONAL([USE_TESTS], [test x"$enable_tests" != x"no"])
+AM_CONDITIONAL([USE_CTIME_TESTS], [test x"$enable_ctime_tests" = x"yes"])
 AM_CONDITIONAL([USE_EXHAUSTIVE_TESTS], [test x"$enable_exhaustive_tests" != x"no"])
 AM_CONDITIONAL([USE_EXAMPLES], [test x"$enable_examples" != x"no"])
 AM_CONDITIONAL([USE_BENCHMARK], [test x"$enable_benchmark" = x"yes"])
@@ -414,8 +446,9 @@ AM_CONDITIONAL([ENABLE_MODULE_ECDH], [test x"$enable_module_ecdh" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_RECOVERY], [test x"$enable_module_recovery" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_EXTRAKEYS], [test x"$enable_module_extrakeys" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"])
+AM_CONDITIONAL([ENABLE_MODULE_ELLSWIFT], [test x"$enable_module_ellswift" = x"yes"])
 AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$enable_external_asm" = x"yes"])
-AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm"])
+AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm32"])
 AM_CONDITIONAL([BUILD_WINDOWS], [test "$build_windows" = "yes"])
 AC_SUBST(LIB_VERSION_CURRENT, _LIB_VERSION_CURRENT)
 AC_SUBST(LIB_VERSION_REVISION, _LIB_VERSION_REVISION)
@@ -428,12 +461,14 @@ echo "Build Options:"
 echo "  with external callbacks = $enable_external_default_callbacks"
 echo "  with benchmarks         = $enable_benchmark"
 echo "  with tests              = $enable_tests"
+echo "  with ctime tests        = $enable_ctime_tests"
 echo "  with coverage           = $enable_coverage"
 echo "  with examples           = $enable_examples"
 echo "  module ecdh             = $enable_module_ecdh"
 echo "  module recovery         = $enable_module_recovery"
 echo "  module extrakeys        = $enable_module_extrakeys"
 echo "  module schnorrsig       = $enable_module_schnorrsig"
+echo "  module ellswift         = $enable_module_ellswift"
 echo
 echo "  asm                     = $set_asm"
 echo "  ecmult window size      = $set_ecmult_window"

doc/ellswift.md

@@ -0,0 +1,483 @@
+# ElligatorSwift for secp256k1 explained
+
+In this document we explain how the `ellswift` module implementation is related to the
+construction in the
+["SwiftEC: Shallue–van de Woestijne Indifferentiable Function To Elliptic Curves"](https://eprint.iacr.org/2022/759)
+paper by Jorge Chávez-Saab, Francisco Rodríguez-Henríquez, and Mehdi Tibouchi.
+
+* [1. Introduction](#1-introduction)
+* [2. The decoding function](#2-the-decoding-function)
+  + [2.1 Decoding for `secp256k1`](#21-decoding-for-secp256k1)
+* [3. The encoding function](#3-the-encoding-function)
+  + [3.1 Switching to *v, w* coordinates](#31-switching-to-v-w-coordinates)
+  + [3.2 Avoiding computing all inverses](#32-avoiding-computing-all-inverses)
+  + [3.3 Finding the inverse](#33-finding-the-inverse)
+  + [3.4 Dealing with special cases](#34-dealing-with-special-cases)
+  + [3.5 Encoding for `secp256k1`](#35-encoding-for-secp256k1)
+* [4. Encoding and decoding full *(x, y)* coordinates](#4-encoding-and-decoding-full-x-y-coordinates)
+  + [4.1 Full *(x, y)* coordinates for `secp256k1`](#41-full-x-y-coordinates-for-secp256k1)
+
+## 1. Introduction
+
+The `ellswift` module effectively introduces a new 64-byte public key format, with the property
+that (uniformly random) public keys can be encoded as 64-byte arrays which are computationally
+indistinguishable from uniform byte arrays. The module provides functions to convert public keys
+from and to this format, as well as convenience functions for key generation and ECDH that operate
+directly on ellswift-encoded keys.
+
+The encoding consists of the concatenation of two (32-byte big endian) encoded field elements $u$
+and $t.$ Together they encode an x-coordinate on the curve $x$, or (see further) a full point $(x, y)$ on
+the curve.
+
+**Decoding** consists of decoding the field elements $u$ and $t$ (values above the field size $p$
+are taken modulo $p$), and then evaluating $F_u(t)$, which for every $u$ and $t$ results in a valid
+x-coordinate on the curve. The functions $F_u$ will be defined in [Section 2](#2-the-decoding-function).
+
+**Encoding** a given $x$ coordinate is conceptually done as follows:
+* Loop:
+  * Pick a uniformly random field element $u.$
+  * Compute the set $L = F_u^{-1}(x)$ of $t$ values for which $F_u(t) = x$, which may have up to *8* elements.
+  * With probability $1 - \dfrac{\\#L}{8}$, restart the loop.
+  * Select a uniformly random $t \in L$ and return $(u, t).$
+
+This is the *ElligatorSwift* algorithm, here given for just x-coordinates. An extension to full
+$(x, y)$ points will be given in [Section 4](#4-encoding-and-decoding-full-x-y-coordinates).
+The algorithm finds a uniformly random $(u, t)$ among (almost all) those
+for which $F_u(t) = x.$ Section 3.2 in the paper proves that the number of such encodings for
+almost all x-coordinates on the curve (all but at most 39) is close to two times the field size
+(specifically, it lies in the range $2q \pm (22\sqrt{q} + O(1))$, where $q$ is the size of the field).
+
+## 2. The decoding function
+
+First some definitions:
+* $\mathbb{F}$ is the finite field of size $q$, of characteristic 5 or more, and $q \equiv 1 \mod 3.$
+  * For `secp256k1`, $q = 2^{256} - 2^{32} - 977$, which satisfies that requirement.
+* Let $E$ be the elliptic curve of points $(x, y) \in \mathbb{F}^2$ for which $y^2 = x^3 + ax + b$, with $a$ and $b$
+  public constants, for which $\Delta_E = -16(4a^3 + 27b^2)$ is a square, and at least one of $(-b \pm \sqrt{-3 \Delta_E} / 36)/2$ is a square.
+  This implies that the order of $E$ is either odd, or a multiple of *4*.
+  If $a=0$, this condition is always fulfilled.
+  * For `secp256k1`, $a=0$ and $b=7.$
+* Let the function $g(x) = x^3 + ax + b$, so the $E$ curve equation is also $y^2 = g(x).$
+* Let the function $h(x) = 3x^3 + 4a.$
+* Define $V$ as the set of solutions $(x_1, x_2, x_3, z)$ to $z^2 = g(x_1)g(x_2)g(x_3).$
+* Define $S_u$ as the set of solutions $(X, Y)$ to $X^2 + h(u)Y^2 = -g(u)$ and $Y \neq 0.$
+* $P_u$ is a function from $\mathbb{F}$ to $S_u$ that will be defined below.
+* $\psi_u$ is a function from $S_u$ to $V$ that will be defined below.
+
+**Note**: In the paper:
+* $F_u$ corresponds to $F_{0,u}$ there.
+* $P_u(t)$ is called $P$ there.
+* All $S_u$ sets together correspond to $S$ there.
+* All $\psi_u$ functions together (operating on elements of $S$) correspond to $\psi$ there.
+
+Note that for $V$, the left hand side of the equation $z^2$ is square, and thus the right
+hand must also be square. As multiplying non-squares results in a square in $\mathbb{F}$,
+out of the three right-hand side factors an even number must be non-squares.
+This implies that exactly *1* or exactly *3* out of
+$\\{g(x_1), g(x_2), g(x_3)\\}$ must be square, and thus that for any $(x_1,x_2,x_3,z) \in V$,
+at least one of $\\{x_1, x_2, x_3\\}$ must be a valid x-coordinate on $E.$ There is one exception
+to this, namely when $z=0$, but even then one of the three values is a valid x-coordinate.
+
+**Define** the decoding function $F_u(t)$ as:
+* Let $(x_1, x_2, x_3, z) = \psi_u(P_u(t)).$
+* Return the first element $x$ of $(x_3, x_2, x_1)$ which is a valid x-coordinate on $E$ (i.e., $g(x)$ is square).
+
+$P_u(t) = (X(u, t), Y(u, t))$, where:
+
+$$
+\begin{array}{lcl}
+X(u, t) & = & \left\\{\begin{array}{ll}
+  \dfrac{g(u) - t^2}{2t} & a = 0 \\
+  \dfrac{g(u) + h(u)(Y_0(u) - X_0(u)t)^2}{X_0(u)(1 + h(u)t^2)} & a \neq 0
+\end{array}\right. \\
+Y(u, t) & = & \left\\{\begin{array}{ll}
+  \dfrac{X(u, t) + t}{u \sqrt{-3}} = \dfrac{g(u) + t^2}{2tu\sqrt{-3}} & a = 0 \\
+  Y_0(u) + t(X(u, t) - X_0(u)) & a \neq 0
+\end{array}\right.
+\end{array}
+$$
+
+$P_u(t)$ is defined:
+* For $a=0$, unless:
+  * $u = 0$ or $t = 0$ (division by zero)
+  * $g(u) = -t^2$ (would give $Y=0$).
+* For $a \neq 0$, unless:
+  * $X_0(u) = 0$ or $h(u)t^2 = -1$ (division by zero)
+  * $Y_0(u) (1 - h(u)t^2) = 2X_0(u)t$ (would give $Y=0$).
+
+The functions $X_0(u)$ and $Y_0(u)$ are defined in Appendix A of the paper, and depend on various properties of $E.$
+
+The function $\psi_u$ is the same for all curves: $\psi_u(X, Y) = (x_1, x_2, x_3, z)$, where:
+
+$$
+\begin{array}{lcl}
+  x_1 & = & \dfrac{X}{2Y} - \dfrac{u}{2} && \\
+  x_2 & = & -\dfrac{X}{2Y} - \dfrac{u}{2} && \\
+  x_3 & = & u + 4Y^2 && \\
+  z   & = & \dfrac{g(x_3)}{2Y}(u^2 + ux_1 + x_1^2 + a) = \dfrac{-g(u)g(x_3)}{8Y^3}
+\end{array}
+$$
+
+### 2.1 Decoding for `secp256k1`
+
+Put together and specialized for $a=0$ curves, decoding $(u, t)$ to an x-coordinate is:
+
+**Define** $F_u(t)$ as:
+* Let $X = \dfrac{u^3 + b - t^2}{2t}.$
+* Let $Y = \dfrac{X + t}{u\sqrt{-3}}.$
+* Return the first $x$ in $(u + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u}{2}, \dfrac{X}{2Y} - \dfrac{u}{2})$ for which $g(x)$ is square.
+
+To make sure that every input decodes to a valid x-coordinate, we remap the inputs in case
+$P_u$ is not defined (when $u=0$, $t=0$, or $g(u) = -t^2$):
+
+**Define** $F_u(t)$ as:
+* Let $u'=u$ if $u \neq 0$; $1$ otherwise (guaranteeing $u' \neq 0$).
+* Let $t'=t$ if $t \neq 0$; $1$ otherwise (guaranteeing $t' \neq 0$).
+* Let $t''=t'$ if $g(u') \neq -t'^2$; $2t'$ otherwise (guaranteeing $t'' \neq 0$ and $g(u') \neq -t''^2$).
+* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$
+* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$
+* Return the first $x$ in $(u' + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u'}{2}, \dfrac{X}{2Y} - \dfrac{u'}{2})$ for which $x^3 + b$ is square.
+
+The choices here are not strictly necessary. Just returning a fixed constant in any of the undefined cases would suffice,
+but the approach here is simple enough and gives fairly uniform output even in these cases.
+
+**Note**: in the paper these conditions result in $\infty$ as output, due to the use of projective coordinates there.
+We wish to avoid the need for callers to deal with this special case.
+
+This is implemented in `secp256k1_ellswift_xswiftec_frac_var` (which decodes to an x-coordinate represented as a fraction), and
+in `secp256k1_ellswift_xswiftec_var` (which outputs the actual x-coordinate).
+
+## 3. The encoding function
+
+To implement $F_u^{-1}(x)$, the function to find the set of inverses $t$ for which $F_u(t) = x$, we have to reverse the process:
+* Find all the $(X, Y) \in S_u$ that could have given rise to $x$, through the $x_1$, $x_2$, or $x_3$ formulas in $\psi_u.$
+* Map those $(X, Y)$ solutions to $t$ values using $P_u^{-1}(X, Y).$
+* For each of the found $t$ values, verify that $F_u(t) = x.$
+* Return the remaining $t$ values.
+
+The function $P_u^{-1}$, which finds $t$ given $(X, Y) \in S_u$, is significantly simpler than $P_u:$
+
+$$
+P_u^{-1}(X, Y) = \left\\{\begin{array}{ll}
+Yu\sqrt{-3} - X & a = 0 \\
+\dfrac{Y-Y_0(u)}{X-X_0(u)} & a \neq 0 \land X \neq X_0(u) \\
+\dfrac{-X_0(u)}{h(u)Y_0(u)} & a \neq 0 \land X = X_0(u) \land Y = Y_0(u)
+\end{array}\right.
+$$
+
+The third step above, verifying that $F_u(t) = x$, is necessary because for the $(X, Y)$ values found through the $x_1$ and $x_2$ expressions,
+it is possible that decoding through $\psi_u(X, Y)$ yields a valid $x_3$ on the curve, which would take precedence over the
+$x_1$ or $x_2$ decoding. These $(X, Y)$ solutions must be rejected.
+
+Since we know that exactly one or exactly three out of $\\{x_1, x_2, x_3\\}$ are valid x-coordinates for any $t$,
+the case where either $x_1$ or $x_2$ is valid and in addition also $x_3$ is valid must mean that all three are valid.
+This means that instead of checking whether $x_3$ is on the curve, it is also possible to check whether the other one out of
+$x_1$ and $x_2$ is on the curve. This is significantly simpler, as it turns out.
+
+Observe that $\psi_u$ guarantees that $x_1 + x_2 = -u.$ So given either $x = x_1$ or $x = x_2$, the other one of the two can be computed as
+$-u - x.$ Thus, when encoding $x$ through the $x_1$ or $x_2$ expressions, one can simply check whether $g(-u-x)$ is a square,
+and if so, not include the corresponding $t$ values in the returned set. As this does not need $X$, $Y$, or $t$, this condition can be determined
+before those values are computed.
+
+It is not possible that an encoding found through the $x_1$ expression decodes to a different valid x-coordinate using $x_2$ (which would
+take precedence), for the same reason: if both $x_1$ and $x_2$ decodings were valid, $x_3$ would be valid as well, and thus take
+precedence over both. Because of this, the $g(-u-x)$ being square test for $x_1$ and $x_2$ is the only test necessary to guarantee the found $t$
+values round-trip back to the input $x$ correctly. This is the reason for choosing the $(x_3, x_2, x_1)$ precedence order in the decoder;
+any order which does not place $x_3$ first requires more complicated round-trip checks in the encoder.
+
+### 3.1 Switching to *v, w* coordinates
+
+Before working out the formulas for all this, we switch to different variables for $S_u.$ Let $v = (X/Y - u)/2$, and
+$w = 2Y.$ Or in the other direction, $X = w(u/2 + v)$ and $Y = w/2:$
+* $S_u'$ becomes the set of $(v, w)$ for which $w^2 (u^2 + uv + v^2 + a) = -g(u)$ and $w \neq 0.$
+* For $a=0$ curves, $P_u^{-1}$ can be stated for $(v,w)$ as $P_u^{'-1}(v, w) = w\left(\frac{\sqrt{-3}-1}{2}u - v\right).$
+* $\psi_u$ can be stated for $(v, w)$ as $\psi_u'(v, w) = (x_1, x_2, x_3, z)$, where
+
+$$
+\begin{array}{lcl}
+  x_1 & = & v \\
+  x_2 & = & -u - v \\
+  x_3 & = & u + w^2 \\
+  z   & = & \dfrac{g(x_3)}{w}(u^2 + uv + v^2 + a) = \dfrac{-g(u)g(x_3)}{w^3}
+\end{array}
+$$
+
+We can now write the expressions for finding $(v, w)$ given $x$ explicitly, by solving each of the $\\{x_1, x_2, x_3\\}$
+expressions for $v$ or $w$, and using the $S_u'$ equation to find the other variable:
+* Assuming $x = x_1$, we find $v = x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}$ (two solutions).
+* Assuming $x = x_2$, we find $v = -u-x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}$ (two solutions).
+* Assuming $x = x_3$, we find $w = \pm\sqrt{x-u}$ and $v = -u/2 \pm \sqrt{-w^2(4g(u) + w^2h(u))}/(2w^2)$ (four solutions).
+
+### 3.2 Avoiding computing all inverses
+
+The *ElligatorSwift* algorithm as stated in Section 1 requires the computation of $L = F_u^{-1}(x)$ (the
+set of all $t$ such that $(u, t)$ decode to $x$) in full. This is unnecessary.
+
+Observe that the procedure of restarting with probability $(1 - \frac{\\#L}{8})$ and otherwise returning a
+uniformly random element from $L$ is actually equivalent to always padding $L$ with $\bot$ values up to length 8,
+picking a uniformly random element from that, restarting whenever $\bot$ is picked:
+
+**Define** *ElligatorSwift(x)* as:
+* Loop:
+  * Pick a uniformly random field element $u.$
+  * Compute the set $L = F_u^{-1}(x).$
+  * Let $T$ be the 8-element vector consisting of the elements of $L$, plus $8 - \\#L$ times $\\{\bot\\}.$
+  * Select a uniformly random $t \in T.$
+  * If $t \neq \bot$, return $(u, t)$; restart loop otherwise.
+
+Now notice that the order of elements in $T$ does not matter, as all we do is pick a uniformly
+random element in it, so we do not need to have all $\bot$ values at the end.
+As we have 8 distinct formulas for finding $(v, w)$ (taking the variants due to $\pm$ into account),
+we can associate every index in $T$ with exactly one of those formulas, making sure that:
+* Formulas that yield no solutions (due to division by zero or non-existing square roots) or invalid solutions are made to return $\bot.$
+* For the $x_1$ and $x_2$ cases, if $g(-u-x)$ is a square, $\bot$ is returned instead (the round-trip check).
+* In case multiple formulas would return the same non- $\bot$ result, all but one of those must be turned into $\bot$ to avoid biasing those.
+
+The last condition above only occurs with negligible probability for cryptographically-sized curves, but is interesting
+to take into account as it allows exhaustive testing in small groups. See [Section 3.4](#34-dealing-with-special-cases)
+for an analysis of all the negligible cases.
+
+If we define $T = (G_{0,u}(x), G_{1,u}(x), \ldots, G_{7,u}(x))$, with each $G_{i,u}$ matching one of the formulas,
+the loop can be simplified to only compute one of the inverses instead of all of them:
+
+**Define** *ElligatorSwift(x)* as:
+* Loop:
+  * Pick a uniformly random field element $u.$
+  * Pick a uniformly random integer $c$ in $[0,8).$
+  * Let $t = G_{c,u}(x).$
+  * If $t \neq \bot$, return $(u, t)$; restart loop otherwise.
+
+This is implemented in `secp256k1_ellswift_xelligatorswift_var`.
+
+### 3.3 Finding the inverse
+
+To implement $G_{c,u}$, we map $c=0$ to the $x_1$ formula, $c=1$ to the $x_2$ formula, and $c=2$ and $c=3$ to the $x_3$ formula.
+Those are then repeated as $c=4$ through $c=7$ for the other sign of $w$ (noting that in each formula, $w$ is a square root of some expression).
+Ignoring the negligible cases, we get:
+
+**Define** $G_{c,u}(x)$ as:
+* If $c \in \\{0, 1, 4, 5\\}$ (for $x_1$ and $x_2$ formulas):
+  * If $g(-u-x)$ is square, return $\bot$ (as $x_3$ would be valid and take precedence).
+  * If $c \in \\{0, 4\\}$ (the $x_1$ formula) let $v = x$, otherwise let $v = -u-x$ (the $x_2$ formula)
+  * Let $s = -g(u)/(u^2 + uv + v^2 + a)$ (using $s = w^2$ in what follows).
+* Otherwise, when $c \in \\{2, 3, 6, 7\\}$ (for $x_3$ formulas):
+  * Let $s = x-u.$
+  * Let $r = \sqrt{-s(4g(u) + sh(u))}.$
+  * Let $v = (r/s - u)/2$ if $c \in \\{3, 7\\}$; $(-r/s - u)/2$ otherwise.
+* Let $w = \sqrt{s}.$
+* Depending on $c:$
+  * If $c \in \\{0, 1, 2, 3\\}:$ return $P_u^{'-1}(v, w).$
+  * If $c \in \\{4, 5, 6, 7\\}:$ return $P_u^{'-1}(v, -w).$
+
+Whenever a square root of a non-square is taken, $\bot$ is returned; for both square roots this happens with roughly
+50% on random inputs. Similarly, when a division by 0 would occur, $\bot$ is returned as well; this will only happen
+with negligible probability. A division by 0 in the first branch in fact cannot occur at all, because $u^2 + uv + v^2 + a = 0$
+implies $g(-u-x) = g(x)$ which would mean the $g(-u-x)$ is square condition has triggered
+and $\bot$ would have been returned already.
+
+**Note**: In the paper, the $case$ variable corresponds roughly to the $c$ above, but only takes on 4 possible values (1 to 4).
+The conditional negation of $w$ at the end is done randomly, which is equivalent, but makes testing harder. We choose to
+have the $G_{c,u}$ be deterministic, and capture all choices in $c.$
+
+Now observe that the $c \in \\{1, 5\\}$ and $c \in \\{3, 7\\}$ conditions effectively perform the same $v \rightarrow -u-v$
+transformation. Furthermore, that transformation has no effect on $s$ in the first branch
+as $u^2 + ux + x^2 + a = u^2 + u(-u-x) + (-u-x)^2 + a.$ Thus we can extract it out and move it down:
+
+**Define** $G_{c,u}(x)$ as:
+* If $c \in \\{0, 1, 4, 5\\}:$
+  * If $g(-u-x)$ is square, return $\bot.$
+  * Let $s = -g(u)/(u^2 + ux + x^2 + a).$
+  * Let $v = x.$
+* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$
+  * Let $s = x-u.$
+  * Let $r = \sqrt{-s(4g(u) + sh(u))}.$
+  * Let $v = (r/s - u)/2.$
+* Let $w = \sqrt{s}.$
+* Depending on $c:$
+  * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w).$
+  * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w).$
+  * If $c \in \\{4, 6\\}:$ return $P_u^{'-1}(v, -w).$
+  * If $c \in \\{5, 7\\}:$ return $P_u^{'-1}(-u-v, -w).$
+
+This shows there will always be exactly 0, 4, or 8 $t$ values for a given $(u, x)$ input.
+There can be 0, 1, or 2 $(v, w)$ pairs before invoking $P_u^{'-1}$, and each results in 4 distinct $t$ values.
+
+### 3.4 Dealing with special cases
+
+As mentioned before there are a few cases to deal with which only happen in a negligibly small subset of inputs.
+For cryptographically sized fields, if only random inputs are going to be considered, it is unnecessary to deal with these. Still, for completeness
+we analyse them here. They generally fall into two categories: cases in which the encoder would produce $t$ values that
+do not decode back to $x$ (or at least cannot guarantee that they do), and cases in which the encoder might produce the same
+$t$ value for multiple $c$ inputs (thereby biasing that encoding):
+
+* In the branch for $x_1$ and $x_2$ (where $c \in \\{0, 1, 4, 5\\}$):
+  * When $g(u) = 0$, we would have $s=w=Y=0$, which is not on $S_u.$ This is only possible on even-ordered curves.
+    Excluding this also removes the one condition under which the simplified check for $x_3$ on the curve
+    fails (namely when $g(x_1)=g(x_2)=0$ but $g(x_3)$ is not square).
+    This does exclude some valid encodings: when both $g(u)=0$ and $u^2+ux+x^2+a=0$ (also implying $g(x)=0$),
+    the $S_u'$ equation degenerates to $0 = 0$, and many valid $t$ values may exist. Yet, these cannot be targeted uniformly by the
+    encoder anyway as there will generally be more than 8.
+  * When $g(x) = 0$, the same $t$ would be produced as in the $x_3$ branch (where $c \in \\{2, 3, 6, 7\\}$) which we give precedence
+    as it can deal with $g(u)=0$.
+    This is again only possible on even-ordered curves.
+* In the branch for $x_3$ (where $c \in \\{2, 3, 6, 7\\}$):
+  * When $s=0$, a division by zero would occur.
+  * When $v = -u-v$ and $c \in \\{3, 7\\}$, the same $t$ would be returned as in the $c \in \\{2, 6\\}$ cases.
+    It is equivalent to checking whether $r=0$.
+    This cannot occur in the $x_1$ or $x_2$ branches, as it would trigger the $g(-u-x)$ is square condition.
+    A similar concern for $w = -w$ does not exist, as $w=0$ is already impossible in both branches: in the first
+    it requires $g(u)=0$ which is already outlawed on even-ordered curves and impossible on others; in the second it would trigger division by zero.
+* Curve-specific special cases also exist that need to be rejected, because they result in $(u,t)$ which is invalid to the decoder, or because of division by zero in the encoder:
+  * For $a=0$ curves, when $u=0$ or when $t=0$. The latter can only be reached by the encoder when $g(u)=0$, which requires an even-ordered curve.
+  * For $a \neq 0$ curves, when $X_0(u)=0$, when $h(u)t^2 = -1$, or when $w(u + 2v) = 2X_0(u)$ while also either $w \neq 2Y_0(u)$ or $h(u)=0$.
+
+**Define** a version of $G_{c,u}(x)$ which deals with all these cases:
+* If $a=0$ and $u=0$, return $\bot.$
+* If $a \neq 0$ and $X_0(u)=0$, return $\bot.$
+* If $c \in \\{0, 1, 4, 5\\}:$
+  * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only).
+  * If $g(-u-x)$ is square, return $\bot.$
+  * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero).
+  * Let $v = x.$
+* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$
+  * Let $s = x-u.$
+  * Let $r = \sqrt{-s(4g(u) + sh(u))}$; return $\bot$ if not square.
+  * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$
+  * If $s = 0$, return $\bot.$
+  * Let $v = (r/s - u)/2.$
+* Let $w = \sqrt{s}$; return $\bot$ if not square.
+* If $a \neq 0$ and $w(u+2v) = 2X_0(u)$ and either $w \neq 2Y_0(u)$ or $h(u) = 0$, return $\bot.$
+* Depending on $c:$
+  * If $c \in \\{0, 2\\}$, let $t = P_u^{'-1}(v, w).$
+  * If $c \in \\{1, 3\\}$, let $t = P_u^{'-1}(-u-v, w).$
+  * If $c \in \\{4, 6\\}$, let $t = P_u^{'-1}(v, -w).$
+  * If $c \in \\{5, 7\\}$, let $t = P_u^{'-1}(-u-v, -w).$
+* If $a=0$ and $t=0$, return $\bot$ (even curves only).
+* If $a \neq 0$ and $h(u)t^2 = -1$, return $\bot.$
+* Return $t.$
+
+Given any $u$, using this algorithm over all $x$ and $c$ values, every $t$ value will be reached exactly once,
+for an $x$ for which $F_u(t) = x$ holds, except for these cases that will not be reached:
+* All cases where $P_u(t)$ is not defined:
+  * For $a=0$ curves, when $u=0$, $t=0$, or $g(u) = -t^2.$
+  * For $a \neq 0$ curves, when $h(u)t^2 = -1$, $X_0(u) = 0$, or $Y_0(u) (1 - h(u) t^2) = 2X_0(u)t.$
+* When $g(u)=0$, the potentially many $t$ values that decode to an $x$ satisfying $g(x)=0$ using the $x_2$ formula. These were excluded by the $g(u)=0$ condition in the $c \in \\{0, 1, 4, 5\\}$ branch.
+
+These cases form a negligible subset of all $(u, t)$ for cryptographically sized curves.
+
+### 3.5 Encoding for `secp256k1`
+
+Specialized for odd-ordered $a=0$ curves:
+
+**Define** $G_{c,u}(x)$ as:
+* If $u=0$, return $\bot.$
+* If $c \in \\{0, 1, 4, 5\\}:$
+  * If $(-u-x)^3 + b$ is square, return $\bot$
+  * Let $s = -(u^3 + b)/(u^2 + ux + x^2)$ (cannot cause division by 0).
+  * Let $v = x.$
+* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$
+  * Let $s = x-u.$
+  * Let $r = \sqrt{-s(4(u^3 + b) + 3su^2)}$; return $\bot$ if not square.
+  * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$
+  * If $s = 0$, return $\bot.$
+  * Let $v = (r/s - u)/2.$
+* Let $w = \sqrt{s}$; return $\bot$ if not square.
+* Depending on $c:$
+  * If $c \in \\{0, 2\\}:$ return $w(\frac{\sqrt{-3}-1}{2}u - v).$
+  * If $c \in \\{1, 3\\}:$ return $w(\frac{\sqrt{-3}+1}{2}u + v).$
+  * If $c \in \\{4, 6\\}:$ return $w(\frac{-\sqrt{-3}+1}{2}u + v).$
+  * If $c \in \\{5, 7\\}:$ return $w(\frac{-\sqrt{-3}-1}{2}u - v).$
+
+This is implemented in `secp256k1_ellswift_xswiftec_inv_var`.
+
+And the x-only ElligatorSwift encoding algorithm is still:
+
+**Define** *ElligatorSwift(x)* as:
+* Loop:
+  * Pick a uniformly random field element $u.$
+  * Pick a uniformly random integer $c$ in $[0,8).$
+  * Let $t = G_{c,u}(x).$
+  * If $t \neq \bot$, return $(u, t)$; restart loop otherwise.
+
+Note that this logic does not take the remapped $u=0$, $t=0$, and $g(u) = -t^2$ cases into account; it just avoids them.
+While it is not impossible to make the encoder target them, this would increase the maximum number of $t$ values for a given $(u, x)$
+combination beyond 8, and thereby slow down the ElligatorSwift loop proportionally, for a negligible gain in uniformity.
+
+## 4. Encoding and decoding full *(x, y)* coordinates
+
+So far we have only addressed encoding and decoding x-coordinates, but in some cases an encoding
+for full points with $(x, y)$ coordinates is desirable. It is possible to encode this information
+in $t$ as well.
+
+Note that for any $(X, Y) \in S_u$, $(\pm X, \pm Y)$ are all on $S_u.$ Moreover, all of these are
+mapped to the same x-coordinate. Negating $X$ or negating $Y$ just results in $x_1$ and $x_2$
+being swapped, and does not affect $x_3.$ This will not change the outcome x-coordinate as the order
+of $x_1$ and $x_2$ only matters if both were to be valid, and in that case $x_3$ would be used instead.
+
+Still, these four $(X, Y)$ combinations all correspond to distinct $t$ values, so we can encode
+the sign of the y-coordinate in the sign of $X$ or the sign of $Y.$ They correspond to the
+four distinct $P_u^{'-1}$ calls in the definition of $G_{u,c}.$
+
+**Note**: In the paper, the sign of the y coordinate is encoded in a separately-coded bit.
+
+To encode the sign of $y$ in the sign of $Y:$
+
+**Define** *Decode(u, t)* for full $(x, y)$ as:
+* Let $(X, Y) = P_u(t).$
+* Let $x$ be the first value in $(u + 4Y^2, \frac{-X}{2Y} - \frac{u}{2}, \frac{X}{2Y} - \frac{u}{2})$ for which $g(x)$ is square.
+* Let $y = \sqrt{g(x)}.$
+* If $sign(y) = sign(Y)$, return $(x, y)$; otherwise return $(x, -y).$
+
+And encoding would be done using a $G_{c,u}(x, y)$ function defined as:
+
+**Define** $G_{c,u}(x, y)$ as:
+* If $c \in \\{0, 1\\}:$
+  * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only).
+  * If $g(-u-x)$ is square, return $\bot.$
+  * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero).
+  * Let $v = x.$
+* Otherwise, when $c \in \\{2, 3\\}:$
+  * Let $s = x-u.$
+  * Let $r = \sqrt{-s(4g(u) + sh(u))}$; return $\bot$ if not square.
+  * If $c = 3$ and $r = 0$, return $\bot.$
+  * Let $v = (r/s - u)/2.$
+* Let $w = \sqrt{s}$; return $\bot$ if not square.
+* Let $w' = w$ if $sign(w/2) = sign(y)$; $-w$ otherwise.
+* Depending on $c:$
+  * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w').$
+  * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w').$
+
+Note that $c$ now only ranges $[0,4)$, as the sign of $w'$ is decided based on that of $y$, rather than on $c.$
+This change makes some valid encodings unreachable: when $y = 0$ and $sign(Y) \neq sign(0)$.
+
+In the above logic, $sign$ can be implemented in several ways, such as parity of the integer representation
+of the input field element (for prime-sized fields) or the quadratic residuosity (for fields where
+$-1$ is not square). The choice does not matter, as long as it only takes on two possible values, and for $x \neq 0$ it holds that $sign(x) \neq sign(-x)$.
+
+### 4.1 Full *(x, y)* coordinates for `secp256k1`
+
+For $a=0$ curves, there is another option. Note that for those,
+the $P_u(t)$ function translates negations of $t$ to negations of (both) $X$ and $Y.$ Thus, we can use $sign(t)$ to
+encode the y-coordinate directly. Combined with the earlier remapping to guarantee all inputs land on the curve, we get
+as decoder:
+
+**Define** *Decode(u, t)* as:
+* Let $u'=u$ if $u \neq 0$; $1$ otherwise.
+* Let $t'=t$ if $t \neq 0$; $1$ otherwise.
+* Let $t''=t'$ if $u'^3 + b + t'^2 \neq 0$; $2t'$ otherwise.
+* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$
+* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$
+* Let $x$ be the first element of $(u' + 4Y^2, \frac{-X}{2Y} - \frac{u'}{2}, \frac{X}{2Y} - \frac{u'}{2})$ for which $g(x)$ is square.
+* Let $y = \sqrt{g(x)}.$
+* Return $(x, y)$ if $sign(y) = sign(t)$; $(x, -y)$ otherwise.
+
+This is implemented in `secp256k1_ellswift_swiftec_var`. The used $sign(x)$ function is the parity of $x$ when represented as in integer in $[0,q).$
+
+The corresponding encoder would invoke the x-only one, but negating the output $t$ if $sign(t) \neq sign(y).$
+
+This is implemented in `secp256k1_ellswift_elligatorswift_var`.
+
+Note that this is only intended for encoding points where both the x-coordinate and y-coordinate are unpredictable. When encoding x-only points
+where the y-coordinate is implicitly even (or implicitly square, or implicitly in $[0,q/2]$), the encoder in
+[Section 3.5](#35-encoding-for-secp256k1) must be used, or a bias is reintroduced that undoes all the benefit of using ElligatorSwift
+in the first place.

doc/release-process.md

@@ -12,33 +12,74 @@ It is best if the maintainers are present during the release, so they can help e
 
 This process also assumes that there will be no minor releases for old major releases.
 
+We aim to cut a regular release every 3-4 months, approximately twice as frequent as major Bitcoin Core releases. Every second release should be published one month before the feature freeze of the next major Bitcoin Core release, allowing sufficient time to update the library in Core.
+
+## Sanity Checks
+Perform these checks before creating a release:
+
+1. Ensure `make distcheck` doesn't fail.
+```shell
+./autogen.sh && ./configure --enable-dev-mode && make distcheck
+```
+2. Check installation with autotools:
+```shell
+dir=$(mktemp -d)
+./autogen.sh && ./configure --prefix=$dir && make clean && make install && ls -RlAh $dir
+gcc -o ecdsa examples/ecdsa.c $(PKG_CONFIG_PATH=$dir/lib/pkgconfig pkg-config --cflags --libs libsecp256k1) -Wl,-rpath,"$dir/lib" && ./ecdsa
+```
+3. Check installation with CMake:
+```shell
+dir=$(mktemp -d)
+build=$(mktemp -d)
+cmake -B $build -DCMAKE_INSTALL_PREFIX=$dir && cmake --build $build --target install && ls -RlAh $dir
+gcc -o ecdsa examples/ecdsa.c -I $dir/include -L $dir/lib*/ -l secp256k1 -Wl,-rpath,"$dir/lib",-rpath,"$dir/lib64" && ./ecdsa
+```
+4. Use the [`check-abi.sh`](/tools/check-abi.sh) tool to ensure there are no unexpected ABI incompatibilities and that the version number and release notes accurately reflect all potential ABI changes. To run this tool, the `abi-dumper` and `abi-compliance-checker` packages are required.
+
+```shell
+tools/check-abi.sh
+```
+
 ## Regular release
 
 1. Open a PR to the master branch with a commit (using message `"release: prepare for $MAJOR.$MINOR.$PATCH"`, for example) that
-   * finalizes the release notes in [CHANGELOG.md](../CHANGELOG.md) (make sure to include an entry for `### ABI Compatibility`) and
-   * updates `_PKG_VERSION_*`, `_LIB_VERSION_*`, and sets `_PKG_VERSION_IS_RELEASE` to `true` in `configure.ac`.
+   * finalizes the release notes in [CHANGELOG.md](../CHANGELOG.md) by
+       * adding a section for the release (make sure that the version number is a link to a diff between the previous and new version),
+       * removing the `[Unreleased]` section header, and
+       * including an entry for `### ABI Compatibility` if it doesn't exist,
+   * sets `_PKG_VERSION_IS_RELEASE` to `true` in `configure.ac`, and
+   * if this is not a patch release
+       * updates `_PKG_VERSION_*` and `_LIB_VERSION_*`  in `configure.ac` and
+       * updates `project(libsecp256k1 VERSION ...)` and `${PROJECT_NAME}_LIB_VERSION_*` in `CMakeLists.txt`.
 2. After the PR is merged, tag the commit and push it:
    ```
    RELEASE_COMMIT=<merge commit of step 1>
    git tag -s v$MAJOR.$MINOR.$PATCH -m "libsecp256k1 $MAJOR.$MINOR.$PATCH" $RELEASE_COMMIT
    git push git@github.com:bitcoin-core/secp256k1.git v$MAJOR.$MINOR.$PATCH
    ```
-3. Open a PR to the master branch with a commit (using message `"release: bump version after $MAJOR.$MINOR.$PATCH"`, for example) that sets `_PKG_VERSION_IS_RELEASE` to `false` and `_PKG_VERSION_PATCH` to `$PATCH + 1` and increases `_LIB_VERSION_REVISION`. If other maintainers are not present to approve the PR, it can be merged without ACKs.
+3. Open a PR to the master branch with a commit (using message `"release cleanup: bump version after $MAJOR.$MINOR.$PATCH"`, for example) that
+   * sets `_PKG_VERSION_IS_RELEASE` to `false` and increments `_PKG_VERSION_PATCH` and `_LIB_VERSION_REVISION` in `configure.ac`,
+   * increments the `$PATCH` component of `project(libsecp256k1 VERSION ...)` and `${PROJECT_NAME}_LIB_VERSION_REVISION` in `CMakeLists.txt`, and
+   * adds an `[Unreleased]` section header to the [CHANGELOG.md](../CHANGELOG.md).
+
+   If other maintainers are not present to approve the PR, it can be merged without ACKs.
 4. Create a new GitHub release with a link to the corresponding entry in [CHANGELOG.md](../CHANGELOG.md).
 
 ## Maintenance release
 
 Note that bugfixes only need to be backported to releases for which no compatible release without the bug exists.
 
-1. If `$PATCH = 1`, create maintenance branch `$MAJOR.$MINOR`:
+1. If there's no maintenance branch `$MAJOR.$MINOR`, create one:
    ```
-   git checkout -b $MAJOR.$MINOR v$MAJOR.$MINOR.0
+   git checkout -b $MAJOR.$MINOR v$MAJOR.$MINOR.$((PATCH - 1))
    git push git@github.com:bitcoin-core/secp256k1.git $MAJOR.$MINOR
    ```
 2. Open a pull request to the `$MAJOR.$MINOR` branch that
    * includes the bugfixes,
-   * finalizes the release notes,
-   * bumps `_PKG_VERSION_PATCH` and `_LIB_VERSION_REVISION` in `configure.ac` (with commit message `"release: update PKG_ and LIB_VERSION for $MAJOR.$MINOR.$PATCH"`, for example).
+   * finalizes the release notes similar to a regular release,
+   * increments `_PKG_VERSION_PATCH` and `_LIB_VERSION_REVISION` in `configure.ac`
+     and the `$PATCH` component of `project(libsecp256k1 VERSION ...)` and `${PROJECT_NAME}_LIB_VERSION_REVISION` in `CMakeLists.txt`
+     (with commit message `"release: bump versions for $MAJOR.$MINOR.$PATCH"`, for example).
 3. After the PRs are merged, update the release branch and tag the commit:
    ```
    git checkout $MAJOR.$MINOR && git pull

doc/safegcd_implementation.md

@@ -1,7 +1,7 @@
 # The safegcd implementation in libsecp256k1 explained
 
-This document explains the modular inverse implementation in the `src/modinv*.h` files. It is based
-on the paper
+This document explains the modular inverse and Jacobi symbol implementations in the `src/modinv*.h` files.
+It is based on the paper
 ["Fast constant-time gcd computation and modular inversion"](https://gcd.cr.yp.to/papers.html#safegcd)
 by Daniel J. Bernstein and Bo-Yin Yang. The references below are for the Date: 2019.04.13 version.
 
@@ -410,7 +410,7 @@ sufficient even. Given that every loop iteration performs *N* divsteps, it will
 
 To deal with the branches in `divsteps_n_matrix` we will replace them with constant-time bitwise
 operations (and hope the C compiler isn't smart enough to turn them back into branches; see
-`valgrind_ctime_test.c` for automated tests that this isn't the case). To do so, observe that a
+`ctime_tests.c` for automated tests that this isn't the case). To do so, observe that a
 divstep can be written instead as (compare to the inner loop of `gcd` in section 1).
 
 ```python
@@ -769,3 +769,51 @@ def modinv_var(M, Mi, x):
         d, e = update_de(d, e, t, M, Mi)
     return normalize(f, d, Mi)
 ```
+
+## 8. From GCDs to Jacobi symbol
+
+We can also use a similar approach to calculate Jacobi symbol *(x | M)* by keeping track of an
+extra variable *j*, for which at every step *(x | M) = j (g | f)*. As we update *f* and *g*, we
+make corresponding updates to *j* using
+[properties of the Jacobi symbol](https://en.wikipedia.org/wiki/Jacobi_symbol#Properties):
+* *((g/2) | f)* is either *(g | f)* or *-(g | f)*, depending on the value of *f mod 8* (negating if it's *3* or *5*).
+* *(f | g)* is either *(g | f)* or *-(g | f)*, depending on *f mod 4* and *g mod 4* (negating if both are *3*).
+
+These updates depend only on the values of *f* and *g* modulo *4* or *8*, and can thus be applied
+very quickly, as long as we keep track of a few additional bits of *f* and *g*. Overall, this
+calculation is slightly simpler than the one for the modular inverse because we no longer need to
+keep track of *d* and *e*.
+
+However, one difficulty of this approach is that the Jacobi symbol *(a | n)* is only defined for
+positive odd integers *n*, whereas in the original safegcd algorithm, *f, g* can take negative
+values. We resolve this by using the following modified steps:
+
+```python
+        # Before
+        if delta > 0 and g & 1:
+            delta, f, g = 1 - delta, g, (g - f) // 2
+
+        # After
+        if delta > 0 and g & 1:
+            delta, f, g = 1 - delta, g, (g + f) // 2
+```
+
+The algorithm is still correct, since the changed divstep, called a "posdivstep" (see section 8.4
+and E.5 in the paper) preserves *gcd(f, g)*. However, there's no proof that the modified algorithm
+will converge. The justification for posdivsteps is completely empirical: in practice, it appears
+that the vast majority of nonzero inputs converge to *f=g=gcd(f<sub>0</sub>, g<sub>0</sub>)* in a
+number of steps proportional to their logarithm.
+
+Note that:
+- We require inputs to satisfy *gcd(x, M) = 1*, as otherwise *f=1* is not reached.
+- We require inputs *x &neq; 0*, because applying posdivstep with *g=0* has no effect.
+- We need to update the termination condition from *g=0* to *f=1*.
+
+We account for the possibility of nonconvergence by only performing a bounded number of
+posdivsteps, and then falling back to square-root based Jacobi calculation if a solution has not
+yet been found.
+
+The optimizations in sections 3-7 above are described in the context of the original divsteps, but
+in the C implementation we also adapt most of them (not including "avoiding modulus operations",
+since it's not necessary to track *d, e*, and "constant-time operation", since we never calculate
+Jacobi symbols for secret data) to the posdivsteps version.

examples/CMakeLists.txt

@@ -0,0 +1,30 @@
+function(add_example name)
+  set(target_name ${name}_example)
+  add_executable(${target_name} ${name}.c)
+  target_include_directories(${target_name} PRIVATE
+    ${PROJECT_SOURCE_DIR}/include
+  )
+  target_link_libraries(${target_name}
+    secp256k1
+    $<$<PLATFORM_ID:Windows>:bcrypt>
+  )
+  set(test_name ${name}_example)
+  add_test(NAME ${test_name} COMMAND ${target_name})
+  if(BUILD_SHARED_LIBS AND MSVC)
+    # The DLL must reside either in the same folder where the executable is
+    # or somewhere in PATH. Using the latter option.
+    set_tests_properties(${test_name} PROPERTIES
+      ENVIRONMENT "PATH=$<TARGET_FILE_DIR:secp256k1>;$ENV{PATH}"
+    )
+  endif()
+endfunction()
+
+add_example(ecdsa)
+
+if(SECP256K1_ENABLE_MODULE_ECDH)
+  add_example(ecdh)
+endif()
+
+if(SECP256K1_ENABLE_MODULE_SCHNORRSIG)
+  add_example(schnorr)
+endif()

examples/ecdh.c

@@ -14,8 +14,7 @@
 #include <secp256k1.h>
 #include <secp256k1_ecdh.h>
 
-#include "random.h"
-
+#include "examples_util.h"
 
 int main(void) {
     unsigned char seckey1[32];
@@ -112,12 +111,12 @@ int main(void) {
      * example through "out of bounds" array access (see Heartbleed), Or the OS
      * swapping them to disk. Hence, we overwrite the secret key buffer with zeros.
      *
-     * TODO: Prevent these writes from being optimized out, as any good compiler
+     * Here we are preventing these writes from being optimized out, as any good compiler
      * will remove any writes that aren't used. */
-    memset(seckey1, 0, sizeof(seckey1));
-    memset(seckey2, 0, sizeof(seckey2));
-    memset(shared_secret1, 0, sizeof(shared_secret1));
-    memset(shared_secret2, 0, sizeof(shared_secret2));
+    secure_erase(seckey1, sizeof(seckey1));
+    secure_erase(seckey2, sizeof(seckey2));
+    secure_erase(shared_secret1, sizeof(shared_secret1));
+    secure_erase(shared_secret2, sizeof(shared_secret2));
 
     return 0;
 }

examples/ecdsa.c

@@ -13,9 +13,7 @@
 
 #include <secp256k1.h>
 
-#include "random.h"
-
-
+#include "examples_util.h"
 
 int main(void) {
     /* Instead of signing the message directly, we must sign a 32-byte hash.
@@ -34,7 +32,7 @@ int main(void) {
     unsigned char compressed_pubkey[33];
     unsigned char serialized_signature[64];
     size_t len;
-    int is_signature_valid;
+    int is_signature_valid, is_signature_valid2;
     int return_val;
     secp256k1_pubkey pubkey;
     secp256k1_ecdsa_signature sig;
@@ -116,18 +114,26 @@ int main(void) {
     printf("Signature: ");
     print_hex(serialized_signature, sizeof(serialized_signature));
 
-
     /* This will clear everything from the context and free the memory */
     secp256k1_context_destroy(ctx);
 
+    /* Bonus example: if all we need is signature verification (and no key
+       generation or signing), we don't need to use a context created via
+       secp256k1_context_create(). We can simply use the static (i.e., global)
+       context secp256k1_context_static. See its description in
+       include/secp256k1.h for details. */
+    is_signature_valid2 = secp256k1_ecdsa_verify(secp256k1_context_static,
+                                                 &sig, msg_hash, &pubkey);
+    assert(is_signature_valid2 == is_signature_valid);
+
     /* It's best practice to try to clear secrets from memory after using them.
      * This is done because some bugs can allow an attacker to leak memory, for
      * example through "out of bounds" array access (see Heartbleed), Or the OS
      * swapping them to disk. Hence, we overwrite the secret key buffer with zeros.
      *
-     * TODO: Prevent these writes from being optimized out, as any good compiler
+     * Here we are preventing these writes from being optimized out, as any good compiler
      * will remove any writes that aren't used. */
-    memset(seckey, 0, sizeof(seckey));
+    secure_erase(seckey, sizeof(seckey));
 
     return 0;
 }

examples/examples_util.h

@@ -17,7 +17,13 @@
  */
 
 #if defined(_WIN32)
+/*
+ * The defined WIN32_NO_STATUS macro disables return code definitions in
+ * windows.h, which avoids "macro redefinition" MSVC warnings in ntstatus.h.
+ */
+#define WIN32_NO_STATUS
 #include <windows.h>
+#undef WIN32_NO_STATUS
 #include <ntstatus.h>
 #include <bcrypt.h>
 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__)
@@ -71,3 +77,32 @@ static void print_hex(unsigned char* data, size_t size) {
     }
     printf("\n");
 }
+
+#if defined(_MSC_VER)
+// For SecureZeroMemory
+#include <Windows.h>
+#endif
+/* Cleanses memory to prevent leaking sensitive info. Won't be optimized out. */
+static void secure_erase(void *ptr, size_t len) {
+#if defined(_MSC_VER)
+    /* SecureZeroMemory is guaranteed not to be optimized out by MSVC. */
+    SecureZeroMemory(ptr, len);
+#elif defined(__GNUC__)
+    /* We use a memory barrier that scares the compiler away from optimizing out the memset.
+     *
+     * Quoting Adam Langley <agl@google.com> in commit ad1907fe73334d6c696c8539646c21b11178f20f
+     * in BoringSSL (ISC License):
+     *    As best as we can tell, this is sufficient to break any optimisations that
+     *    might try to eliminate "superfluous" memsets.
+     * This method used in memzero_explicit() the Linux kernel, too. Its advantage is that it is
+     * pretty efficient, because the compiler can still implement the memset() efficiently,
+     * just not remove it entirely. See "Dead Store Elimination (Still) Considered Harmful" by
+     * Yang et al. (USENIX Security 2017) for more background.
+     */
+    memset(ptr, 0, len);
+    __asm__ __volatile__("" : : "r"(ptr) : "memory");
+#else
+    void *(*volatile const volatile_memset)(void *, int, size_t) = memset;
+    volatile_memset(ptr, 0, len);
+#endif
+}

examples/schnorr.c

@@ -15,7 +15,7 @@
 #include <secp256k1_extrakeys.h>
 #include <secp256k1_schnorrsig.h>
 
-#include "random.h"
+#include "examples_util.h"
 
 int main(void) {
     unsigned char msg[12] = "Hello World!";
@@ -26,7 +26,7 @@ int main(void) {
     unsigned char auxiliary_rand[32];
     unsigned char serialized_pubkey[32];
     unsigned char signature[64];
-    int is_signature_valid;
+    int is_signature_valid, is_signature_valid2;
     int return_val;
     secp256k1_xonly_pubkey pubkey;
     secp256k1_keypair keypair;
@@ -135,14 +135,22 @@ int main(void) {
     /* This will clear everything from the context and free the memory */
     secp256k1_context_destroy(ctx);
 
+    /* Bonus example: if all we need is signature verification (and no key
+       generation or signing), we don't need to use a context created via
+       secp256k1_context_create(). We can simply use the static (i.e., global)
+       context secp256k1_context_static. See its description in
+       include/secp256k1.h for details. */
+    is_signature_valid2 = secp256k1_schnorrsig_verify(secp256k1_context_static,
+                                                      signature, msg_hash, 32, &pubkey);
+    assert(is_signature_valid2 == is_signature_valid);
+
     /* It's best practice to try to clear secrets from memory after using them.
      * This is done because some bugs can allow an attacker to leak memory, for
      * example through "out of bounds" array access (see Heartbleed), Or the OS
      * swapping them to disk. Hence, we overwrite the secret key buffer with zeros.
      *
-     * TODO: Prevent these writes from being optimized out, as any good compiler
+     * Here we are preventing these writes from being optimized out, as any good compiler
      * will remove any writes that aren't used. */
-    memset(seckey, 0, sizeof(seckey));
-
+    secure_erase(seckey, sizeof(seckey));
     return 0;
 }

include/secp256k1.h

@@ -122,18 +122,6 @@ typedef int (*secp256k1_nonce_function)(
 #  endif
 # endif
 
-# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
-#  if SECP256K1_GNUC_PREREQ(2,7)
-#   define SECP256K1_INLINE __inline__
-#  elif (defined(_MSC_VER))
-#   define SECP256K1_INLINE __inline
-#  else
-#   define SECP256K1_INLINE
-#  endif
-# else
-#  define SECP256K1_INLINE inline
-# endif
-
 /*  When this header is used at build-time the SECP256K1_BUILD define needs to be set
  *  to correctly setup export attributes and nullness checks.  This is normally done
  *  by secp256k1.c but to guard against this header being included before secp256k1.c
@@ -145,21 +133,35 @@ typedef int (*secp256k1_nonce_function)(
 # define SECP256K1_NO_BUILD
 #endif
 
-/** At secp256k1 build-time DLL_EXPORT is defined when building objects destined
- *  for a shared library, but not for those intended for static libraries.
- */
-
-#ifndef SECP256K1_API
-# if defined(_WIN32)
-#  if defined(SECP256K1_BUILD) && defined(DLL_EXPORT)
-#   define SECP256K1_API __declspec(dllexport)
-#  else
-#   define SECP256K1_API
+/* Symbol visibility. */
+#if defined(_WIN32)
+  /* GCC for Windows (e.g., MinGW) accepts the __declspec syntax
+   * for MSVC compatibility. A __declspec declaration implies (but is not
+   * exactly equivalent to) __attribute__ ((visibility("default"))), and so we
+   * actually want __declspec even on GCC, see "Microsoft Windows Function
+   * Attributes" in the GCC manual and the recommendations in
+   * https://gcc.gnu.org/wiki/Visibility. */
+# if defined(SECP256K1_BUILD)
+#  if defined(DLL_EXPORT) || defined(SECP256K1_DLL_EXPORT)
+    /* Building libsecp256k1 as a DLL.
+     * 1. If using Libtool, it defines DLL_EXPORT automatically.
+     * 2. In other cases, SECP256K1_DLL_EXPORT must be defined. */
+#   define SECP256K1_API extern __declspec (dllexport)
 #  endif
-# elif defined(__GNUC__) && (__GNUC__ >= 4) && defined(SECP256K1_BUILD)
-#  define SECP256K1_API __attribute__ ((visibility ("default")))
+  /* The user must define SECP256K1_STATIC when consuming libsecp256k1 as a static
+   * library on Windows. */
+# elif !defined(SECP256K1_STATIC)
+   /* Consuming libsecp256k1 as a DLL. */
+#  define SECP256K1_API extern __declspec (dllimport)
+# endif
+#endif
+#ifndef SECP256K1_API
+# if defined(__GNUC__) && (__GNUC__ >= 4) && defined(SECP256K1_BUILD)
+   /* Building libsecp256k1 on non-Windows using GCC or compatible. */
+#  define SECP256K1_API extern __attribute__ ((visibility ("default")))
 # else
-#  define SECP256K1_API
+   /* All cases not captured above. */
+#  define SECP256K1_API extern
 # endif
 #endif
 
@@ -231,10 +233,10 @@ typedef int (*secp256k1_nonce_function)(
  *
  *  It is highly recommended to call secp256k1_selftest before using this context.
  */
-SECP256K1_API extern const secp256k1_context *secp256k1_context_static;
+SECP256K1_API const secp256k1_context *secp256k1_context_static;
 
 /** Deprecated alias for secp256k1_context_static. */
-SECP256K1_API extern const secp256k1_context *secp256k1_context_no_precomp
+SECP256K1_API const secp256k1_context *secp256k1_context_no_precomp
 SECP256K1_DEPRECATED("Use secp256k1_context_static instead");
 
 /** Perform basic self tests (to be used in conjunction with secp256k1_context_static)
@@ -281,7 +283,7 @@ SECP256K1_API void secp256k1_selftest(void);
  *  Do not create a new context object for each operation, as construction and
  *  randomization can take non-negligible time.
  */
-SECP256K1_API secp256k1_context* secp256k1_context_create(
+SECP256K1_API secp256k1_context *secp256k1_context_create(
     unsigned int flags
 ) SECP256K1_WARN_UNUSED_RESULT;
 
@@ -291,11 +293,14 @@ SECP256K1_API secp256k1_context* secp256k1_context_create(
  *  called at most once for every call of this function. If you need to avoid dynamic
  *  memory allocation entirely, see the functions in secp256k1_preallocated.h.
  *
+ *  Cloning secp256k1_context_static is not possible, and should not be emulated by
+ *  the caller (e.g., using memcpy). Create a new context instead.
+ *
  *  Returns: a newly created context object.
- *  Args:    ctx: an existing context to copy
+ *  Args:    ctx: an existing context to copy (not secp256k1_context_static)
  */
-SECP256K1_API secp256k1_context* secp256k1_context_clone(
-    const secp256k1_context* ctx
+SECP256K1_API secp256k1_context *secp256k1_context_clone(
+    const secp256k1_context *ctx
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
 
 /** Destroy a secp256k1 context object (created in dynamically allocated memory).
@@ -310,9 +315,10 @@ SECP256K1_API secp256k1_context* secp256k1_context_clone(
  *
  *  Args:   ctx: an existing context to destroy, constructed using
  *               secp256k1_context_create or secp256k1_context_clone
+ *               (i.e., not secp256k1_context_static).
  */
 SECP256K1_API void secp256k1_context_destroy(
-    secp256k1_context* ctx
+    secp256k1_context *ctx
 ) SECP256K1_ARG_NONNULL(1);
 
 /** Set a callback function to be called when an illegal argument is passed to
@@ -336,8 +342,8 @@ SECP256K1_API void secp256k1_context_destroy(
  *  USE_EXTERNAL_DEFAULT_CALLBACKS is defined, which is the case if the build
  *  has been configured with --enable-external-default-callbacks. Then the
  *  following two symbols must be provided to link against:
- *   - void secp256k1_default_illegal_callback_fn(const char* message, void* data);
- *   - void secp256k1_default_error_callback_fn(const char* message, void* data);
+ *   - void secp256k1_default_illegal_callback_fn(const char *message, void *data);
+ *   - void secp256k1_default_error_callback_fn(const char *message, void *data);
  *  The library can call these default handlers even before a proper callback data
  *  pointer could have been set using secp256k1_context_set_illegal_callback or
  *  secp256k1_context_set_error_callback, e.g., when the creation of a context
@@ -353,9 +359,9 @@ SECP256K1_API void secp256k1_context_destroy(
  *  See also secp256k1_context_set_error_callback.
  */
 SECP256K1_API void secp256k1_context_set_illegal_callback(
-    secp256k1_context* ctx,
-    void (*fun)(const char* message, void* data),
-    const void* data
+    secp256k1_context *ctx,
+    void (*fun)(const char *message, void *data),
+    const void *data
 ) SECP256K1_ARG_NONNULL(1);
 
 /** Set a callback function to be called when an internal consistency check
@@ -381,9 +387,9 @@ SECP256K1_API void secp256k1_context_set_illegal_callback(
  *  See also secp256k1_context_set_illegal_callback.
  */
 SECP256K1_API void secp256k1_context_set_error_callback(
-    secp256k1_context* ctx,
-    void (*fun)(const char* message, void* data),
-    const void* data
+    secp256k1_context *ctx,
+    void (*fun)(const char *message, void *data),
+    const void *data
 ) SECP256K1_ARG_NONNULL(1);
 
 /** Create a secp256k1 scratch space object.
@@ -393,8 +399,8 @@ SECP256K1_API void secp256k1_context_set_error_callback(
  *  In:   size: amount of memory to be available as scratch space. Some extra
  *              (<100 bytes) will be allocated for extra accounting.
  */
-SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space* secp256k1_scratch_space_create(
-    const secp256k1_context* ctx,
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space *secp256k1_scratch_space_create(
+    const secp256k1_context *ctx,
     size_t size
 ) SECP256K1_ARG_NONNULL(1);
 
@@ -405,8 +411,8 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space* secp256k1_sc
  *          scratch: space to destroy
  */
 SECP256K1_API void secp256k1_scratch_space_destroy(
-    const secp256k1_context* ctx,
-    secp256k1_scratch_space* scratch
+    const secp256k1_context *ctx,
+    secp256k1_scratch_space *scratch
 ) SECP256K1_ARG_NONNULL(1);
 
 /** Parse a variable-length public key into the pubkey object.
@@ -424,8 +430,8 @@ SECP256K1_API void secp256k1_scratch_space_destroy(
  *  byte 0x06 or 0x07) format public keys.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse(
-    const secp256k1_context* ctx,
-    secp256k1_pubkey* pubkey,
+    const secp256k1_context *ctx,
+    secp256k1_pubkey *pubkey,
     const unsigned char *input,
     size_t inputlen
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -446,10 +452,10 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse(
  *                      compressed format, otherwise SECP256K1_EC_UNCOMPRESSED.
  */
 SECP256K1_API int secp256k1_ec_pubkey_serialize(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *output,
     size_t *outputlen,
-    const secp256k1_pubkey* pubkey,
+    const secp256k1_pubkey *pubkey,
     unsigned int flags
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
@@ -463,9 +469,9 @@ SECP256K1_API int secp256k1_ec_pubkey_serialize(
  *        pubkey2:  second public key to compare
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_cmp(
-    const secp256k1_context* ctx,
-    const secp256k1_pubkey* pubkey1,
-    const secp256k1_pubkey* pubkey2
+    const secp256k1_context *ctx,
+    const secp256k1_pubkey *pubkey1,
+    const secp256k1_pubkey *pubkey2
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Parse an ECDSA signature in compact (64 bytes) format.
@@ -484,8 +490,8 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_cmp(
  *  any message and public key.
  */
 SECP256K1_API int secp256k1_ecdsa_signature_parse_compact(
-    const secp256k1_context* ctx,
-    secp256k1_ecdsa_signature* sig,
+    const secp256k1_context *ctx,
+    secp256k1_ecdsa_signature *sig,
     const unsigned char *input64
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
@@ -505,8 +511,8 @@ SECP256K1_API int secp256k1_ecdsa_signature_parse_compact(
  *  guaranteed to fail for every message and public key.
  */
 SECP256K1_API int secp256k1_ecdsa_signature_parse_der(
-    const secp256k1_context* ctx,
-    secp256k1_ecdsa_signature* sig,
+    const secp256k1_context *ctx,
+    secp256k1_ecdsa_signature *sig,
     const unsigned char *input,
     size_t inputlen
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -523,10 +529,10 @@ SECP256K1_API int secp256k1_ecdsa_signature_parse_der(
  *  In:     sig:       a pointer to an initialized signature object
  */
 SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *output,
     size_t *outputlen,
-    const secp256k1_ecdsa_signature* sig
+    const secp256k1_ecdsa_signature *sig
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Serialize an ECDSA signature in compact (64 byte) format.
@@ -539,9 +545,9 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
  *  See secp256k1_ecdsa_signature_parse_compact for details about the encoding.
  */
 SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *output64,
-    const secp256k1_ecdsa_signature* sig
+    const secp256k1_ecdsa_signature *sig
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Verify an ECDSA signature.
@@ -570,7 +576,7 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
  * For details, see the comments for that function.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     const secp256k1_ecdsa_signature *sig,
     const unsigned char *msghash32,
     const secp256k1_pubkey *pubkey
@@ -618,7 +624,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
  *  secp256k1_ecdsa_signature_normalize must be called before verification.
  */
 SECP256K1_API int secp256k1_ecdsa_signature_normalize(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_ecdsa_signature *sigout,
     const secp256k1_ecdsa_signature *sigin
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
@@ -627,10 +633,10 @@ SECP256K1_API int secp256k1_ecdsa_signature_normalize(
  * If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
  * extra entropy.
  */
-SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
+SECP256K1_API const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
 
 /** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
-SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_default;
+SECP256K1_API const secp256k1_nonce_function secp256k1_nonce_function_default;
 
 /** Create an ECDSA signature.
  *
@@ -651,7 +657,7 @@ SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_def
  * secp256k1_ecdsa_signature_normalize for more details.
  */
 SECP256K1_API int secp256k1_ecdsa_sign(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_ecdsa_signature *sig,
     const unsigned char *msghash32,
     const unsigned char *seckey,
@@ -672,7 +678,7 @@ SECP256K1_API int secp256k1_ecdsa_sign(
  *  In:      seckey: pointer to a 32-byte secret key.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     const unsigned char *seckey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
 
@@ -685,7 +691,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(
  *  In:      seckey: pointer to a 32-byte secret key.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey,
     const unsigned char *seckey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -701,14 +707,14 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
  *                  seckey will be set to some unspecified value.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_negate(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
 
 /** Same as secp256k1_ec_seckey_negate, but DEPRECATED. Will be removed in
  *  future versions. */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_negate(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2)
   SECP256K1_DEPRECATED("Use secp256k1_ec_seckey_negate instead");
@@ -720,7 +726,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_negate(
  *  In/Out: pubkey:     pointer to the public key to be negated.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
 
@@ -734,13 +740,13 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
  *                  invalid according to secp256k1_ec_seckey_verify, this
  *                  function returns 0. seckey will be set to some unspecified
  *                  value if this function returns 0.
- *  In:    tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
- *                  secp256k1_ec_seckey_verify, this function returns 0. For
- *                  uniformly random 32-byte arrays the chance of being invalid
- *                  is negligible (around 1 in 2^128).
+ *  In:    tweak32: pointer to a 32-byte tweak, which must be valid according to
+ *                  secp256k1_ec_seckey_verify or 32 zero bytes. For uniformly
+ *                  random 32-byte tweaks, the chance of being invalid is
+ *                  negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_add(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -748,7 +754,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_add(
 /** Same as secp256k1_ec_seckey_tweak_add, but DEPRECATED. Will be removed in
  *  future versions. */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3)
@@ -762,13 +768,13 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
  *  Args:    ctx:   pointer to a context object.
  *  In/Out: pubkey: pointer to a public key object. pubkey will be set to an
  *                  invalid value if this function returns 0.
- *  In:    tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
- *                  secp256k1_ec_seckey_verify, this function returns 0. For
- *                  uniformly random 32-byte arrays the chance of being invalid
- *                  is negligible (around 1 in 2^128).
+ *  In:    tweak32: pointer to a 32-byte tweak, which must be valid according to
+ *                  secp256k1_ec_seckey_verify or 32 zero bytes. For uniformly
+ *                  random 32-byte tweaks, the chance of being invalid is
+ *                  negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -787,7 +793,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
  *                  is negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_mul(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -795,7 +801,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_mul(
 /** Same as secp256k1_ec_seckey_tweak_mul, but DEPRECATED. Will be removed in
  *  future versions. */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3)
@@ -813,17 +819,17 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
  *                  is negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Randomizes the context to provide enhanced protection against side-channel leakage.
  *
- *  Returns: 1: randomization successful (or called on copy of secp256k1_context_static)
+ *  Returns: 1: randomization successful
  *           0: error
- *  Args:    ctx:       pointer to a context object.
- *  In:      seed32:    pointer to a 32-byte random seed (NULL resets to initial state)
+ *  Args:    ctx:       pointer to a context object (not secp256k1_context_static).
+ *  In:      seed32:    pointer to a 32-byte random seed (NULL resets to initial state).
  *
  * While secp256k1 code is written and tested to be constant-time no matter what
  * secret values are, it is possible that a compiler may output code which is not,
@@ -838,24 +844,20 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
  * functions that perform computations involving secret keys, e.g., signing and
  * public key generation. It is possible to call this function more than once on
  * the same context, and doing so before every few computations involving secret
- * keys is recommended as a defense-in-depth measure.
+ * keys is recommended as a defense-in-depth measure. Randomization of the static
+ * context secp256k1_context_static is not supported.
  *
  * Currently, the random seed is mainly used for blinding multiplications of a
  * secret scalar with the elliptic curve base point. Multiplications of this
  * kind are performed by exactly those API functions which are documented to
- * require a context that is not the secp256k1_context_static. As a rule of thumb,
+ * require a context that is not secp256k1_context_static. As a rule of thumb,
  * these are all functions which take a secret key (or a keypair) as an input.
  * A notable exception to that rule is the ECDH module, which relies on a different
  * kind of elliptic curve point multiplication and thus does not benefit from
  * enhanced protection against side-channel leakage currently.
- *
- * It is safe call this function on a copy of secp256k1_context_static in writable
- * memory (e.g., obtained via secp256k1_context_clone). In that case, this
- * function is guaranteed to return 1, but the call will have no effect because
- * the static context (or a copy thereof) is not meant to be randomized.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
-    secp256k1_context* ctx,
+    secp256k1_context *ctx,
     const unsigned char *seed32
 ) SECP256K1_ARG_NONNULL(1);
 
@@ -869,9 +871,9 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
  *          n:          the number of public keys to add together (must be at least 1).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *out,
-    const secp256k1_pubkey * const * ins,
+    const secp256k1_pubkey * const *ins,
     size_t n
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
@@ -892,7 +894,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine(
  *        msglen: length of the message array
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_tagged_sha256(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *hash32,
     const unsigned char *tag,
     size_t taglen,

include/secp256k1_ecdh.h

@@ -27,11 +27,11 @@ typedef int (*secp256k1_ecdh_hash_function)(
 
 /** An implementation of SHA256 hash function that applies to compressed public key.
  * Populates the output parameter with 32 bytes. */
-SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_sha256;
+SECP256K1_API const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_sha256;
 
 /** A default ECDH hash function (currently equal to secp256k1_ecdh_hash_function_sha256).
  * Populates the output parameter with 32 bytes. */
-SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_default;
+SECP256K1_API const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_default;
 
 /** Compute an EC Diffie-Hellman secret in constant time
  *
@@ -48,7 +48,7 @@ SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_func
  *                       (can be NULL for secp256k1_ecdh_hash_function_sha256).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh(
-  const secp256k1_context* ctx,
+  const secp256k1_context *ctx,
   unsigned char *output,
   const secp256k1_pubkey *pubkey,
   const unsigned char *seckey,

include/secp256k1_ellswift.h

@@ -0,0 +1,200 @@
+#ifndef SECP256K1_ELLSWIFT_H
+#define SECP256K1_ELLSWIFT_H
+
+#include "secp256k1.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* This module provides an implementation of ElligatorSwift as well as a
+ * version of x-only ECDH using it (including compatibility with BIP324).
+ *
+ * ElligatorSwift is described in https://eprint.iacr.org/2022/759 by
+ * Chavez-Saab, Rodriguez-Henriquez, and Tibouchi. It permits encoding
+ * uniformly chosen public keys as 64-byte arrays which are indistinguishable
+ * from uniformly random arrays.
+ *
+ * Let f be the function from pairs of field elements to point X coordinates,
+ * defined as follows (all operations modulo p = 2^256 - 2^32 - 977)
+ * f(u,t):
+ * - Let C = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852,
+ *   a square root of -3.
+ * - If u=0, set u=1 instead.
+ * - If t=0, set t=1 instead.
+ * - If u^3 + t^2 + 7 = 0, multiply t by 2.
+ * - Let X = (u^3 + 7 - t^2) / (2 * t)
+ * - Let Y = (X + t) / (C * u)
+ * - Return the first in [u + 4 * Y^2, (-X/Y - u) / 2, (X/Y - u) / 2] that is an
+ *   X coordinate on the curve (at least one of them is, for any u and t).
+ *
+ * Then an ElligatorSwift encoding of x consists of the 32-byte big-endian
+ * encodings of field elements u and t concatenated, where f(u,t) = x.
+ * The encoding algorithm is described in the paper, and effectively picks a
+ * uniformly random pair (u,t) among those which encode x.
+ *
+ * If the Y coordinate is relevant, it is given the same parity as t.
+ *
+ * Changes w.r.t. the the paper:
+ * - The u=0, t=0, and u^3+t^2+7=0 conditions result in decoding to the point
+ *   at infinity in the paper. Here they are remapped to finite points.
+ * - The paper uses an additional encoding bit for the parity of y. Here the
+ *   parity of t is used (negating t does not affect the decoded x coordinate,
+ *   so this is possible).
+ *
+ * For mathematical background about the scheme, see the doc/ellswift.md file.
+ */
+
+/** A pointer to a function used by secp256k1_ellswift_xdh to hash the shared X
+ *  coordinate along with the encoded public keys to a uniform shared secret.
+ *
+ *  Returns: 1 if a shared secret was successfully computed.
+ *           0 will cause secp256k1_ellswift_xdh to fail and return 0.
+ *           Other return values are not allowed, and the behaviour of
+ *           secp256k1_ellswift_xdh is undefined for other return values.
+ *  Out:     output:     pointer to an array to be filled by the function
+ *  In:      x32:        pointer to the 32-byte serialized X coordinate
+ *                       of the resulting shared point (will not be NULL)
+ *           ell_a64:    pointer to the 64-byte encoded public key of party A
+ *                       (will not be NULL)
+ *           ell_b64:    pointer to the 64-byte encoded public key of party B
+ *                       (will not be NULL)
+ *           data:       arbitrary data pointer that is passed through
+ */
+typedef int (*secp256k1_ellswift_xdh_hash_function)(
+    unsigned char *output,
+    const unsigned char *x32,
+    const unsigned char *ell_a64,
+    const unsigned char *ell_b64,
+    void *data
+);
+
+/** An implementation of an secp256k1_ellswift_xdh_hash_function which uses
+ *  SHA256(prefix64 || ell_a64 || ell_b64 || x32), where prefix64 is the 64-byte
+ *  array pointed to by data. */
+SECP256K1_API const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_prefix;
+
+/** An implementation of an secp256k1_ellswift_xdh_hash_function compatible with
+ *  BIP324. It returns H_tag(ell_a64 || ell_b64 || x32), where H_tag is the
+ *  BIP340 tagged hash function with tag "bip324_ellswift_xonly_ecdh". Equivalent
+ *  to secp256k1_ellswift_xdh_hash_function_prefix with prefix64 set to
+ *  SHA256("bip324_ellswift_xonly_ecdh")||SHA256("bip324_ellswift_xonly_ecdh").
+ *  The data argument is ignored. */
+SECP256K1_API const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_bip324;
+
+/** Construct a 64-byte ElligatorSwift encoding of a given pubkey.
+ *
+ *  Returns: 1 always.
+ *  Args:    ctx:        pointer to a context object
+ *  Out:     ell64:      pointer to a 64-byte array to be filled
+ *  In:      pubkey:     a pointer to a secp256k1_pubkey containing an
+ *                       initialized public key
+ *           rnd32:      pointer to 32 bytes of randomness
+ *
+ * It is recommended that rnd32 consists of 32 uniformly random bytes, not
+ * known to any adversary trying to detect whether public keys are being
+ * encoded, though 16 bytes of randomness (padded to an array of 32 bytes,
+ * e.g., with zeros) suffice to make the result indistinguishable from
+ * uniform. The randomness in rnd32 must not be a deterministic function of
+ * the pubkey (it can be derived from the private key, though).
+ *
+ * It is not guaranteed that the computed encoding is stable across versions
+ * of the library, even if all arguments to this function (including rnd32)
+ * are the same.
+ *
+ * This function runs in variable time.
+ */
+SECP256K1_API int secp256k1_ellswift_encode(
+    const secp256k1_context *ctx,
+    unsigned char *ell64,
+    const secp256k1_pubkey *pubkey,
+    const unsigned char *rnd32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Decode a 64-bytes ElligatorSwift encoded public key.
+ *
+ *  Returns: always 1
+ *  Args:    ctx:        pointer to a context object
+ *  Out:     pubkey:     pointer to a secp256k1_pubkey that will be filled
+ *  In:      ell64:      pointer to a 64-byte array to decode
+ *
+ * This function runs in variable time.
+ */
+SECP256K1_API int secp256k1_ellswift_decode(
+    const secp256k1_context *ctx,
+    secp256k1_pubkey *pubkey,
+    const unsigned char *ell64
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Compute an ElligatorSwift public key for a secret key.
+ *
+ *  Returns: 1: secret was valid, public key was stored.
+ *           0: secret was invalid, try again.
+ *  Args:    ctx:        pointer to a context object
+ *  Out:     ell64:      pointer to a 64-byte array to receive the ElligatorSwift
+ *                       public key
+ *  In:      seckey32:   pointer to a 32-byte secret key
+ *           auxrnd32:   (optional) pointer to 32 bytes of randomness
+ *
+ * Constant time in seckey and auxrnd32, but not in the resulting public key.
+ *
+ * It is recommended that auxrnd32 contains 32 uniformly random bytes, though
+ * it is optional (and does result in encodings that are indistinguishable from
+ * uniform even without any auxrnd32). It differs from the (mandatory) rnd32
+ * argument to secp256k1_ellswift_encode in this regard.
+ *
+ * This function can be used instead of calling secp256k1_ec_pubkey_create
+ * followed by secp256k1_ellswift_encode. It is safer, as it uses the secret
+ * key as entropy for the encoding (supplemented with auxrnd32, if provided).
+ *
+ * Like secp256k1_ellswift_encode, this function does not guarantee that the
+ * computed encoding is stable across versions of the library, even if all
+ * arguments (including auxrnd32) are the same.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_create(
+    const secp256k1_context *ctx,
+    unsigned char *ell64,
+    const unsigned char *seckey32,
+    const unsigned char *auxrnd32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Given a private key, and ElligatorSwift public keys sent in both directions,
+ *  compute a shared secret using x-only Elliptic Curve Diffie-Hellman (ECDH).
+ *
+ *  Returns: 1: shared secret was successfully computed
+ *           0: secret was invalid or hashfp returned 0
+ *  Args:    ctx:       pointer to a context object.
+ *  Out:     output:    pointer to an array to be filled by hashfp.
+ *  In:      ell_a64:   pointer to the 64-byte encoded public key of party A
+ *                      (will not be NULL)
+ *           ell_b64:   pointer to the 64-byte encoded public key of party B
+ *                      (will not be NULL)
+ *           seckey32:  a pointer to our 32-byte secret key
+ *           party:     boolean indicating which party we are: zero if we are
+ *                      party A, non-zero if we are party B. seckey32 must be
+ *                      the private key corresponding to that party's ell_?64.
+ *                      This correspondence is not checked.
+ *           hashfp:    pointer to a hash function.
+ *           data:      arbitrary data pointer passed through to hashfp.
+ *
+ * Constant time in seckey32.
+ *
+ * This function is more efficient than decoding the public keys, and performing
+ * ECDH on them.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_xdh(
+  const secp256k1_context *ctx,
+  unsigned char *output,
+  const unsigned char *ell_a64,
+  const unsigned char *ell_b64,
+  const unsigned char *seckey32,
+  int party,
+  secp256k1_ellswift_xdh_hash_function hashfp,
+  void *data
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(7);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SECP256K1_ELLSWIFT_H */

include/secp256k1_extrakeys.h

@@ -45,8 +45,8 @@ typedef struct {
  *  In: input32: pointer to a serialized xonly_pubkey.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse(
-    const secp256k1_context* ctx,
-    secp256k1_xonly_pubkey* pubkey,
+    const secp256k1_context *ctx,
+    secp256k1_xonly_pubkey *pubkey,
     const unsigned char *input32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
@@ -59,9 +59,9 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse(
  *  In:    pubkey: a pointer to a secp256k1_xonly_pubkey containing an initialized public key.
  */
 SECP256K1_API int secp256k1_xonly_pubkey_serialize(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *output32,
-    const secp256k1_xonly_pubkey* pubkey
+    const secp256k1_xonly_pubkey *pubkey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Compare two x-only public keys using lexicographic order
@@ -74,9 +74,9 @@ SECP256K1_API int secp256k1_xonly_pubkey_serialize(
  *        pubkey2:  second public key to compare
  */
 SECP256K1_API int secp256k1_xonly_pubkey_cmp(
-    const secp256k1_context* ctx,
-    const secp256k1_xonly_pubkey* pk1,
-    const secp256k1_xonly_pubkey* pk2
+    const secp256k1_context *ctx,
+    const secp256k1_xonly_pubkey *pk1,
+    const secp256k1_xonly_pubkey *pk2
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey.
@@ -91,7 +91,7 @@ SECP256K1_API int secp256k1_xonly_pubkey_cmp(
  *  In:        pubkey: pointer to a public key that is converted.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubkey(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_xonly_pubkey *xonly_pubkey,
     int *pk_parity,
     const secp256k1_pubkey *pubkey
@@ -112,13 +112,13 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubke
  *  Out:  output_pubkey: pointer to a public key to store the result. Will be set
  *                       to an invalid value if this function returns 0.
  *  In: internal_pubkey: pointer to an x-only pubkey to apply the tweak to.
- *              tweak32: pointer to a 32-byte tweak. If the tweak is invalid
- *                       according to secp256k1_ec_seckey_verify, this function
- *                       returns 0. For uniformly random 32-byte arrays the
- *                       chance of being invalid is negligible (around 1 in 2^128).
+ *              tweak32: pointer to a 32-byte tweak, which must be valid
+ *                       according to secp256k1_ec_seckey_verify or 32 zero
+ *                       bytes. For uniformly random 32-byte tweaks, the chance of
+ *                       being invalid is negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *output_pubkey,
     const secp256k1_xonly_pubkey *internal_pubkey,
     const unsigned char *tweak32
@@ -148,7 +148,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add(
  *               tweak32: pointer to a 32-byte tweak.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add_check(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     const unsigned char *tweaked_pubkey32,
     int tweaked_pk_parity,
     const secp256k1_xonly_pubkey *internal_pubkey,
@@ -164,7 +164,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add_
  *  In:   seckey: pointer to a 32-byte secret key.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_keypair *keypair,
     const unsigned char *seckey
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -177,7 +177,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create(
  *  In: keypair: pointer to a keypair.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_sec(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *seckey,
     const secp256k1_keypair *keypair
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -185,13 +185,12 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_sec(
 /** Get the public key from a keypair.
  *
  *  Returns: 1 always.
- *  Args:    ctx: pointer to a context object.
- *  Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to
- *               the keypair public key. If not, it's set to an invalid value.
+ *  Args:   ctx: pointer to a context object.
+ *  Out: pubkey: pointer to a pubkey object, set to the keypair public key.
  *  In: keypair: pointer to a keypair.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey,
     const secp256k1_keypair *keypair
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -203,15 +202,14 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub(
  *
  *  Returns: 1 always.
  *  Args:   ctx: pointer to a context object.
- *  Out: pubkey: pointer to an xonly_pubkey object. If 1 is returned, it is set
- *               to the keypair public key after converting it to an
- *               xonly_pubkey. If not, it's set to an invalid value.
+ *  Out: pubkey: pointer to an xonly_pubkey object, set to the keypair
+ *               public key after converting it to an xonly_pubkey.
  *    pk_parity: Ignored if NULL. Otherwise, pointer to an integer that will be set to the
  *               pk_parity argument of secp256k1_xonly_pubkey_from_pubkey.
  *  In: keypair: pointer to a keypair.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_pub(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_xonly_pubkey *pubkey,
     int *pk_parity,
     const secp256k1_keypair *keypair
@@ -231,13 +229,13 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_pub(
  *  Args:       ctx: pointer to a context object.
  *  In/Out: keypair: pointer to a keypair to apply the tweak to. Will be set to
  *                   an invalid value if this function returns 0.
- *  In:     tweak32: pointer to a 32-byte tweak. If the tweak is invalid according
- *                   to secp256k1_ec_seckey_verify, this function returns 0. For
- *                   uniformly random 32-byte arrays the chance of being invalid
- *                   is negligible (around 1 in 2^128).
+ *  In:     tweak32: pointer to a 32-byte tweak, which must be valid according to
+ *                   secp256k1_ec_seckey_verify or 32 zero bytes. For uniformly
+ *                   random 32-byte tweaks, the chance of being invalid is
+ *                   negligible (around 1 in 2^128).
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_tweak_add(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_keypair *keypair,
     const unsigned char *tweak32
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

include/secp256k1_preallocated.h

@@ -63,8 +63,8 @@ SECP256K1_API size_t secp256k1_context_preallocated_size(
  *  See also secp256k1_context_randomize (in secp256k1.h)
  *  and secp256k1_context_preallocated_destroy.
  */
-SECP256K1_API secp256k1_context* secp256k1_context_preallocated_create(
-    void* prealloc,
+SECP256K1_API secp256k1_context *secp256k1_context_preallocated_create(
+    void *prealloc,
     unsigned int flags
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
 
@@ -75,7 +75,7 @@ SECP256K1_API secp256k1_context* secp256k1_context_preallocated_create(
  *  In:      ctx: an existing context to copy.
  */
 SECP256K1_API size_t secp256k1_context_preallocated_clone_size(
-    const secp256k1_context* ctx
+    const secp256k1_context *ctx
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
 
 /** Copy a secp256k1 context object into caller-provided memory.
@@ -88,15 +88,18 @@ SECP256K1_API size_t secp256k1_context_preallocated_clone_size(
  *  the lifetime of this context object, see the description of
  *  secp256k1_context_preallocated_create for details.
  *
+ *  Cloning secp256k1_context_static is not possible, and should not be emulated by
+ *  the caller (e.g., using memcpy). Create a new context instead.
+ *
  *  Returns: a newly created context object.
- *  Args:    ctx:      an existing context to copy.
+ *  Args:    ctx:      an existing context to copy (not secp256k1_context_static).
  *  In:      prealloc: a pointer to a rewritable contiguous block of memory of
  *                     size at least secp256k1_context_preallocated_size(flags)
  *                     bytes, as detailed above.
  */
-SECP256K1_API secp256k1_context* secp256k1_context_preallocated_clone(
-    const secp256k1_context* ctx,
-    void* prealloc
+SECP256K1_API secp256k1_context *secp256k1_context_preallocated_clone(
+    const secp256k1_context *ctx,
+    void *prealloc
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_WARN_UNUSED_RESULT;
 
 /** Destroy a secp256k1 context object that has been created in
@@ -117,10 +120,11 @@ SECP256K1_API secp256k1_context* secp256k1_context_preallocated_clone(
  *
  *  Args:   ctx: an existing context to destroy, constructed using
  *               secp256k1_context_preallocated_create or
- *               secp256k1_context_preallocated_clone.
+ *               secp256k1_context_preallocated_clone
+ *               (i.e., not secp256k1_context_static).
  */
 SECP256K1_API void secp256k1_context_preallocated_destroy(
-    secp256k1_context* ctx
+    secp256k1_context *ctx
 ) SECP256K1_ARG_NONNULL(1);
 
 #ifdef __cplusplus

include/secp256k1_recovery.h

@@ -34,8 +34,8 @@ typedef struct {
  *        recid:   the recovery id (0, 1, 2 or 3)
  */
 SECP256K1_API int secp256k1_ecdsa_recoverable_signature_parse_compact(
-    const secp256k1_context* ctx,
-    secp256k1_ecdsa_recoverable_signature* sig,
+    const secp256k1_context *ctx,
+    secp256k1_ecdsa_recoverable_signature *sig,
     const unsigned char *input64,
     int recid
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
@@ -48,9 +48,9 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_parse_compact(
  *  In:   sigin:  a pointer to a recoverable signature.
  */
 SECP256K1_API int secp256k1_ecdsa_recoverable_signature_convert(
-    const secp256k1_context* ctx,
-    secp256k1_ecdsa_signature* sig,
-    const secp256k1_ecdsa_recoverable_signature* sigin
+    const secp256k1_context *ctx,
+    secp256k1_ecdsa_signature *sig,
+    const secp256k1_ecdsa_recoverable_signature *sigin
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Serialize an ECDSA signature in compact format (64 bytes + recovery id).
@@ -62,10 +62,10 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_convert(
  *  In:   sig:      a pointer to an initialized signature object.
  */
 SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *output64,
     int *recid,
-    const secp256k1_ecdsa_recoverable_signature* sig
+    const secp256k1_ecdsa_recoverable_signature *sig
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Create a recoverable ECDSA signature.
@@ -82,7 +82,7 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact(
  *                      (can be NULL for secp256k1_nonce_function_default).
  */
 SECP256K1_API int secp256k1_ecdsa_sign_recoverable(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_ecdsa_recoverable_signature *sig,
     const unsigned char *msghash32,
     const unsigned char *seckey,
@@ -100,7 +100,7 @@ SECP256K1_API int secp256k1_ecdsa_sign_recoverable(
  *           msghash32: the 32-byte message hash assumed to be signed.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     secp256k1_pubkey *pubkey,
     const secp256k1_ecdsa_recoverable_signature *sig,
     const unsigned char *msghash32

include/secp256k1_schnorrsig.h

@@ -61,7 +61,7 @@ typedef int (*secp256k1_nonce_function_hardened)(
  *  Therefore, to create BIP-340 compliant signatures, algo must be set to
  *  "BIP0340/nonce" and algolen to 13.
  */
-SECP256K1_API extern const secp256k1_nonce_function_hardened secp256k1_nonce_function_bip340;
+SECP256K1_API const secp256k1_nonce_function_hardened secp256k1_nonce_function_bip340;
 
 /** Data structure that contains additional arguments for schnorrsig_sign_custom.
  *
@@ -82,7 +82,7 @@ SECP256K1_API extern const secp256k1_nonce_function_hardened secp256k1_nonce_fun
 typedef struct {
     unsigned char magic[4];
     secp256k1_nonce_function_hardened noncefp;
-    void* ndata;
+    void *ndata;
 } secp256k1_schnorrsig_extraparams;
 
 #define SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC { 0xda, 0x6f, 0xb3, 0x8c }
@@ -117,7 +117,7 @@ typedef struct {
  *                argument and for guidance if randomness is expensive.
  */
 SECP256K1_API int secp256k1_schnorrsig_sign32(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *sig64,
     const unsigned char *msg32,
     const secp256k1_keypair *keypair,
@@ -127,7 +127,7 @@ SECP256K1_API int secp256k1_schnorrsig_sign32(
 /** Same as secp256k1_schnorrsig_sign32, but DEPRECATED. Will be removed in
  *  future versions. */
 SECP256K1_API int secp256k1_schnorrsig_sign(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *sig64,
     const unsigned char *msg32,
     const secp256k1_keypair *keypair,
@@ -141,15 +141,23 @@ SECP256K1_API int secp256k1_schnorrsig_sign(
  *  variable length messages and accepts a pointer to an extraparams object that
  *  allows customizing signing by passing additional arguments.
  *
- *  Creates the same signatures as schnorrsig_sign if msglen is 32 and the
- *  extraparams.ndata is the same as aux_rand32.
+ *  Equivalent to secp256k1_schnorrsig_sign32(..., aux_rand32) if msglen is 32
+ *  and extraparams is initialized as follows:
+ *  ```
+ *  secp256k1_schnorrsig_extraparams extraparams = SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT;
+ *  extraparams.ndata = (unsigned char*)aux_rand32;
+ *  ```
  *
+ *  Returns 1 on success, 0 on failure.
+ *  Args:   ctx: pointer to a context object (not secp256k1_context_static).
+ *  Out:  sig64: pointer to a 64-byte array to store the serialized signature.
  *  In:     msg: the message being signed. Can only be NULL if msglen is 0.
- *       msglen: length of the message
- *  extraparams: pointer to a extraparams object (can be NULL)
+ *       msglen: length of the message.
+ *      keypair: pointer to an initialized keypair.
+ *  extraparams: pointer to an extraparams object (can be NULL).
  */
 SECP256K1_API int secp256k1_schnorrsig_sign_custom(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     unsigned char *sig64,
     const unsigned char *msg,
     size_t msglen,
@@ -168,7 +176,7 @@ SECP256K1_API int secp256k1_schnorrsig_sign_custom(
  *        pubkey: pointer to an x-only public key to verify with (cannot be NULL)
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorrsig_verify(
-    const secp256k1_context* ctx,
+    const secp256k1_context *ctx,
     const unsigned char *sig64,
     const unsigned char *msg,
     size_t msglen,

libsecp256k1.pc.in

@@ -9,5 +9,4 @@ URL: https://github.com/bitcoin-core/secp256k1
 Version: @PACKAGE_VERSION@
 Cflags: -I${includedir}
 Libs: -L${libdir} -lsecp256k1
-Libs.private: @SECP_LIBS@
 

sage/gen_exhaustive_groups.sage

@@ -1,124 +1,156 @@
 load("secp256k1_params.sage")
 
+MAX_ORDER = 1000
+
+# Set of (curve) orders we have encountered so far.
 orders_done = set()
-results = {}
-first = True
+
+# Map from (subgroup) orders to [b, int(gen.x), int(gen.y), gen, lambda] for those subgroups.
+solutions = {}
+
+# Iterate over curves of the form y^2 = x^3 + B.
 for b in range(1, P):
-    # There are only 6 curves (up to isomorphism) of the form y^2=x^3+B. Stop once we have tried all.
+    # There are only 6 curves (up to isomorphism) of the form y^2 = x^3 + B. Stop once we have tried all.
     if len(orders_done) == 6:
         break
 
     E = EllipticCurve(F, [0, b])
     print("Analyzing curve y^2 = x^3 + %i" % b)
     n = E.order()
+
     # Skip curves with an order we've already tried
     if n in orders_done:
         print("- Isomorphic to earlier curve")
+        print()
         continue
     orders_done.add(n)
+
     # Skip curves isomorphic to the real secp256k1
     if n.is_pseudoprime():
-        print(" - Isomorphic to secp256k1")
+        assert E.is_isomorphic(C)
+        print("- Isomorphic to secp256k1")
+        print()
         continue
 
-    print("- Finding subgroups")
+    print("- Finding prime subgroups")
 
-    # Find what prime subgroups exist
-    for f, _ in n.factor():
-        print("- Analyzing subgroup of order %i" % f)
-        # Skip subgroups of order >1000
-        if f < 4 or f > 1000:
-            print("  - Bad size")
-            continue
+    # Map from group_order to a set of independent generators for that order.
+    curve_gens = {}
 
-        # Iterate over X coordinates until we find one that is on the curve, has order f,
-        # and for which curve isomorphism exists that maps it to X coordinate 1.
-        for x in range(1, P):
-            # Skip X coordinates not on the curve, and construct the full point otherwise.
-            if not E.is_x_coord(x):
+    for g in E.gens():
+        # Find what prime subgroups of group generated by g exist.
+        g_order = g.order()
+        for f, _ in g.order().factor():
+            # Skip subgroups that have bad size.
+            if f < 4:
+                print(f"  - Subgroup of size {f}: too small")
                 continue
-            G = E.lift_x(F(x))
-
-            print("  - Analyzing (multiples of) point with X=%i" % x)
-
-            # Skip points whose order is not a multiple of f. Project the point to have
-            # order f otherwise.
-            if (G.order() % f):
-                print("    - Bad order")
+            if f > MAX_ORDER:
+                print(f"  - Subgroup of size {f}: too large")
                 continue
-            G = G * (G.order() // f)
+
+            # Construct a generator for that subgroup.
+            gen = g * (g_order // f)
+            assert(gen.order() == f)
+
+            # Add to set the minimal multiple of gen.
+            curve_gens.setdefault(f, set()).add(min([j*gen for j in range(1, f)]))
+            print(f"  - Subgroup of size {f}: ok")
+
+    for f in sorted(curve_gens.keys()):
+        print(f"- Constructing group of order {f}")
+        cbrts = sorted([int(c) for c in Integers(f)(1).nth_root(3, all=true) if c != 1])
+        gens = list(curve_gens[f])
+        sol_count = 0
+        no_endo_count = 0
+
+        # Consider all non-zero linear combinations of the independent generators.
+        for j in range(1, f**len(gens)):
+            gen = sum(gens[k] * ((j // f**k) % f) for k in range(len(gens)))
+            assert not gen.is_zero()
+            assert (f*gen).is_zero()
 
             # Find lambda for endomorphism. Skip if none can be found.
             lam = None
-            for l in Integers(f)(1).nth_root(3, all=True):
-                if int(l)*G == E(BETA*G[0], G[1]):
-                    lam = int(l)
+            for l in cbrts:
+                if l*gen == E(BETA*gen[0], gen[1]):
+                    lam = l
                     break
+
             if lam is None:
-                print("    - No endomorphism for this subgroup")
-                break
+                no_endo_count += 1
+            else:
+                sol_count += 1
+                solutions.setdefault(f, []).append((b, int(gen[0]), int(gen[1]), gen, lam))
 
-            # Now look for an isomorphism of the curve that gives this point an X
-            # coordinate equal to 1.
-            # If (x,y) is on y^2 = x^3 + b, then (a^2*x, a^3*y) is on y^2 = x^3 + a^6*b.
-            # So look for m=a^2=1/x.
-            m = F(1)/G[0]
-            if not m.is_square():
-                print("    - No curve isomorphism maps it to a point with X=1")
-                continue
-            a = m.sqrt()
-            rb = a^6*b
-            RE = EllipticCurve(F, [0, rb])
+        print(f"  - Found {sol_count} generators (plus {no_endo_count} without endomorphism)")
 
-            # Use as generator twice the image of G under the above isormorphism.
-            # This means that generator*(1/2 mod f) will have X coordinate 1.
-            RG = RE(1, a^3*G[1]) * 2
-            # And even Y coordinate.
-            if int(RG[1]) % 2:
-                RG = -RG
-            assert(RG.order() == f)
-            assert(lam*RG == RE(BETA*RG[0], RG[1]))
+    print()
 
-            # We have found curve RE:y^2=x^3+rb with generator RG of order f. Remember it
-            results[f] = {"b": rb, "G": RG, "lambda": lam}
-            print("    - Found solution")
-            break
+def output_generator(g, name):
+    print(f"#define {name} SECP256K1_GE_CONST(\\")
+    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x,\\" % tuple((int(g[0]) >> (32 * (7 - i))) & 0xffffffff for i in range(4)))
+    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x,\\" % tuple((int(g[0]) >> (32 * (7 - i))) & 0xffffffff for i in range(4, 8)))
+    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x,\\" % tuple((int(g[1]) >> (32 * (7 - i))) & 0xffffffff for i in range(4)))
+    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x\\" % tuple((int(g[1]) >> (32 * (7 - i))) & 0xffffffff for i in range(4, 8)))
+    print(")")
 
-    print("")
+def output_b(b):
+    print(f"#define SECP256K1_B {int(b)}")
 
-print("")
-print("")
-print("/* To be put in src/group_impl.h: */")
+print()
+print("To be put in src/group_impl.h:")
+print()
+print("/* Begin of section generated by sage/gen_exhaustive_groups.sage. */")
+for f in sorted(solutions.keys()):
+    # Use as generator/2 the one with lowest b, and lowest (x, y) generator (interpreted as non-negative integers).
+    b, _, _, HALF_G, lam = min(solutions[f])
+    output_generator(2 * HALF_G, f"SECP256K1_G_ORDER_{f}")
+print("/** Generator for secp256k1, value 'g' defined in")
+print(" *  \"Standards for Efficient Cryptography\" (SEC2) 2.7.1.")
+print(" */")
+output_generator(G, "SECP256K1_G")
+print("/* These exhaustive group test orders and generators are chosen such that:")
+print(" * - The field size is equal to that of secp256k1, so field code is the same.")
+print(" * - The curve equation is of the form y^2=x^3+B for some small constant B.")
+print(" * - The subgroup has a generator 2*P, where P.x is as small as possible.")
+print(f" * - The subgroup has size less than {MAX_ORDER} to permit exhaustive testing.")
+print(" * - The subgroup admits an endomorphism of the form lambda*(x,y) == (beta*x,y).")
+print(" */")
+print("#if defined(EXHAUSTIVE_TEST_ORDER)")
 first = True
-for f in sorted(results.keys()):
-    b = results[f]["b"]
-    G = results[f]["G"]
-    print("#  %s EXHAUSTIVE_TEST_ORDER == %i" % ("if" if first else "elif", f))
+for f in sorted(solutions.keys()):
+    b, _, _, _, lam = min(solutions[f])
+    print(f"#  {'if' if first else 'elif'} EXHAUSTIVE_TEST_ORDER == {f}")
     first = False
-    print("static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_GE_CONST(")
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x," % tuple((int(G[0]) >> (32 * (7 - i))) & 0xffffffff for i in range(4)))
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x," % tuple((int(G[0]) >> (32 * (7 - i))) & 0xffffffff for i in range(4, 8)))
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x," % tuple((int(G[1]) >> (32 * (7 - i))) & 0xffffffff for i in range(4)))
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x" % tuple((int(G[1]) >> (32 * (7 - i))) & 0xffffffff for i in range(4, 8)))
-    print(");")
-    print("static const secp256k1_fe secp256k1_fe_const_b = SECP256K1_FE_CONST(")
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x," % tuple((int(b) >> (32 * (7 - i))) & 0xffffffff for i in range(4)))
-    print("    0x%08x, 0x%08x, 0x%08x, 0x%08x" % tuple((int(b) >> (32 * (7 - i))) & 0xffffffff for i in range(4, 8)))
-    print(");")
+    print()
+    print(f"static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G_ORDER_{f};")
+    output_b(b)
+    print()
 print("#  else")
 print("#    error No known generator for the specified exhaustive test group order.")
 print("#  endif")
+print("#else")
+print()
+print("static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G;")
+output_b(7)
+print()
+print("#endif")
+print("/* End of section generated by sage/gen_exhaustive_groups.sage. */")
 
-print("")
-print("")
-print("/* To be put in src/scalar_impl.h: */")
+
+print()
+print()
+print("To be put in src/scalar_impl.h:")
+print()
+print("/* Begin of section generated by sage/gen_exhaustive_groups.sage. */")
 first = True
-for f in sorted(results.keys()):
-    lam = results[f]["lambda"]
+for f in sorted(solutions.keys()):
+    _, _, _, _, lam = min(solutions[f])
     print("#  %s EXHAUSTIVE_TEST_ORDER == %i" % ("if" if first else "elif", f))
     first = False
     print("#    define EXHAUSTIVE_TEST_LAMBDA %i" % lam)
 print("#  else")
 print("#    error No known lambda for the specified exhaustive test group order.")
 print("#  endif")
-print("")
+print("/* End of section generated by sage/gen_exhaustive_groups.sage. */")

sage/group_prover.sage

@@ -198,7 +198,7 @@ def normalize_factor(p):
   (8) * (-bx + ax)^3
   ```
   """
-  # Assert p is not 0 and that its non-zero coeffients are coprime.
+  # Assert p is not 0 and that its non-zero coefficients are coprime.
   # (We could just work with the primitive part p/p.content() but we want to be
   # aware if factor() does not return a primitive part in future sage versions.)
   assert p.content() == 1

sage/prove_group_implementations.sage

@@ -148,7 +148,7 @@ def formula_secp256k1_gej_add_ge(branch, a, b):
   zeroes = {}
   nonzeroes = {}
   a_infinity = False
-  if (branch & 4) != 0:
+  if (branch & 2) != 0:
     nonzeroes.update({a.Infinity : 'a_infinite'})
     a_infinity = True
   else:
@@ -167,15 +167,11 @@ def formula_secp256k1_gej_add_ge(branch, a, b):
   m_alt = -u2
   tt = u1 * m_alt
   rr = rr + tt
-  degenerate = (branch & 3) == 3
-  if (branch & 1) != 0:
+  degenerate = (branch & 1) != 0
+  if degenerate:
     zeroes.update({m : 'm_zero'})
   else:
     nonzeroes.update({m : 'm_nonzero'})
-  if (branch & 2) != 0:
-    zeroes.update({rr : 'rr_zero'})
-  else:
-    nonzeroes.update({rr : 'rr_nonzero'})
   rr_alt = s1
   rr_alt = rr_alt * 2
   m_alt = m_alt + u1
@@ -190,13 +186,6 @@ def formula_secp256k1_gej_add_ge(branch, a, b):
     n = m
   t = rr_alt^2
   rz = a.Z * m_alt
-  infinity = False
-  if (branch & 8) != 0:
-    if not a_infinity:
-      infinity = True
-    zeroes.update({rz : 'r.z=0'})
-  else:
-    nonzeroes.update({rz : 'r.z!=0'})
   t = t + q
   rx = t
   t = t * 2
@@ -209,8 +198,11 @@ def formula_secp256k1_gej_add_ge(branch, a, b):
     rx = b.X
     ry = b.Y
     rz = 1
-  if infinity:
+  if (branch & 4) != 0:
+    zeroes.update({rz : 'r.z = 0'})
     return (constraints(zero={b.Z - 1 : 'b.z=1', b.Infinity : 'b_finite'}), constraints(zero=zeroes, nonzero=nonzeroes), point_at_infinity())
+  else:
+    nonzeroes.update({rz : 'r.z != 0'})
   return (constraints(zero={b.Z - 1 : 'b.z=1', b.Infinity : 'b_finite'}), constraints(zero=zeroes, nonzero=nonzeroes), jacobianpoint(rx, ry, rz))
 
 def formula_secp256k1_gej_add_ge_old(branch, a, b):
@@ -280,14 +272,14 @@ if __name__ == "__main__":
   success = success & check_symbolic_jacobian_weierstrass("secp256k1_gej_add_var", 0, 7, 5, formula_secp256k1_gej_add_var)
   success = success & check_symbolic_jacobian_weierstrass("secp256k1_gej_add_ge_var", 0, 7, 5, formula_secp256k1_gej_add_ge_var)
   success = success & check_symbolic_jacobian_weierstrass("secp256k1_gej_add_zinv_var", 0, 7, 5, formula_secp256k1_gej_add_zinv_var)
-  success = success & check_symbolic_jacobian_weierstrass("secp256k1_gej_add_ge", 0, 7, 16, formula_secp256k1_gej_add_ge)
+  success = success & check_symbolic_jacobian_weierstrass("secp256k1_gej_add_ge", 0, 7, 8, formula_secp256k1_gej_add_ge)
   success = success & (not check_symbolic_jacobian_weierstrass("secp256k1_gej_add_ge_old [should fail]", 0, 7, 4, formula_secp256k1_gej_add_ge_old))
 
   if len(sys.argv) >= 2 and sys.argv[1] == "--exhaustive":
     success = success & check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_var", 0, 7, 5, formula_secp256k1_gej_add_var, 43)
     success = success & check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_ge_var", 0, 7, 5, formula_secp256k1_gej_add_ge_var, 43)
     success = success & check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_zinv_var", 0, 7, 5, formula_secp256k1_gej_add_zinv_var, 43)
-    success = success & check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_ge", 0, 7, 16, formula_secp256k1_gej_add_ge, 43)
+    success = success & check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_ge", 0, 7, 8, formula_secp256k1_gej_add_ge, 43)
     success = success & (not check_exhaustive_jacobian_weierstrass("secp256k1_gej_add_ge_old [should fail]", 0, 7, 4, formula_secp256k1_gej_add_ge_old, 43))
 
   sys.exit(int(not success))

src/CMakeLists.txt

@@ -0,0 +1,173 @@
+# Must be included before CMAKE_INSTALL_INCLUDEDIR is used.
+include(GNUInstallDirs)
+
+add_library(secp256k1_precomputed OBJECT EXCLUDE_FROM_ALL
+  precomputed_ecmult.c
+  precomputed_ecmult_gen.c
+)
+
+# Add objects explicitly rather than linking to the object libs to keep them
+# from being exported.
+add_library(secp256k1 secp256k1.c $<TARGET_OBJECTS:secp256k1_precomputed>)
+
+add_library(secp256k1_asm INTERFACE)
+if(SECP256K1_ASM STREQUAL "arm32")
+  add_library(secp256k1_asm_arm OBJECT EXCLUDE_FROM_ALL)
+  target_sources(secp256k1_asm_arm PUBLIC
+    asm/field_10x26_arm.s
+  )
+  target_sources(secp256k1 PRIVATE $<TARGET_OBJECTS:secp256k1_asm_arm>)
+  target_link_libraries(secp256k1_asm INTERFACE secp256k1_asm_arm)
+endif()
+
+if(WIN32)
+  # Define our export symbol only for shared libs.
+  set_target_properties(secp256k1 PROPERTIES DEFINE_SYMBOL SECP256K1_DLL_EXPORT)
+  target_compile_definitions(secp256k1 INTERFACE $<$<NOT:$<BOOL:${BUILD_SHARED_LIBS}>>:SECP256K1_STATIC>)
+endif()
+
+# Object libs don't know if they're being built for a shared or static lib.
+# Grab the PIC property from secp256k1 which knows.
+get_target_property(use_pic secp256k1 POSITION_INDEPENDENT_CODE)
+set_target_properties(secp256k1_precomputed PROPERTIES POSITION_INDEPENDENT_CODE ${use_pic})
+
+target_include_directories(secp256k1 INTERFACE
+  # Add the include path for parent projects so that they don't have to manually add it.
+  $<BUILD_INTERFACE:$<$<NOT:$<BOOL:${PROJECT_IS_TOP_LEVEL}>>:${PROJECT_SOURCE_DIR}/include>>
+  $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
+)
+
+# This emulates Libtool to make sure Libtool and CMake agree on the ABI version,
+# see below "Calculate the version variables" in build-aux/ltmain.sh.
+math(EXPR ${PROJECT_NAME}_soversion "${${PROJECT_NAME}_LIB_VERSION_CURRENT} - ${${PROJECT_NAME}_LIB_VERSION_AGE}")
+set_target_properties(secp256k1 PROPERTIES
+  SOVERSION ${${PROJECT_NAME}_soversion}
+)
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  set_target_properties(secp256k1 PROPERTIES
+    VERSION ${${PROJECT_NAME}_soversion}.${${PROJECT_NAME}_LIB_VERSION_AGE}.${${PROJECT_NAME}_LIB_VERSION_REVISION}
+  )
+elseif(APPLE)
+  if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.17)
+    math(EXPR ${PROJECT_NAME}_compatibility_version "${${PROJECT_NAME}_LIB_VERSION_CURRENT} + 1")
+    set_target_properties(secp256k1 PROPERTIES
+      MACHO_COMPATIBILITY_VERSION ${${PROJECT_NAME}_compatibility_version}
+      MACHO_CURRENT_VERSION ${${PROJECT_NAME}_compatibility_version}.${${PROJECT_NAME}_LIB_VERSION_REVISION}
+    )
+    unset(${PROJECT_NAME}_compatibility_version)
+  elseif(BUILD_SHARED_LIBS)
+    message(WARNING
+      "The 'compatibility version' and 'current version' values of the DYLIB "
+      "will diverge from the values set by the GNU Libtool. To ensure "
+      "compatibility, it is recommended to upgrade CMake to at least version 3.17."
+    )
+  endif()
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+  set(${PROJECT_NAME}_windows "secp256k1")
+  if(MSVC)
+    set(${PROJECT_NAME}_windows "${PROJECT_NAME}")
+  endif()
+  set_target_properties(secp256k1 PROPERTIES
+    ARCHIVE_OUTPUT_NAME "${${PROJECT_NAME}_windows}"
+    RUNTIME_OUTPUT_NAME "${${PROJECT_NAME}_windows}-${${PROJECT_NAME}_soversion}"
+  )
+  unset(${PROJECT_NAME}_windows)
+endif()
+unset(${PROJECT_NAME}_soversion)
+
+if(SECP256K1_BUILD_BENCHMARK)
+  add_executable(bench bench.c)
+  target_link_libraries(bench secp256k1)
+  add_executable(bench_internal bench_internal.c)
+  target_link_libraries(bench_internal secp256k1_precomputed secp256k1_asm)
+  add_executable(bench_ecmult bench_ecmult.c)
+  target_link_libraries(bench_ecmult secp256k1_precomputed secp256k1_asm)
+endif()
+
+if(SECP256K1_BUILD_TESTS)
+  add_executable(noverify_tests tests.c)
+  target_link_libraries(noverify_tests secp256k1_precomputed secp256k1_asm)
+  add_test(NAME noverify_tests COMMAND noverify_tests)
+  if(NOT CMAKE_BUILD_TYPE STREQUAL "Coverage")
+    add_executable(tests tests.c)
+    target_compile_definitions(tests PRIVATE VERIFY)
+    target_link_libraries(tests secp256k1_precomputed secp256k1_asm)
+    add_test(NAME tests COMMAND tests)
+  endif()
+endif()
+
+if(SECP256K1_BUILD_EXHAUSTIVE_TESTS)
+  # Note: do not include secp256k1_precomputed in exhaustive_tests (it uses runtime-generated tables).
+  add_executable(exhaustive_tests tests_exhaustive.c)
+  target_link_libraries(exhaustive_tests secp256k1_asm)
+  target_compile_definitions(exhaustive_tests PRIVATE $<$<NOT:$<CONFIG:Coverage>>:VERIFY>)
+  add_test(NAME exhaustive_tests COMMAND exhaustive_tests)
+endif()
+
+if(SECP256K1_BUILD_CTIME_TESTS)
+  add_executable(ctime_tests ctime_tests.c)
+  target_link_libraries(ctime_tests secp256k1)
+endif()
+
+if(SECP256K1_INSTALL)
+  install(TARGETS secp256k1
+    EXPORT ${PROJECT_NAME}-targets
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  )
+  set(${PROJECT_NAME}_headers
+    "${PROJECT_SOURCE_DIR}/include/secp256k1.h"
+    "${PROJECT_SOURCE_DIR}/include/secp256k1_preallocated.h"
+  )
+  if(SECP256K1_ENABLE_MODULE_ECDH)
+    list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_ecdh.h")
+  endif()
+  if(SECP256K1_ENABLE_MODULE_RECOVERY)
+    list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_recovery.h")
+  endif()
+  if(SECP256K1_ENABLE_MODULE_EXTRAKEYS)
+    list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_extrakeys.h")
+  endif()
+  if(SECP256K1_ENABLE_MODULE_SCHNORRSIG)
+    list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_schnorrsig.h")
+  endif()
+  if(SECP256K1_ENABLE_MODULE_ELLSWIFT)
+    list(APPEND ${PROJECT_NAME}_headers "${PROJECT_SOURCE_DIR}/include/secp256k1_ellswift.h")
+  endif()
+  install(FILES ${${PROJECT_NAME}_headers}
+    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  )
+
+  install(EXPORT ${PROJECT_NAME}-targets
+    FILE ${PROJECT_NAME}-targets.cmake
+    NAMESPACE ${PROJECT_NAME}::
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
+  )
+
+  include(CMakePackageConfigHelpers)
+  configure_package_config_file(
+    ${PROJECT_SOURCE_DIR}/cmake/config.cmake.in
+    ${PROJECT_NAME}-config.cmake
+    INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
+    NO_SET_AND_CHECK_MACRO
+  )
+  write_basic_package_version_file(${PROJECT_NAME}-config-version.cmake
+    COMPATIBILITY SameMinorVersion
+  )
+
+  install(
+    FILES
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-config.cmake
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-config-version.cmake
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
+  )
+
+  include(GeneratePkgConfigFile)
+  generate_pkg_config_file(${PROJECT_SOURCE_DIR}/libsecp256k1.pc.in)
+  install(
+    FILES
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}.pc
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig
+  )
+endif()

src/asm/field_10x26_arm.s

@@ -29,6 +29,7 @@ Note:
 	.align	2
 	.global secp256k1_fe_mul_inner
 	.type	secp256k1_fe_mul_inner, %function
+	.hidden secp256k1_fe_mul_inner
 	@ Arguments:
 	@  r0  r      Restrict: can overlap with a, not with b
 	@  r1  a
@@ -516,6 +517,7 @@ secp256k1_fe_mul_inner:
 	.align	2
 	.global secp256k1_fe_sqr_inner
 	.type	secp256k1_fe_sqr_inner, %function
+	.hidden secp256k1_fe_sqr_inner
 	@ Arguments:
 	@  r0  r	 Can overlap with a
 	@  r1  a
@@ -911,3 +913,4 @@ secp256k1_fe_sqr_inner:
 	ldmfd	sp!, {r4, r5, r6, r7, r8, r9, r10, r11, pc}
 	.size	secp256k1_fe_sqr_inner, .-secp256k1_fe_sqr_inner
 
+	.section .note.GNU-stack,"",%progbits

src/bench.c

@@ -11,7 +11,7 @@
 #include "util.h"
 #include "bench.h"
 
-void help(int default_iters) {
+static void help(int default_iters) {
     printf("Benchmarks the following algorithms:\n");
     printf("    - ECDSA signing/verification\n");
 
@@ -38,6 +38,8 @@ void help(int default_iters) {
     printf("    ecdsa             : all ECDSA algorithms--sign, verify, recovery (if enabled)\n");
     printf("    ecdsa_sign        : ECDSA siging algorithm\n");
     printf("    ecdsa_verify      : ECDSA verification algorithm\n");
+    printf("    ec                : all EC public key algorithms (keygen)\n");
+    printf("    ec_keygen         : EC public key generation\n");
 
 #ifdef ENABLE_MODULE_RECOVERY
     printf("    ecdsa_recover     : ECDSA public key recovery algorithm\n");
@@ -53,6 +55,14 @@ void help(int default_iters) {
     printf("    schnorrsig_verify : Schnorr verification algorithm\n");
 #endif
 
+#ifdef ENABLE_MODULE_ELLSWIFT
+    printf("    ellswift          : all ElligatorSwift benchmarks (encode, decode, keygen, ecdh)\n");
+    printf("    ellswift_encode   : ElligatorSwift encoding\n");
+    printf("    ellswift_decode   : ElligatorSwift decoding\n");
+    printf("    ellswift_keygen   : ElligatorSwift key generation\n");
+    printf("    ellswift_ecdh     : ECDH on ElligatorSwift keys\n");
+#endif
+
     printf("\n");
 }
 
@@ -64,11 +74,11 @@ typedef struct {
     size_t siglen;
     unsigned char pubkey[33];
     size_t pubkeylen;
-} bench_verify_data;
+} bench_data;
 
 static void bench_verify(void* arg, int iters) {
     int i;
-    bench_verify_data* data = (bench_verify_data*)arg;
+    bench_data* data = (bench_data*)arg;
 
     for (i = 0; i < iters; i++) {
         secp256k1_pubkey pubkey;
@@ -85,15 +95,9 @@ static void bench_verify(void* arg, int iters) {
     }
 }
 
-typedef struct {
-    secp256k1_context* ctx;
-    unsigned char msg[32];
-    unsigned char key[32];
-} bench_sign_data;
-
 static void bench_sign_setup(void* arg) {
     int i;
-    bench_sign_data *data = (bench_sign_data*)arg;
+    bench_data *data = (bench_data*)arg;
 
     for (i = 0; i < 32; i++) {
         data->msg[i] = i + 1;
@@ -105,7 +109,7 @@ static void bench_sign_setup(void* arg) {
 
 static void bench_sign_run(void* arg, int iters) {
     int i;
-    bench_sign_data *data = (bench_sign_data*)arg;
+    bench_data *data = (bench_data*)arg;
 
     unsigned char sig[74];
     for (i = 0; i < iters; i++) {
@@ -121,6 +125,30 @@ static void bench_sign_run(void* arg, int iters) {
     }
 }
 
+static void bench_keygen_setup(void* arg) {
+    int i;
+    bench_data *data = (bench_data*)arg;
+
+    for (i = 0; i < 32; i++) {
+        data->key[i] = i + 65;
+    }
+}
+
+static void bench_keygen_run(void *arg, int iters) {
+    int i;
+    bench_data *data = (bench_data*)arg;
+
+    for (i = 0; i < iters; i++) {
+        unsigned char pub33[33];
+        size_t len = 33;
+        secp256k1_pubkey pubkey;
+        CHECK(secp256k1_ec_pubkey_create(data->ctx, &pubkey, data->key));
+        CHECK(secp256k1_ec_pubkey_serialize(data->ctx, pub33, &len, &pubkey, SECP256K1_EC_COMPRESSED));
+        memcpy(data->key, pub33 + 1, 32);
+    }
+}
+
+
 #ifdef ENABLE_MODULE_ECDH
 # include "modules/ecdh/bench_impl.h"
 #endif
@@ -133,11 +161,15 @@ static void bench_sign_run(void* arg, int iters) {
 # include "modules/schnorrsig/bench_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_ELLSWIFT
+# include "modules/ellswift/bench_impl.h"
+#endif
+
 int main(int argc, char** argv) {
     int i;
     secp256k1_pubkey pubkey;
     secp256k1_ecdsa_signature sig;
-    bench_verify_data data;
+    bench_data data;
 
     int d = argc == 1;
     int default_iters = 20000;
@@ -145,7 +177,9 @@ int main(int argc, char** argv) {
 
     /* Check for invalid user arguments */
     char* valid_args[] = {"ecdsa", "verify", "ecdsa_verify", "sign", "ecdsa_sign", "ecdh", "recover",
-                         "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign"};
+                         "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign", "ec",
+                         "keygen", "ec_keygen", "ellswift", "encode", "ellswift_encode", "decode",
+                         "ellswift_decode", "ellswift_keygen", "ellswift_ecdh"};
     size_t valid_args_size = sizeof(valid_args)/sizeof(valid_args[0]);
     int invalid_args = have_invalid_args(argc, argv, valid_args, valid_args_size);
 
@@ -187,6 +221,16 @@ int main(int argc, char** argv) {
     }
 #endif
 
+#ifndef ENABLE_MODULE_ELLSWIFT
+    if (have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "ellswift_encode") || have_flag(argc, argv, "ellswift_decode") ||
+        have_flag(argc, argv, "encode") || have_flag(argc, argv, "decode") || have_flag(argc, argv, "ellswift_keygen") ||
+        have_flag(argc, argv, "ellswift_ecdh")) {
+        fprintf(stderr, "./bench: ElligatorSwift module not enabled.\n");
+        fprintf(stderr, "Use ./configure --enable-module-ellswift.\n\n");
+        return 1;
+    }
+#endif
+
     /* ECDSA benchmark */
     data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
 
@@ -207,6 +251,7 @@ int main(int argc, char** argv) {
     if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "verify") || have_flag(argc, argv, "ecdsa_verify")) run_benchmark("ecdsa_verify", bench_verify, NULL, NULL, &data, 10, iters);
 
     if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "sign") || have_flag(argc, argv, "ecdsa_sign")) run_benchmark("ecdsa_sign", bench_sign_run, bench_sign_setup, NULL, &data, 10, iters);
+    if (d || have_flag(argc, argv, "ec") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ec_keygen")) run_benchmark("ec_keygen", bench_keygen_run, bench_keygen_setup, NULL, &data, 10, iters);
 
     secp256k1_context_destroy(data.ctx);
 
@@ -225,5 +270,10 @@ int main(int argc, char** argv) {
     run_schnorrsig_bench(iters, argc, argv);
 #endif
 
+#ifdef ENABLE_MODULE_ELLSWIFT
+    /* ElligatorSwift benchmarks */
+    run_ellswift_bench(iters, argc, argv);
+#endif
+
     return 0;
 }

src/bench.h

@@ -15,7 +15,7 @@
 #if (defined(_MSC_VER) && _MSC_VER >= 1900)
 #  include <time.h>
 #else
-#  include "sys/time.h"
+#  include <sys/time.h>
 #endif
 
 static int64_t gettime_i64(void) {
@@ -38,7 +38,7 @@ static int64_t gettime_i64(void) {
 #define FP_MULT (1000000LL)
 
 /* Format fixed point number. */
-void print_number(const int64_t x) {
+static void print_number(const int64_t x) {
     int64_t x_abs, y;
     int c, i, rounding, g; /* g = integer part size, c = fractional part size */
     size_t ptr;
@@ -95,7 +95,7 @@ void print_number(const int64_t x) {
     printf("%-*s", FP_EXP, &buffer[ptr + g]); /* Prints fractional part */
 }
 
-void run_benchmark(char *name, void (*benchmark)(void*, int), void (*setup)(void*), void (*teardown)(void*, int), void* data, int count, int iter) {
+static void run_benchmark(char *name, void (*benchmark)(void*, int), void (*setup)(void*), void (*teardown)(void*, int), void* data, int count, int iter) {
     int i;
     int64_t min = INT64_MAX;
     int64_t sum = 0;
@@ -129,7 +129,7 @@ void run_benchmark(char *name, void (*benchmark)(void*, int), void (*setup)(void
     printf("\n");
 }
 
-int have_flag(int argc, char** argv, char *flag) {
+static int have_flag(int argc, char** argv, char *flag) {
     char** argm = argv + argc;
     argv++;
     while (argv != argm) {
@@ -145,7 +145,7 @@ int have_flag(int argc, char** argv, char *flag) {
    returns:
       - 1 if the user entered an invalid argument
       - 0 if all the user entered arguments are valid */
-int have_invalid_args(int argc, char** argv, char** valid_args, size_t n) {
+static int have_invalid_args(int argc, char** argv, char** valid_args, size_t n) {
     size_t i;
     int found_valid;
     char** argm = argv + argc;
@@ -167,7 +167,7 @@ int have_invalid_args(int argc, char** argv, char** valid_args, size_t n) {
     return 0;
 }
 
-int get_iters(int default_iters) {
+static int get_iters(int default_iters) {
     char* env = getenv("SECP256K1_BENCH_ITERS");
     if (env) {
         return strtol(env, NULL, 0);
@@ -176,7 +176,7 @@ int get_iters(int default_iters) {
     }
 }
 
-void print_output_table_header_row(void) {
+static void print_output_table_header_row(void) {
     char* bench_str = "Benchmark";     /* left justified */
     char* min_str = "    Min(us)    "; /* center alignment */
     char* avg_str = "    Avg(us)    ";

src/bench_ecmult.c

@@ -18,7 +18,7 @@
 
 #define POINTS 32768
 
-void help(char **argv) {
+static void help(char **argv) {
     printf("Benchmark EC multiplication algorithms\n");
     printf("\n");
     printf("Usage: %s <help|pippenger_wnaf|strauss_wnaf|simple>\n", argv[0]);
@@ -113,7 +113,7 @@ static void bench_ecmult_const(void* arg, int iters) {
     int i;
 
     for (i = 0; i < iters; ++i) {
-        secp256k1_ecmult_const(&data->output[i], &data->pubkeys[(data->offset1+i) % POINTS], &data->scalars[(data->offset2+i) % POINTS], 256);
+        secp256k1_ecmult_const(&data->output[i], &data->pubkeys[(data->offset1+i) % POINTS], &data->scalars[(data->offset2+i) % POINTS]);
     }
 }
 
@@ -138,12 +138,10 @@ static void bench_ecmult_1p_teardown(void* arg, int iters) {
 
 static void bench_ecmult_0p_g(void* arg, int iters) {
     bench_data* data = (bench_data*)arg;
-    secp256k1_scalar zero;
     int i;
 
-    secp256k1_scalar_set_int(&zero, 0);
     for (i = 0; i < iters; ++i) {
-        secp256k1_ecmult(&data->output[i], NULL, &zero, &data->scalars[(data->offset1+i) % POINTS]);
+        secp256k1_ecmult(&data->output[i], NULL, &secp256k1_scalar_zero, &data->scalars[(data->offset1+i) % POINTS]);
     }
 }
 
@@ -246,7 +244,6 @@ static void generate_scalar(uint32_t num, secp256k1_scalar* scalar) {
 
 static void run_ecmult_multi_bench(bench_data* data, size_t count, int includes_g, int num_iters) {
     char str[32];
-    static const secp256k1_scalar zero = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 0);
     size_t iters = 1 + num_iters / count;
     size_t iter;
 
@@ -264,7 +261,7 @@ static void run_ecmult_multi_bench(bench_data* data, size_t count, int includes_
             secp256k1_scalar_add(&total, &total, &tmp);
         }
         secp256k1_scalar_negate(&total, &total);
-        secp256k1_ecmult(&data->expected_output[iter], NULL, &zero, &total);
+        secp256k1_ecmult(&data->expected_output[iter], NULL, &secp256k1_scalar_zero, &total);
     }
 
     /* Run the benchmark. */

src/bench_internal.c

@@ -14,10 +14,28 @@
 #include "field_impl.h"
 #include "group_impl.h"
 #include "scalar_impl.h"
-#include "ecmult_const_impl.h"
 #include "ecmult_impl.h"
 #include "bench.h"
 
+static void help(int default_iters) {
+    printf("Benchmarks various internal routines.\n");
+    printf("\n");
+    printf("The default number of iterations for each benchmark is %d. This can be\n", default_iters);
+    printf("customized using the SECP256K1_BENCH_ITERS environment variable.\n");
+    printf("\n");
+    printf("Usage: ./bench_internal [args]\n");
+    printf("By default, all benchmarks will be run.\n");
+    printf("args:\n");
+    printf("    help       : display this help and exit\n");
+    printf("    scalar     : all scalar operations (add, half, inverse, mul, negate, split)\n");
+    printf("    field      : all field operations (half, inverse, issquare, mul, normalize, sqr, sqrt)\n");
+    printf("    group      : all group operations (add, double, to_affine)\n");
+    printf("    ecmult     : all point multiplication operations (ecmult_wnaf) \n");
+    printf("    hash       : all hash algorithms (hmac, rng6979, sha256)\n");
+    printf("    context    : all context object operations (context_create)\n");
+    printf("\n");
+}
+
 typedef struct {
     secp256k1_scalar scalar[2];
     secp256k1_fe fe[4];
@@ -27,7 +45,7 @@ typedef struct {
     int wnaf[256];
 } bench_inv;
 
-void bench_setup(void* arg) {
+static void bench_setup(void* arg) {
     bench_inv *data = (bench_inv*)arg;
 
     static const unsigned char init[4][32] = {
@@ -65,10 +83,10 @@ void bench_setup(void* arg) {
 
     secp256k1_scalar_set_b32(&data->scalar[0], init[0], NULL);
     secp256k1_scalar_set_b32(&data->scalar[1], init[1], NULL);
-    secp256k1_fe_set_b32(&data->fe[0], init[0]);
-    secp256k1_fe_set_b32(&data->fe[1], init[1]);
-    secp256k1_fe_set_b32(&data->fe[2], init[2]);
-    secp256k1_fe_set_b32(&data->fe[3], init[3]);
+    secp256k1_fe_set_b32_limit(&data->fe[0], init[0]);
+    secp256k1_fe_set_b32_limit(&data->fe[1], init[1]);
+    secp256k1_fe_set_b32_limit(&data->fe[2], init[2]);
+    secp256k1_fe_set_b32_limit(&data->fe[3], init[3]);
     CHECK(secp256k1_ge_set_xo_var(&data->ge[0], &data->fe[0], 0));
     CHECK(secp256k1_ge_set_xo_var(&data->ge[1], &data->fe[1], 1));
     secp256k1_gej_set_ge(&data->gej[0], &data->ge[0]);
@@ -79,7 +97,7 @@ void bench_setup(void* arg) {
     memcpy(data->data + 32, init[1], 32);
 }
 
-void bench_scalar_add(void* arg, int iters) {
+static void bench_scalar_add(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
 
@@ -89,7 +107,7 @@ void bench_scalar_add(void* arg, int iters) {
     CHECK(j <= iters);
 }
 
-void bench_scalar_negate(void* arg, int iters) {
+static void bench_scalar_negate(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -98,7 +116,19 @@ void bench_scalar_negate(void* arg, int iters) {
     }
 }
 
-void bench_scalar_mul(void* arg, int iters) {
+static void bench_scalar_half(void* arg, int iters) {
+    int i;
+    bench_inv *data = (bench_inv*)arg;
+    secp256k1_scalar s = data->scalar[0];
+
+    for (i = 0; i < iters; i++) {
+        secp256k1_scalar_half(&s, &s);
+    }
+
+    data->scalar[0] = s;
+}
+
+static void bench_scalar_mul(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -107,18 +137,19 @@ void bench_scalar_mul(void* arg, int iters) {
     }
 }
 
-void bench_scalar_split(void* arg, int iters) {
+static void bench_scalar_split(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
+    secp256k1_scalar tmp;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_split_lambda(&data->scalar[0], &data->scalar[1], &data->scalar[0]);
-        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
+        secp256k1_scalar_split_lambda(&tmp, &data->scalar[1], &data->scalar[0]);
+        j += secp256k1_scalar_add(&data->scalar[0], &tmp, &data->scalar[1]);
     }
     CHECK(j <= iters);
 }
 
-void bench_scalar_inverse(void* arg, int iters) {
+static void bench_scalar_inverse(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
 
@@ -129,7 +160,7 @@ void bench_scalar_inverse(void* arg, int iters) {
     CHECK(j <= iters);
 }
 
-void bench_scalar_inverse_var(void* arg, int iters) {
+static void bench_scalar_inverse_var(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
 
@@ -140,7 +171,7 @@ void bench_scalar_inverse_var(void* arg, int iters) {
     CHECK(j <= iters);
 }
 
-void bench_field_half(void* arg, int iters) {
+static void bench_field_half(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -149,7 +180,7 @@ void bench_field_half(void* arg, int iters) {
     }
 }
 
-void bench_field_normalize(void* arg, int iters) {
+static void bench_field_normalize(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -158,7 +189,7 @@ void bench_field_normalize(void* arg, int iters) {
     }
 }
 
-void bench_field_normalize_weak(void* arg, int iters) {
+static void bench_field_normalize_weak(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -167,7 +198,7 @@ void bench_field_normalize_weak(void* arg, int iters) {
     }
 }
 
-void bench_field_mul(void* arg, int iters) {
+static void bench_field_mul(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -176,7 +207,7 @@ void bench_field_mul(void* arg, int iters) {
     }
 }
 
-void bench_field_sqr(void* arg, int iters) {
+static void bench_field_sqr(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -185,7 +216,7 @@ void bench_field_sqr(void* arg, int iters) {
     }
 }
 
-void bench_field_inverse(void* arg, int iters) {
+static void bench_field_inverse(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -195,7 +226,7 @@ void bench_field_inverse(void* arg, int iters) {
     }
 }
 
-void bench_field_inverse_var(void* arg, int iters) {
+static void bench_field_inverse_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -205,7 +236,7 @@ void bench_field_inverse_var(void* arg, int iters) {
     }
 }
 
-void bench_field_sqrt(void* arg, int iters) {
+static void bench_field_sqrt(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
     secp256k1_fe t;
@@ -218,7 +249,20 @@ void bench_field_sqrt(void* arg, int iters) {
     CHECK(j <= iters);
 }
 
-void bench_group_double_var(void* arg, int iters) {
+static void bench_field_is_square_var(void* arg, int iters) {
+    int i, j = 0;
+    bench_inv *data = (bench_inv*)arg;
+    secp256k1_fe t = data->fe[0];
+
+    for (i = 0; i < iters; i++) {
+        j += secp256k1_fe_is_square_var(&t);
+        secp256k1_fe_add(&t, &data->fe[1]);
+        secp256k1_fe_normalize_var(&t);
+    }
+    CHECK(j <= iters);
+}
+
+static void bench_group_double_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -227,7 +271,7 @@ void bench_group_double_var(void* arg, int iters) {
     }
 }
 
-void bench_group_add_var(void* arg, int iters) {
+static void bench_group_add_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -236,7 +280,7 @@ void bench_group_add_var(void* arg, int iters) {
     }
 }
 
-void bench_group_add_affine(void* arg, int iters) {
+static void bench_group_add_affine(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -245,7 +289,7 @@ void bench_group_add_affine(void* arg, int iters) {
     }
 }
 
-void bench_group_add_affine_var(void* arg, int iters) {
+static void bench_group_add_affine_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -254,7 +298,7 @@ void bench_group_add_affine_var(void* arg, int iters) {
     }
 }
 
-void bench_group_add_zinv_var(void* arg, int iters) {
+static void bench_group_add_zinv_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -263,7 +307,7 @@ void bench_group_add_zinv_var(void* arg, int iters) {
     }
 }
 
-void bench_group_to_affine_var(void* arg, int iters) {
+static void bench_group_to_affine_var(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
 
@@ -283,7 +327,7 @@ void bench_group_to_affine_var(void* arg, int iters) {
     }
 }
 
-void bench_ecmult_wnaf(void* arg, int iters) {
+static void bench_ecmult_wnaf(void* arg, int iters) {
     int i, bits = 0, overflow = 0;
     bench_inv *data = (bench_inv*)arg;
 
@@ -295,20 +339,7 @@ void bench_ecmult_wnaf(void* arg, int iters) {
     CHECK(bits <= 256*iters);
 }
 
-void bench_wnaf_const(void* arg, int iters) {
-    int i, bits = 0, overflow = 0;
-    bench_inv *data = (bench_inv*)arg;
-
-    for (i = 0; i < iters; i++) {
-        bits += secp256k1_wnaf_const(data->wnaf, &data->scalar[0], WINDOW_A, 256);
-        overflow += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
-    }
-    CHECK(overflow >= 0);
-    CHECK(bits <= 256*iters);
-}
-
-
-void bench_sha256(void* arg, int iters) {
+static void bench_sha256(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
     secp256k1_sha256 sha;
@@ -320,7 +351,7 @@ void bench_sha256(void* arg, int iters) {
     }
 }
 
-void bench_hmac_sha256(void* arg, int iters) {
+static void bench_hmac_sha256(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
     secp256k1_hmac_sha256 hmac;
@@ -332,7 +363,7 @@ void bench_hmac_sha256(void* arg, int iters) {
     }
 }
 
-void bench_rfc6979_hmac_sha256(void* arg, int iters) {
+static void bench_rfc6979_hmac_sha256(void* arg, int iters) {
     int i;
     bench_inv *data = (bench_inv*)arg;
     secp256k1_rfc6979_hmac_sha256 rng;
@@ -343,7 +374,7 @@ void bench_rfc6979_hmac_sha256(void* arg, int iters) {
     }
 }
 
-void bench_context(void* arg, int iters) {
+static void bench_context(void* arg, int iters) {
     int i;
     (void)arg;
     for (i = 0; i < iters; i++) {
@@ -353,10 +384,22 @@ void bench_context(void* arg, int iters) {
 
 int main(int argc, char **argv) {
     bench_inv data;
-    int iters = get_iters(20000);
+    int default_iters = 20000;
+    int iters = get_iters(default_iters);
     int d = argc == 1; /* default */
+
+    if (argc > 1) {
+        if (have_flag(argc, argv, "-h")
+           || have_flag(argc, argv, "--help")
+           || have_flag(argc, argv, "help")) {
+            help(default_iters);
+            return 0;
+        }
+    }
+
     print_output_table_header_row();
 
+    if (d || have_flag(argc, argv, "scalar") || have_flag(argc, argv, "half")) run_benchmark("scalar_half", bench_scalar_half, bench_setup, NULL, &data, 10, iters*100);
     if (d || have_flag(argc, argv, "scalar") || have_flag(argc, argv, "add")) run_benchmark("scalar_add", bench_scalar_add, bench_setup, NULL, &data, 10, iters*100);
     if (d || have_flag(argc, argv, "scalar") || have_flag(argc, argv, "negate")) run_benchmark("scalar_negate", bench_scalar_negate, bench_setup, NULL, &data, 10, iters*100);
     if (d || have_flag(argc, argv, "scalar") || have_flag(argc, argv, "mul")) run_benchmark("scalar_mul", bench_scalar_mul, bench_setup, NULL, &data, 10, iters*10);
@@ -371,6 +414,7 @@ int main(int argc, char **argv) {
     if (d || have_flag(argc, argv, "field") || have_flag(argc, argv, "mul")) run_benchmark("field_mul", bench_field_mul, bench_setup, NULL, &data, 10, iters*10);
     if (d || have_flag(argc, argv, "field") || have_flag(argc, argv, "inverse")) run_benchmark("field_inverse", bench_field_inverse, bench_setup, NULL, &data, 10, iters);
     if (d || have_flag(argc, argv, "field") || have_flag(argc, argv, "inverse")) run_benchmark("field_inverse_var", bench_field_inverse_var, bench_setup, NULL, &data, 10, iters);
+    if (d || have_flag(argc, argv, "field") || have_flag(argc, argv, "issquare")) run_benchmark("field_is_square_var", bench_field_is_square_var, bench_setup, NULL, &data, 10, iters);
     if (d || have_flag(argc, argv, "field") || have_flag(argc, argv, "sqrt")) run_benchmark("field_sqrt", bench_field_sqrt, bench_setup, NULL, &data, 10, iters);
 
     if (d || have_flag(argc, argv, "group") || have_flag(argc, argv, "double")) run_benchmark("group_double_var", bench_group_double_var, bench_setup, NULL, &data, 10, iters*10);
@@ -380,7 +424,6 @@ int main(int argc, char **argv) {
     if (d || have_flag(argc, argv, "group") || have_flag(argc, argv, "add")) run_benchmark("group_add_zinv_var", bench_group_add_zinv_var, bench_setup, NULL, &data, 10, iters*10);
     if (d || have_flag(argc, argv, "group") || have_flag(argc, argv, "to_affine")) run_benchmark("group_to_affine_var", bench_group_to_affine_var, bench_setup, NULL, &data, 10, iters);
 
-    if (d || have_flag(argc, argv, "ecmult") || have_flag(argc, argv, "wnaf")) run_benchmark("wnaf_const", bench_wnaf_const, bench_setup, NULL, &data, 10, iters);
     if (d || have_flag(argc, argv, "ecmult") || have_flag(argc, argv, "wnaf")) run_benchmark("ecmult_wnaf", bench_ecmult_wnaf, bench_setup, NULL, &data, 10, iters);
 
     if (d || have_flag(argc, argv, "hash") || have_flag(argc, argv, "sha256")) run_benchmark("hash_sha256", bench_sha256, bench_setup, NULL, &data, 10, iters);

src/checkmem.h

@@ -0,0 +1,95 @@
+/***********************************************************************
+ * Copyright (c) 2022 Pieter Wuille                                    *
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+/* The code here is inspired by Kris Kwiatkowski's approach in
+ * https://github.com/kriskwiatkowski/pqc/blob/main/src/common/ct_check.h
+ * to provide a general interface for memory-checking mechanisms, primarily
+ * for constant-time checking.
+ */
+
+/* These macros are defined by this header file:
+ *
+ * - SECP256K1_CHECKMEM_ENABLED:
+ *   - 1 if memory-checking integration is available, 0 otherwise.
+ *     This is just a compile-time macro. Use the next macro to check it is actually
+ *     available at runtime.
+ * - SECP256K1_CHECKMEM_RUNNING():
+ *   - Acts like a function call, returning 1 if memory checking is available
+ *     at runtime.
+ * - SECP256K1_CHECKMEM_CHECK(p, len):
+ *   - Assert or otherwise fail in case the len-byte memory block pointed to by p is
+ *     not considered entirely defined.
+ * - SECP256K1_CHECKMEM_CHECK_VERIFY(p, len):
+ *   - Like SECP256K1_CHECKMEM_CHECK, but only works in VERIFY mode.
+ * - SECP256K1_CHECKMEM_UNDEFINE(p, len):
+ *   - marks the len-byte memory block pointed to by p as undefined data (secret data,
+ *     in the context of constant-time checking).
+ * - SECP256K1_CHECKMEM_DEFINE(p, len):
+ *   - marks the len-byte memory pointed to by p as defined data (public data, in the
+ *     context of constant-time checking).
+ *
+ */
+
+#ifndef SECP256K1_CHECKMEM_H
+#define SECP256K1_CHECKMEM_H
+
+/* Define a statement-like macro that ignores the arguments. */
+#define SECP256K1_CHECKMEM_NOOP(p, len) do { (void)(p); (void)(len); } while(0)
+
+/* If compiling under msan, map the SECP256K1_CHECKMEM_* functionality to msan.
+ * Choose this preferentially, even when VALGRIND is defined, as msan-compiled
+ * binaries can't be run under valgrind anyway. */
+#if defined(__has_feature)
+#  if __has_feature(memory_sanitizer)
+#    include <sanitizer/msan_interface.h>
+#    define SECP256K1_CHECKMEM_ENABLED 1
+#    define SECP256K1_CHECKMEM_UNDEFINE(p, len) __msan_allocated_memory((p), (len))
+#    define SECP256K1_CHECKMEM_DEFINE(p, len) __msan_unpoison((p), (len))
+#    define SECP256K1_CHECKMEM_CHECK(p, len) __msan_check_mem_is_initialized((p), (len))
+#    define SECP256K1_CHECKMEM_RUNNING() (1)
+#  endif
+#endif
+
+/* If valgrind integration is desired (through the VALGRIND define), implement the
+ * SECP256K1_CHECKMEM_* macros using valgrind. */
+#if !defined SECP256K1_CHECKMEM_ENABLED
+#  if defined VALGRIND
+#    include <stddef.h>
+#  if defined(__clang__) && defined(__APPLE__)
+#    pragma clang diagnostic push
+#    pragma clang diagnostic ignored "-Wreserved-identifier"
+#  endif
+#    include <valgrind/memcheck.h>
+#  if defined(__clang__) && defined(__APPLE__)
+#    pragma clang diagnostic pop
+#  endif
+#    define SECP256K1_CHECKMEM_ENABLED 1
+#    define SECP256K1_CHECKMEM_UNDEFINE(p, len) VALGRIND_MAKE_MEM_UNDEFINED((p), (len))
+#    define SECP256K1_CHECKMEM_DEFINE(p, len) VALGRIND_MAKE_MEM_DEFINED((p), (len))
+#    define SECP256K1_CHECKMEM_CHECK(p, len) VALGRIND_CHECK_MEM_IS_DEFINED((p), (len))
+     /* VALGRIND_MAKE_MEM_DEFINED returns 0 iff not running on memcheck.
+      * This is more precise than the RUNNING_ON_VALGRIND macro, which
+      * checks for valgrind in general instead of memcheck specifically. */
+#    define SECP256K1_CHECKMEM_RUNNING() (VALGRIND_MAKE_MEM_DEFINED(NULL, 0) != 0)
+#  endif
+#endif
+
+/* As a fall-back, map these macros to dummy statements. */
+#if !defined SECP256K1_CHECKMEM_ENABLED
+#  define SECP256K1_CHECKMEM_ENABLED 0
+#  define SECP256K1_CHECKMEM_UNDEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len))
+#  define SECP256K1_CHECKMEM_DEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len))
+#  define SECP256K1_CHECKMEM_CHECK(p, len) SECP256K1_CHECKMEM_NOOP((p), (len))
+#  define SECP256K1_CHECKMEM_RUNNING() (0)
+#endif
+
+#if defined VERIFY
+#define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_CHECK((p), (len))
+#else
+#define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_NOOP((p), (len))
+#endif
+
+#endif /* SECP256K1_CHECKMEM_H */

src/ctime_tests.c

@@ -4,12 +4,15 @@
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/
 
-#include <valgrind/memcheck.h>
 #include <stdio.h>
 
 #include "../include/secp256k1.h"
 #include "assumptions.h"
-#include "util.h"
+#include "checkmem.h"
+
+#if !SECP256K1_CHECKMEM_ENABLED
+#  error "This tool cannot be compiled without memory-checking interface (valgrind or msan)"
+#endif
 
 #ifdef ENABLE_MODULE_ECDH
 # include "../include/secp256k1_ecdh.h"
@@ -27,16 +30,20 @@
 #include "../include/secp256k1_schnorrsig.h"
 #endif
 
-void run_tests(secp256k1_context *ctx, unsigned char *key);
+#ifdef ENABLE_MODULE_ELLSWIFT
+#include "../include/secp256k1_ellswift.h"
+#endif
+
+static void run_tests(secp256k1_context *ctx, unsigned char *key);
 
 int main(void) {
     secp256k1_context* ctx;
     unsigned char key[32];
     int ret, i;
 
-    if (!RUNNING_ON_VALGRIND) {
-        fprintf(stderr, "This test can only usefully be run inside valgrind.\n");
-        fprintf(stderr, "Usage: libtool --mode=execute valgrind ./valgrind_ctime_test\n");
+    if (!SECP256K1_CHECKMEM_RUNNING()) {
+        fprintf(stderr, "This test can only usefully be run inside valgrind because it was not compiled under msan.\n");
+        fprintf(stderr, "Usage: libtool --mode=execute valgrind ./ctime_tests\n");
         return 1;
     }
     ctx = secp256k1_context_create(SECP256K1_CONTEXT_DECLASSIFY);
@@ -51,16 +58,16 @@ int main(void) {
 
     /* Test context randomisation. Do this last because it leaves the context
      * tainted. */
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_context_randomize(ctx, key);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret);
 
     secp256k1_context_destroy(ctx);
     return 0;
 }
 
-void run_tests(secp256k1_context *ctx, unsigned char *key) {
+static void run_tests(secp256k1_context *ctx, unsigned char *key) {
     secp256k1_ecdsa_signature signature;
     secp256k1_pubkey pubkey;
     size_t siglen = 74;
@@ -77,95 +84,126 @@ void run_tests(secp256k1_context *ctx, unsigned char *key) {
 #ifdef ENABLE_MODULE_EXTRAKEYS
     secp256k1_keypair keypair;
 #endif
+#ifdef ENABLE_MODULE_ELLSWIFT
+    unsigned char ellswift[64];
+    static const unsigned char prefix[64] = {'t', 'e', 's', 't'};
+#endif
 
     for (i = 0; i < 32; i++) {
         msg[i] = i + 1;
     }
 
     /* Test keygen. */
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ec_pubkey_create(ctx, &pubkey, key);
-    VALGRIND_MAKE_MEM_DEFINED(&pubkey, sizeof(secp256k1_pubkey));
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&pubkey, sizeof(secp256k1_pubkey));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret);
     CHECK(secp256k1_ec_pubkey_serialize(ctx, spubkey, &outputlen, &pubkey, SECP256K1_EC_COMPRESSED) == 1);
 
     /* Test signing. */
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ecdsa_sign(ctx, &signature, msg, key, NULL, NULL);
-    VALGRIND_MAKE_MEM_DEFINED(&signature, sizeof(secp256k1_ecdsa_signature));
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&signature, sizeof(secp256k1_ecdsa_signature));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret);
     CHECK(secp256k1_ecdsa_signature_serialize_der(ctx, sig, &siglen, &signature));
 
 #ifdef ENABLE_MODULE_ECDH
     /* Test ECDH. */
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ecdh(ctx, msg, &pubkey, key, NULL, NULL);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 #endif
 
 #ifdef ENABLE_MODULE_RECOVERY
     /* Test signing a recoverable signature. */
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ecdsa_sign_recoverable(ctx, &recoverable_signature, msg, key, NULL, NULL);
-    VALGRIND_MAKE_MEM_DEFINED(&recoverable_signature, sizeof(recoverable_signature));
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&recoverable_signature, sizeof(recoverable_signature));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret);
     CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, &recoverable_signature));
     CHECK(recid >= 0 && recid <= 3);
 #endif
 
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ec_seckey_verify(ctx, key);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_ec_seckey_negate(ctx, key);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
-    VALGRIND_MAKE_MEM_UNDEFINED(msg, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(msg, 32);
     ret = secp256k1_ec_seckey_tweak_add(ctx, key, msg);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
-    VALGRIND_MAKE_MEM_UNDEFINED(msg, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(msg, 32);
     ret = secp256k1_ec_seckey_tweak_mul(ctx, key, msg);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
     /* Test keypair_create and keypair_xonly_tweak_add. */
 #ifdef ENABLE_MODULE_EXTRAKEYS
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_keypair_create(ctx, &keypair, key);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
     /* The tweak is not treated as a secret in keypair_tweak_add */
-    VALGRIND_MAKE_MEM_DEFINED(msg, 32);
+    SECP256K1_CHECKMEM_DEFINE(msg, 32);
     ret = secp256k1_keypair_xonly_tweak_add(ctx, &keypair, msg);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
-    VALGRIND_MAKE_MEM_UNDEFINED(&keypair, sizeof(keypair));
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(&keypair, sizeof(keypair));
     ret = secp256k1_keypair_sec(ctx, key, &keypair);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 #endif
 
 #ifdef ENABLE_MODULE_SCHNORRSIG
-    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
     ret = secp256k1_keypair_create(ctx, &keypair, key);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
     ret = secp256k1_schnorrsig_sign32(ctx, sig, msg, &keypair, NULL);
-    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
     CHECK(ret == 1);
 #endif
+
+#ifdef ENABLE_MODULE_ELLSWIFT
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+    ret = secp256k1_ellswift_create(ctx, ellswift, key, NULL);
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+    CHECK(ret == 1);
+
+    SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+    ret = secp256k1_ellswift_create(ctx, ellswift, key, ellswift);
+    SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+    CHECK(ret == 1);
+
+    for (i = 0; i < 2; i++) {
+        SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+        SECP256K1_CHECKMEM_DEFINE(&ellswift, sizeof(ellswift));
+        ret = secp256k1_ellswift_xdh(ctx, msg, ellswift, ellswift, key, i, secp256k1_ellswift_xdh_hash_function_bip324, NULL);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+
+        SECP256K1_CHECKMEM_UNDEFINE(key, 32);
+        SECP256K1_CHECKMEM_DEFINE(&ellswift, sizeof(ellswift));
+        ret = secp256k1_ellswift_xdh(ctx, msg, ellswift, ellswift, key, i, secp256k1_ellswift_xdh_hash_function_prefix, (void *)prefix);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+    }
+
+#endif
 }

src/ecdsa_impl.h

@@ -16,17 +16,8 @@
 #include "ecdsa.h"
 
 /** Group order for secp256k1 defined as 'n' in "Standards for Efficient Cryptography" (SEC2) 2.7.1
- *  sage: for t in xrange(1023, -1, -1):
- *     ..   p = 2**256 - 2**32 - t
- *     ..   if p.is_prime():
- *     ..     print '%x'%p
- *     ..     break
- *   'fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f'
- *  sage: a = 0
- *  sage: b = 7
- *  sage: F = FiniteField (p)
- *  sage: '%x' % (EllipticCurve ([F (a), F (b)]).order())
- *   'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141'
+ *  $ sage -c 'load("secp256k1_params.sage"); print(hex(N))'
+ *  0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
  */
 static const secp256k1_fe secp256k1_ecdsa_const_order_as_fe = SECP256K1_FE_CONST(
     0xFFFFFFFFUL, 0xFFFFFFFFUL, 0xFFFFFFFFUL, 0xFFFFFFFEUL,
@@ -35,12 +26,8 @@ static const secp256k1_fe secp256k1_ecdsa_const_order_as_fe = SECP256K1_FE_CONST
 
 /** Difference between field and order, values 'p' and 'n' values defined in
  *  "Standards for Efficient Cryptography" (SEC2) 2.7.1.
- *  sage: p = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F
- *  sage: a = 0
- *  sage: b = 7
- *  sage: F = FiniteField (p)
- *  sage: '%x' % (p - EllipticCurve ([F (a), F (b)]).order())
- *   '14551231950b75fc4402da1722fc9baee'
+ *  $ sage -c 'load("secp256k1_params.sage"); print(hex(P-N))'
+ *  0x14551231950b75fc4402da1722fc9baee
  */
 static const secp256k1_fe secp256k1_ecdsa_const_p_minus_order = SECP256K1_FE_CONST(
     0, 0, 0, 1, 0x45512319UL, 0x50B75FC4UL, 0x402DA172UL, 0x2FC9BAEEUL
@@ -79,8 +66,7 @@ static int secp256k1_der_read_len(size_t *len, const unsigned char **sigp, const
     }
     if (lenleft > sizeof(size_t)) {
         /* The resulting length would exceed the range of a size_t, so
-         * certainly longer than the passed array size.
-         */
+         * it is certainly longer than the passed array size. */
         return 0;
     }
     while (lenleft > 0) {
@@ -89,7 +75,9 @@ static int secp256k1_der_read_len(size_t *len, const unsigned char **sigp, const
         lenleft--;
     }
     if (*len > (size_t)(sigend - *sigp)) {
-        /* Result exceeds the length of the passed array. */
+        /* Result exceeds the length of the passed array.
+           (Checking this is the responsibility of the caller but it
+           can't hurt do it here, too.) */
         return 0;
     }
     if (*len < 128) {
@@ -239,7 +227,8 @@ static int secp256k1_ecdsa_sig_verify(const secp256k1_scalar *sigr, const secp25
 }
 #else
     secp256k1_scalar_get_b32(c, sigr);
-    secp256k1_fe_set_b32(&xr, c);
+    /* we can ignore the fe_set_b32_limit return value, because we know the input is in range */
+    (void)secp256k1_fe_set_b32_limit(&xr, c);
 
     /** We now have the recomputed R point in pr, and its claimed x coordinate (modulo n)
      *  in xr. Naively, we would extract the x coordinate from pr (requiring a inversion modulo p),

src/eckey_impl.h

@@ -17,10 +17,10 @@
 static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char *pub, size_t size) {
     if (size == 33 && (pub[0] == SECP256K1_TAG_PUBKEY_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_ODD)) {
         secp256k1_fe x;
-        return secp256k1_fe_set_b32(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == SECP256K1_TAG_PUBKEY_ODD);
+        return secp256k1_fe_set_b32_limit(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == SECP256K1_TAG_PUBKEY_ODD);
     } else if (size == 65 && (pub[0] == SECP256K1_TAG_PUBKEY_UNCOMPRESSED || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
         secp256k1_fe x, y;
-        if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) {
+        if (!secp256k1_fe_set_b32_limit(&x, pub+1) || !secp256k1_fe_set_b32_limit(&y, pub+33)) {
             return 0;
         }
         secp256k1_ge_set_xy(elem, &x, &y);
@@ -59,10 +59,8 @@ static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar *key, const secp25
 
 static int secp256k1_eckey_pubkey_tweak_add(secp256k1_ge *key, const secp256k1_scalar *tweak) {
     secp256k1_gej pt;
-    secp256k1_scalar one;
     secp256k1_gej_set_ge(&pt, key);
-    secp256k1_scalar_set_int(&one, 1);
-    secp256k1_ecmult(&pt, &pt, &one, tweak);
+    secp256k1_ecmult(&pt, &pt, &secp256k1_scalar_one, tweak);
 
     if (secp256k1_gej_is_infinity(&pt)) {
         return 0;
@@ -80,15 +78,13 @@ static int secp256k1_eckey_privkey_tweak_mul(secp256k1_scalar *key, const secp25
 }
 
 static int secp256k1_eckey_pubkey_tweak_mul(secp256k1_ge *key, const secp256k1_scalar *tweak) {
-    secp256k1_scalar zero;
     secp256k1_gej pt;
     if (secp256k1_scalar_is_zero(tweak)) {
         return 0;
     }
 
-    secp256k1_scalar_set_int(&zero, 0);
     secp256k1_gej_set_ge(&pt, key);
-    secp256k1_ecmult(&pt, &pt, tweak, &zero);
+    secp256k1_ecmult(&pt, &pt, tweak, &secp256k1_scalar_zero);
     secp256k1_ge_set_gej(key, &pt);
     return 1;
 }

src/ecmult.h

@@ -22,7 +22,7 @@
 #  pragma message DEBUG_CONFIG_DEF(ECMULT_WINDOW_SIZE)
 #endif
 
-/* Noone will ever need more than a window size of 24. The code might
+/* No one will ever need more than a window size of 24. The code might
  * be correct for larger values of ECMULT_WINDOW_SIZE but this is not
  * tested.
  *

src/ecmult_const.h

@@ -11,11 +11,28 @@
 #include "group.h"
 
 /**
- * Multiply: R = q*A (in constant-time)
- * Here `bits` should be set to the maximum bitlength of the _absolute value_ of `q`, plus
- * one because we internally sometimes add 2 to the number during the WNAF conversion.
- * A must not be infinity.
+ * Multiply: R = q*A (in constant-time for q)
  */
-static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, const secp256k1_scalar *q, int bits);
+static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, const secp256k1_scalar *q);
+
+/**
+ * Same as secp256k1_ecmult_const, but takes in an x coordinate of the base point
+ * only, specified as fraction n/d (numerator/denominator). Only the x coordinate of the result is
+ * returned.
+ *
+ * If known_on_curve is 0, a verification is performed that n/d is a valid X
+ * coordinate, and 0 is returned if not. Otherwise, 1 is returned.
+ *
+ * d being NULL is interpreted as d=1. If non-NULL, d must not be zero. q must not be zero.
+ *
+ * Constant time in the value of q, but not any other inputs.
+ */
+static int secp256k1_ecmult_const_xonly(
+    secp256k1_fe *r,
+    const secp256k1_fe *n,
+    const secp256k1_fe *d,
+    const secp256k1_scalar *q,
+    int known_on_curve
+);
 
 #endif /* SECP256K1_ECMULT_CONST_H */

src/ecmult_const_impl.h

@@ -1,5 +1,5 @@
 /***********************************************************************
- * Copyright (c) 2015 Pieter Wuille, Andrew Poelstra                   *
+ * Copyright (c) 2015, 2022 Pieter Wuille, Andrew Poelstra             *
  * Distributed under the MIT software license, see the accompanying    *
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/
@@ -12,220 +12,388 @@
 #include "ecmult_const.h"
 #include "ecmult_impl.h"
 
+#if defined(EXHAUSTIVE_TEST_ORDER)
+/* We need 2^ECMULT_CONST_GROUP_SIZE - 1 to be less than EXHAUSTIVE_TEST_ORDER, because
+ * the tables cannot have infinities in them (this breaks the effective-affine technique's
+ * z-ratio tracking) */
+#  if EXHAUSTIVE_TEST_ORDER == 199
+#    define ECMULT_CONST_GROUP_SIZE 4
+#  elif EXHAUSTIVE_TEST_ORDER == 13
+#    define ECMULT_CONST_GROUP_SIZE 3
+#  elif EXHAUSTIVE_TEST_ORDER == 7
+#    define ECMULT_CONST_GROUP_SIZE 2
+#  else
+#    error "Unknown EXHAUSTIVE_TEST_ORDER"
+#  endif
+#else
+/* Group size 4 or 5 appears optimal. */
+#  define ECMULT_CONST_GROUP_SIZE 5
+#endif
+
+#define ECMULT_CONST_TABLE_SIZE (1L << (ECMULT_CONST_GROUP_SIZE - 1))
+#define ECMULT_CONST_GROUPS ((129 + ECMULT_CONST_GROUP_SIZE - 1) / ECMULT_CONST_GROUP_SIZE)
+#define ECMULT_CONST_BITS (ECMULT_CONST_GROUPS * ECMULT_CONST_GROUP_SIZE)
+
 /** Fill a table 'pre' with precomputed odd multiples of a.
  *
  *  The resulting point set is brought to a single constant Z denominator, stores the X and Y
- *  coordinates as ge_storage points in pre, and stores the global Z in globalz.
- *  It only operates on tables sized for WINDOW_A wnaf multiples.
+ *  coordinates as ge points in pre, and stores the global Z in globalz.
+ *
+ *  'pre' must be an array of size ECMULT_CONST_TABLE_SIZE.
  */
-static void secp256k1_ecmult_odd_multiples_table_globalz_windowa(secp256k1_ge *pre, secp256k1_fe *globalz, const secp256k1_gej *a) {
-    secp256k1_fe zr[ECMULT_TABLE_SIZE(WINDOW_A)];
+static void secp256k1_ecmult_const_odd_multiples_table_globalz(secp256k1_ge *pre, secp256k1_fe *globalz, const secp256k1_gej *a) {
+    secp256k1_fe zr[ECMULT_CONST_TABLE_SIZE];
 
-    secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), pre, zr, globalz, a);
-    secp256k1_ge_table_set_globalz(ECMULT_TABLE_SIZE(WINDOW_A), pre, zr);
+    secp256k1_ecmult_odd_multiples_table(ECMULT_CONST_TABLE_SIZE, pre, zr, globalz, a);
+    secp256k1_ge_table_set_globalz(ECMULT_CONST_TABLE_SIZE, pre, zr);
 }
 
-/* This is like `ECMULT_TABLE_GET_GE` but is constant time */
-#define ECMULT_CONST_TABLE_GET_GE(r,pre,n,w) do { \
-    int m = 0; \
-    /* Extract the sign-bit for a constant time absolute-value. */ \
-    int mask = (n) >> (sizeof(n) * CHAR_BIT - 1); \
-    int abs_n = ((n) + mask) ^ mask; \
-    int idx_n = abs_n >> 1; \
+/* Given a table 'pre' with odd multiples of a point, put in r the signed-bit multiplication of n with that point.
+ *
+ * For example, if ECMULT_CONST_GROUP_SIZE is 4, then pre is expected to contain 8 entries:
+ * [1*P, 3*P, 5*P, 7*P, 9*P, 11*P, 13*P, 15*P]. n is then expected to be a 4-bit integer (range 0-15), and its
+ * bits are interpreted as signs of powers of two to look up.
+ *
+ * For example, if n=4, which is 0100 in binary, which is interpreted as [- + - -], so the looked up value is
+ * [ -(2^3) + (2^2) - (2^1) - (2^0) ]*P = -7*P. Every valid n translates to an odd number in range [-15,15],
+ * which means we just need to look up one of the precomputed values, and optionally negate it.
+ */
+#define ECMULT_CONST_TABLE_GET_GE(r,pre,n) do { \
+    unsigned int m = 0; \
+    /* If the top bit of n is 0, we want the negation. */ \
+    volatile unsigned int negative = ((n) >> (ECMULT_CONST_GROUP_SIZE - 1)) ^ 1; \
+    /* Let n[i] be the i-th bit of n, then the index is
+     *     sum(cnot(n[i]) * 2^i, i=0..l-2)
+     * where cnot(b) = b if n[l-1] = 1 and 1 - b otherwise.
+     * For example, if n = 4, in binary 0100, the index is 3, in binary 011.
+     *
+     * Proof:
+     *     Let
+     *         x = sum((2*n[i] - 1)*2^i, i=0..l-1)
+     *           = 2*sum(n[i] * 2^i, i=0..l-1) - 2^l + 1
+     *     be the value represented by n.
+     *     The index is (x - 1)/2 if x > 0 and -(x + 1)/2 otherwise.
+     *     Case x > 0:
+     *         n[l-1] = 1
+     *         index = sum(n[i] * 2^i, i=0..l-1) - 2^(l-1)
+     *               = sum(n[i] * 2^i, i=0..l-2)
+     *     Case x <= 0:
+     *         n[l-1] = 0
+     *          index = -(2*sum(n[i] * 2^i, i=0..l-1) - 2^l + 2)/2
+     *                = 2^(l-1) - 1 - sum(n[i] * 2^i, i=0..l-1)
+     *                = sum((1 - n[i]) * 2^i, i=0..l-2)
+     */ \
+    unsigned int index = ((unsigned int)(-negative) ^ n) & ((1U << (ECMULT_CONST_GROUP_SIZE - 1)) - 1U); \
     secp256k1_fe neg_y; \
-    VERIFY_CHECK(((n) & 1) == 1); \
-    VERIFY_CHECK((n) >= -((1 << ((w)-1)) - 1)); \
-    VERIFY_CHECK((n) <=  ((1 << ((w)-1)) - 1)); \
-    VERIFY_SETUP(secp256k1_fe_clear(&(r)->x)); \
-    VERIFY_SETUP(secp256k1_fe_clear(&(r)->y)); \
-    /* Unconditionally set r->x = (pre)[m].x. r->y = (pre)[m].y. because it's either the correct one \
+    VERIFY_CHECK((n) < (1U << ECMULT_CONST_GROUP_SIZE)); \
+    VERIFY_CHECK(index < (1U << (ECMULT_CONST_GROUP_SIZE - 1))); \
+    /* Unconditionally set r->x = (pre)[m].x. r->y = (pre)[m].y. because it's either the correct one
      * or will get replaced in the later iterations, this is needed to make sure `r` is initialized. */ \
     (r)->x = (pre)[m].x; \
     (r)->y = (pre)[m].y; \
-    for (m = 1; m < ECMULT_TABLE_SIZE(w); m++) { \
+    for (m = 1; m < ECMULT_CONST_TABLE_SIZE; m++) { \
         /* This loop is used to avoid secret data in array indices. See
          * the comment in ecmult_gen_impl.h for rationale. */ \
-        secp256k1_fe_cmov(&(r)->x, &(pre)[m].x, m == idx_n); \
-        secp256k1_fe_cmov(&(r)->y, &(pre)[m].y, m == idx_n); \
+        secp256k1_fe_cmov(&(r)->x, &(pre)[m].x, m == index); \
+        secp256k1_fe_cmov(&(r)->y, &(pre)[m].y, m == index); \
     } \
     (r)->infinity = 0; \
     secp256k1_fe_negate(&neg_y, &(r)->y, 1); \
-    secp256k1_fe_cmov(&(r)->y, &neg_y, (n) != abs_n); \
+    secp256k1_fe_cmov(&(r)->y, &neg_y, negative); \
 } while(0)
 
-/** Convert a number to WNAF notation.
- *  The number becomes represented by sum(2^{wi} * wnaf[i], i=0..WNAF_SIZE(w)+1) - return_val.
- *  It has the following guarantees:
- *  - each wnaf[i] an odd integer between -(1 << w) and (1 << w)
- *  - each wnaf[i] is nonzero
- *  - the number of words set is always WNAF_SIZE(w) + 1
- *
- *  Adapted from `The Width-w NAF Method Provides Small Memory and Fast Elliptic Scalar
- *  Multiplications Secure against Side Channel Attacks`, Okeya and Tagaki. M. Joye (Ed.)
- *  CT-RSA 2003, LNCS 2612, pp. 328-443, 2003. Springer-Verlag Berlin Heidelberg 2003
- *
- *  Numbers reference steps of `Algorithm SPA-resistant Width-w NAF with Odd Scalar` on pp. 335
- */
-static int secp256k1_wnaf_const(int *wnaf, const secp256k1_scalar *scalar, int w, int size) {
-    int global_sign;
-    int skew;
-    int word = 0;
+/* For K as defined in the comment of secp256k1_ecmult_const, we have several precomputed
+ * formulas/constants.
+ * - in exhaustive test mode, we give an explicit expression to compute it at compile time: */
+#ifdef EXHAUSTIVE_TEST_ORDER
+static const secp256k1_scalar secp256k1_ecmult_const_K = ((SECP256K1_SCALAR_CONST(0, 0, 0, (1U << (ECMULT_CONST_BITS - 128)) - 2U, 0, 0, 0, 0) + EXHAUSTIVE_TEST_ORDER - 1U) * (1U + EXHAUSTIVE_TEST_LAMBDA)) % EXHAUSTIVE_TEST_ORDER;
+/* - for the real secp256k1 group we have constants for various ECMULT_CONST_BITS values. */
+#elif ECMULT_CONST_BITS == 129
+/* For GROUP_SIZE = 1,3. */
+static const secp256k1_scalar secp256k1_ecmult_const_K = SECP256K1_SCALAR_CONST(0xac9c52b3ul, 0x3fa3cf1ful, 0x5ad9e3fdul, 0x77ed9ba4ul, 0xa880b9fcul, 0x8ec739c2ul, 0xe0cfc810ul, 0xb51283ceul);
+#elif ECMULT_CONST_BITS == 130
+/* For GROUP_SIZE = 2,5. */
+static const secp256k1_scalar secp256k1_ecmult_const_K = SECP256K1_SCALAR_CONST(0xa4e88a7dul, 0xcb13034eul, 0xc2bdd6bful, 0x7c118d6bul, 0x589ae848ul, 0x26ba29e4ul, 0xb5c2c1dcul, 0xde9798d9ul);
+#elif ECMULT_CONST_BITS == 132
+/* For GROUP_SIZE = 4,6 */
+static const secp256k1_scalar secp256k1_ecmult_const_K = SECP256K1_SCALAR_CONST(0x76b1d93dul, 0x0fae3c6bul, 0x3215874bul, 0x94e93813ul, 0x7937fe0dul, 0xb66bcaaful, 0xb3749ca5ul, 0xd7b6171bul);
+#else
+#  error "Unknown ECMULT_CONST_BITS"
+#endif
 
-    /* 1 2 3 */
-    int u_last;
-    int u;
-
-    int flip;
-    secp256k1_scalar s = *scalar;
-
-    VERIFY_CHECK(w > 0);
-    VERIFY_CHECK(size > 0);
-
-    /* Note that we cannot handle even numbers by negating them to be odd, as is
-     * done in other implementations, since if our scalars were specified to have
-     * width < 256 for performance reasons, their negations would have width 256
-     * and we'd lose any performance benefit. Instead, we use a variation of a
-     * technique from Section 4.2 of the Okeya/Tagaki paper, which is to add 1 to the
-     * number we are encoding when it is even, returning a skew value indicating
-     * this, and having the caller compensate after doing the multiplication.
+static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, const secp256k1_scalar *q) {
+    /* The approach below combines the signed-digit logic from Mike Hamburg's
+     * "Fast and compact elliptic-curve cryptography" (https://eprint.iacr.org/2012/309)
+     * Section 3.3, with the GLV endomorphism.
      *
-     * In fact, we _do_ want to negate numbers to minimize their bit-lengths (and in
-     * particular, to ensure that the outputs from the endomorphism-split fit into
-     * 128 bits). If we negate, the parity of our number flips, affecting whether
-     * we want to add to the scalar to ensure that it's odd. */
-    flip = secp256k1_scalar_is_high(&s);
-    skew = flip ^ secp256k1_scalar_is_even(&s);
-    secp256k1_scalar_cadd_bit(&s, 0, skew);
-    global_sign = secp256k1_scalar_cond_negate(&s, flip);
+     * The idea there is to interpret the bits of a scalar as signs (1 = +, 0 = -), and compute a
+     * point multiplication in that fashion. Let v be an n-bit non-negative integer (0 <= v < 2^n),
+     * and v[i] its i'th bit (so v = sum(v[i] * 2^i, i=0..n-1)). Then define:
+     *
+     *   C_l(v, A) = sum((2*v[i] - 1) * 2^i*A, i=0..l-1)
+     *
+     * Then it holds that C_l(v, A) = sum((2*v[i] - 1) * 2^i*A, i=0..l-1)
+     *                              = (2*sum(v[i] * 2^i, i=0..l-1) + 1 - 2^l) * A
+     *                              = (2*v + 1 - 2^l) * A
+     *
+     * Thus, one can compute q*A as C_256((q + 2^256 - 1) / 2, A). This is the basis for the
+     * paper's signed-digit multi-comb algorithm for multiplication using a precomputed table.
+     *
+     * It is appealing to try to combine this with the GLV optimization: the idea that a scalar
+     * s can be written as s1 + lambda*s2, where lambda is a curve-specific constant such that
+     * lambda*A is easy to compute, and where s1 and s2 are small. In particular we have the
+     * secp256k1_scalar_split_lambda function which performs such a split with the resulting s1
+     * and s2 in range (-2^128, 2^128) mod n. This does work, but is uninteresting:
+     *
+     *   To compute q*A:
+     *   - Let s1, s2 = split_lambda(q)
+     *   - Let R1 = C_256((s1 + 2^256 - 1) / 2, A)
+     *   - Let R2 = C_256((s2 + 2^256 - 1) / 2, lambda*A)
+     *   - Return R1 + R2
+     *
+     * The issue is that while s1 and s2 are small-range numbers, (s1 + 2^256 - 1) / 2 (mod n)
+     * and (s2 + 2^256 - 1) / 2 (mod n) are not, undoing the benefit of the splitting.
+     *
+     * To make it work, we want to modify the input scalar q first, before splitting, and then only
+     * add a 2^128 offset of the split results (so that they end up in the single 129-bit range
+     * [0,2^129]). A slightly smaller offset would work due to the bounds on the split, but we pick
+     * 2^128 for simplicity. Let s be the scalar fed to split_lambda, and f(q) the function to
+     * compute it from q:
+     *
+     *   To compute q*A:
+     *   - Compute s = f(q)
+     *   - Let s1, s2 = split_lambda(s)
+     *   - Let v1 = s1 + 2^128 (mod n)
+     *   - Let v2 = s2 + 2^128 (mod n)
+     *   - Let R1 = C_l(v1, A)
+     *   - Let R2 = C_l(v2, lambda*A)
+     *   - Return R1 + R2
+     *
+     * l will thus need to be at least 129, but we may overshoot by a few bits (see
+     * further), so keep it as a variable.
+     *
+     * To solve for s, we reason:
+     *     q*A  = R1 + R2
+     * <=> q*A  = C_l(s1 + 2^128, A) + C_l(s2 + 2^128, lambda*A)
+     * <=> q*A  = (2*(s1 + 2^128) + 1 - 2^l) * A + (2*(s2 + 2^128) + 1 - 2^l) * lambda*A
+     * <=> q*A  = (2*(s1 + s2*lambda) + (2^129 + 1 - 2^l) * (1 + lambda)) * A
+     * <=> q    = 2*(s1 + s2*lambda) + (2^129 + 1 - 2^l) * (1 + lambda) (mod n)
+     * <=> q    = 2*s + (2^129 + 1 - 2^l) * (1 + lambda) (mod n)
+     * <=> s    = (q + (2^l - 2^129 - 1) * (1 + lambda)) / 2 (mod n)
+     * <=> f(q) = (q + K) / 2 (mod n)
+     *            where K = (2^l - 2^129 - 1)*(1 + lambda) (mod n)
+     *
+     * We will process the computation of C_l(v1, A) and C_l(v2, lambda*A) in groups of
+     * ECMULT_CONST_GROUP_SIZE, so we set l to the smallest multiple of ECMULT_CONST_GROUP_SIZE
+     * that is not less than 129; this equals ECMULT_CONST_BITS.
+     */
 
-    /* 4 */
-    u_last = secp256k1_scalar_shr_int(&s, w);
-    do {
-        int even;
+    /* The offset to add to s1 and s2 to make them non-negative. Equal to 2^128. */
+    static const secp256k1_scalar S_OFFSET = SECP256K1_SCALAR_CONST(0, 0, 0, 1, 0, 0, 0, 0);
+    secp256k1_scalar s, v1, v2;
+    secp256k1_ge pre_a[ECMULT_CONST_TABLE_SIZE];
+    secp256k1_ge pre_a_lam[ECMULT_CONST_TABLE_SIZE];
+    secp256k1_fe global_z;
+    int group, i;
 
-        /* 4.1 4.4 */
-        u = secp256k1_scalar_shr_int(&s, w);
-        /* 4.2 */
-        even = ((u & 1) == 0);
-        /* In contrast to the original algorithm, u_last is always > 0 and
-         * therefore we do not need to check its sign. In particular, it's easy
-         * to see that u_last is never < 0 because u is never < 0. Moreover,
-         * u_last is never = 0 because u is never even after a loop
-         * iteration. The same holds analogously for the initial value of
-         * u_last (in the first loop iteration). */
-        VERIFY_CHECK(u_last > 0);
-        VERIFY_CHECK((u_last & 1) == 1);
-        u += even;
-        u_last -= even * (1 << w);
-
-        /* 4.3, adapted for global sign change */
-        wnaf[word++] = u_last * global_sign;
-
-        u_last = u;
-    } while (word * w < size);
-    wnaf[word] = u * global_sign;
-
-    VERIFY_CHECK(secp256k1_scalar_is_zero(&s));
-    VERIFY_CHECK(word == WNAF_SIZE_BITS(size, w));
-    return skew;
-}
-
-static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, const secp256k1_scalar *scalar, int size) {
-    secp256k1_ge pre_a[ECMULT_TABLE_SIZE(WINDOW_A)];
-    secp256k1_ge tmpa;
-    secp256k1_fe Z;
-
-    int skew_1;
-    secp256k1_ge pre_a_lam[ECMULT_TABLE_SIZE(WINDOW_A)];
-    int wnaf_lam[1 + WNAF_SIZE(WINDOW_A - 1)];
-    int skew_lam;
-    secp256k1_scalar q_1, q_lam;
-    int wnaf_1[1 + WNAF_SIZE(WINDOW_A - 1)];
-
-    int i;
-
-    /* build wnaf representation for q. */
-    int rsize = size;
-    if (size > 128) {
-        rsize = 128;
-        /* split q into q_1 and q_lam (where q = q_1 + q_lam*lambda, and q_1 and q_lam are ~128 bit) */
-        secp256k1_scalar_split_lambda(&q_1, &q_lam, scalar);
-        skew_1   = secp256k1_wnaf_const(wnaf_1,   &q_1,   WINDOW_A - 1, 128);
-        skew_lam = secp256k1_wnaf_const(wnaf_lam, &q_lam, WINDOW_A - 1, 128);
-    } else
-    {
-        skew_1   = secp256k1_wnaf_const(wnaf_1, scalar, WINDOW_A - 1, size);
-        skew_lam = 0;
+    /* We're allowed to be non-constant time in the point, and the code below (in particular,
+     * secp256k1_ecmult_const_odd_multiples_table_globalz) cannot deal with infinity in a
+     * constant-time manner anyway. */
+    if (secp256k1_ge_is_infinity(a)) {
+        secp256k1_gej_set_infinity(r);
+        return;
     }
 
-    /* Calculate odd multiples of a.
+    /* Compute v1 and v2. */
+    secp256k1_scalar_add(&s, q, &secp256k1_ecmult_const_K);
+    secp256k1_scalar_half(&s, &s);
+    secp256k1_scalar_split_lambda(&v1, &v2, &s);
+    secp256k1_scalar_add(&v1, &v1, &S_OFFSET);
+    secp256k1_scalar_add(&v2, &v2, &S_OFFSET);
+
+#ifdef VERIFY
+    /* Verify that v1 and v2 are in range [0, 2^129-1]. */
+    for (i = 129; i < 256; ++i) {
+        VERIFY_CHECK(secp256k1_scalar_get_bits(&v1, i, 1) == 0);
+        VERIFY_CHECK(secp256k1_scalar_get_bits(&v2, i, 1) == 0);
+    }
+#endif
+
+    /* Calculate odd multiples of A and A*lambda.
      * All multiples are brought to the same Z 'denominator', which is stored
-     * in Z. Due to secp256k1' isomorphism we can do all operations pretending
+     * in global_z. Due to secp256k1' isomorphism we can do all operations pretending
      * that the Z coordinate was 1, use affine addition formulae, and correct
      * the Z coordinate of the result once at the end.
      */
-    VERIFY_CHECK(!a->infinity);
     secp256k1_gej_set_ge(r, a);
-    secp256k1_ecmult_odd_multiples_table_globalz_windowa(pre_a, &Z, r);
-    for (i = 0; i < ECMULT_TABLE_SIZE(WINDOW_A); i++) {
-        secp256k1_fe_normalize_weak(&pre_a[i].y);
-    }
-    if (size > 128) {
-        for (i = 0; i < ECMULT_TABLE_SIZE(WINDOW_A); i++) {
-            secp256k1_ge_mul_lambda(&pre_a_lam[i], &pre_a[i]);
-        }
-
+    secp256k1_ecmult_const_odd_multiples_table_globalz(pre_a, &global_z, r);
+    for (i = 0; i < ECMULT_CONST_TABLE_SIZE; i++) {
+        secp256k1_ge_mul_lambda(&pre_a_lam[i], &pre_a[i]);
     }
 
-    /* first loop iteration (separated out so we can directly set r, rather
-     * than having it start at infinity, get doubled several times, then have
-     * its new value added to it) */
-    i = wnaf_1[WNAF_SIZE_BITS(rsize, WINDOW_A - 1)];
-    VERIFY_CHECK(i != 0);
-    ECMULT_CONST_TABLE_GET_GE(&tmpa, pre_a, i, WINDOW_A);
-    secp256k1_gej_set_ge(r, &tmpa);
-    if (size > 128) {
-        i = wnaf_lam[WNAF_SIZE_BITS(rsize, WINDOW_A - 1)];
-        VERIFY_CHECK(i != 0);
-        ECMULT_CONST_TABLE_GET_GE(&tmpa, pre_a_lam, i, WINDOW_A);
-        secp256k1_gej_add_ge(r, r, &tmpa);
-    }
-    /* remaining loop iterations */
-    for (i = WNAF_SIZE_BITS(rsize, WINDOW_A - 1) - 1; i >= 0; i--) {
-        int n;
+    /* Next, we compute r = C_l(v1, A) + C_l(v2, lambda*A).
+     *
+     * We proceed in groups of ECMULT_CONST_GROUP_SIZE bits, operating on that many bits
+     * at a time, from high in v1, v2 to low. Call these bits1 (from v1) and bits2 (from v2).
+     *
+     * Now note that ECMULT_CONST_TABLE_GET_GE(&t, pre_a, bits1) loads into t a point equal
+     * to C_{ECMULT_CONST_GROUP_SIZE}(bits1, A), and analogously for pre_lam_a / bits2.
+     * This means that all we need to do is add these looked up values together, multiplied
+     * by 2^(ECMULT_GROUP_SIZE * group).
+     */
+    for (group = ECMULT_CONST_GROUPS - 1; group >= 0; --group) {
+        /* Using the _var get_bits function is ok here, since it's only variable in offset and count, not in the scalar. */
+        unsigned int bits1 = secp256k1_scalar_get_bits_var(&v1, group * ECMULT_CONST_GROUP_SIZE, ECMULT_CONST_GROUP_SIZE);
+        unsigned int bits2 = secp256k1_scalar_get_bits_var(&v2, group * ECMULT_CONST_GROUP_SIZE, ECMULT_CONST_GROUP_SIZE);
+        secp256k1_ge t;
         int j;
-        for (j = 0; j < WINDOW_A - 1; ++j) {
-            secp256k1_gej_double(r, r);
-        }
 
-        n = wnaf_1[i];
-        ECMULT_CONST_TABLE_GET_GE(&tmpa, pre_a, n, WINDOW_A);
-        VERIFY_CHECK(n != 0);
-        secp256k1_gej_add_ge(r, r, &tmpa);
-        if (size > 128) {
-            n = wnaf_lam[i];
-            ECMULT_CONST_TABLE_GET_GE(&tmpa, pre_a_lam, n, WINDOW_A);
-            VERIFY_CHECK(n != 0);
-            secp256k1_gej_add_ge(r, r, &tmpa);
+        ECMULT_CONST_TABLE_GET_GE(&t, pre_a, bits1);
+        if (group == ECMULT_CONST_GROUPS - 1) {
+            /* Directly set r in the first iteration. */
+            secp256k1_gej_set_ge(r, &t);
+        } else {
+            /* Shift the result so far up. */
+            for (j = 0; j < ECMULT_CONST_GROUP_SIZE; ++j) {
+                secp256k1_gej_double(r, r);
+            }
+            secp256k1_gej_add_ge(r, r, &t);
+        }
+        ECMULT_CONST_TABLE_GET_GE(&t, pre_a_lam, bits2);
+        secp256k1_gej_add_ge(r, r, &t);
+    }
+
+    /* Map the result back to the secp256k1 curve from the isomorphic curve. */
+    secp256k1_fe_mul(&r->z, &r->z, &global_z);
+}
+
+static int secp256k1_ecmult_const_xonly(secp256k1_fe* r, const secp256k1_fe *n, const secp256k1_fe *d, const secp256k1_scalar *q, int known_on_curve) {
+
+    /* This algorithm is a generalization of Peter Dettman's technique for
+     * avoiding the square root in a random-basepoint x-only multiplication
+     * on a Weierstrass curve:
+     * https://mailarchive.ietf.org/arch/msg/cfrg/7DyYY6gg32wDgHAhgSb6XxMDlJA/
+     *
+     *
+     * === Background: the effective affine technique ===
+     *
+     * Let phi_u be the isomorphism that maps (x, y) on secp256k1 curve y^2 = x^3 + 7 to
+     * x' = u^2*x, y' = u^3*y on curve y'^2 = x'^3 + u^6*7. This new curve has the same order as
+     * the original (it is isomorphic), but moreover, has the same addition/doubling formulas, as
+     * the curve b=7 coefficient does not appear in those formulas (or at least does not appear in
+     * the formulas implemented in this codebase, both affine and Jacobian). See also Example 9.5.2
+     * in https://www.math.auckland.ac.nz/~sgal018/crypto-book/ch9.pdf.
+     *
+     * This means any linear combination of secp256k1 points can be computed by applying phi_u
+     * (with non-zero u) on all input points (including the generator, if used), computing the
+     * linear combination on the isomorphic curve (using the same group laws), and then applying
+     * phi_u^{-1} to get back to secp256k1.
+     *
+     * Switching to Jacobian coordinates, note that phi_u applied to (X, Y, Z) is simply
+     * (X, Y, Z/u). Thus, if we want to compute (X1, Y1, Z) + (X2, Y2, Z), with identical Z
+     * coordinates, we can use phi_Z to transform it to (X1, Y1, 1) + (X2, Y2, 1) on an isomorphic
+     * curve where the affine addition formula can be used instead.
+     * If (X3, Y3, Z3) = (X1, Y1) + (X2, Y2) on that curve, then our answer on secp256k1 is
+     * (X3, Y3, Z3*Z).
+     *
+     * This is the effective affine technique: if we have a linear combination of group elements
+     * to compute, and all those group elements have the same Z coordinate, we can simply pretend
+     * that all those Z coordinates are 1, perform the computation that way, and then multiply the
+     * original Z coordinate back in.
+     *
+     * The technique works on any a=0 short Weierstrass curve. It is possible to generalize it to
+     * other curves too, but there the isomorphic curves will have different 'a' coefficients,
+     * which typically does affect the group laws.
+     *
+     *
+     * === Avoiding the square root for x-only point multiplication ===
+     *
+     * In this function, we want to compute the X coordinate of q*(n/d, y), for
+     * y = sqrt((n/d)^3 + 7). Its negation would also be a valid Y coordinate, but by convention
+     * we pick whatever sqrt returns (which we assume to be a deterministic function).
+     *
+     * Let g = y^2*d^3 = n^3 + 7*d^3. This also means y = sqrt(g/d^3).
+     * Further let v = sqrt(d*g), which must exist as d*g = y^2*d^4 = (y*d^2)^2.
+     *
+     * The input point (n/d, y) also has Jacobian coordinates:
+     *
+     *     (n/d, y, 1)
+     *   = (n/d * v^2, y * v^3, v)
+     *   = (n/d * d*g, y * sqrt(d^3*g^3), v)
+     *   = (n/d * d*g, sqrt(y^2 * d^3*g^3), v)
+     *   = (n*g, sqrt(g/d^3 * d^3*g^3), v)
+     *   = (n*g, sqrt(g^4), v)
+     *   = (n*g, g^2, v)
+     *
+     * It is easy to verify that both (n*g, g^2, v) and its negation (n*g, -g^2, v) have affine X
+     * coordinate n/d, and this holds even when the square root function doesn't have a
+     * deterministic sign. We choose the (n*g, g^2, v) version.
+     *
+     * Now switch to the effective affine curve using phi_v, where the input point has coordinates
+     * (n*g, g^2). Compute (X, Y, Z) = q * (n*g, g^2) there.
+     *
+     * Back on secp256k1, that means q * (n*g, g^2, v) = (X, Y, v*Z). This last point has affine X
+     * coordinate X / (v^2*Z^2) = X / (d*g*Z^2). Determining the affine Y coordinate would involve
+     * a square root, but as long as we only care about the resulting X coordinate, no square root
+     * is needed anywhere in this computation.
+     */
+
+    secp256k1_fe g, i;
+    secp256k1_ge p;
+    secp256k1_gej rj;
+
+    /* Compute g = (n^3 + B*d^3). */
+    secp256k1_fe_sqr(&g, n);
+    secp256k1_fe_mul(&g, &g, n);
+    if (d) {
+        secp256k1_fe b;
+        VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero(d));
+        secp256k1_fe_sqr(&b, d);
+        VERIFY_CHECK(SECP256K1_B <= 8); /* magnitude of b will be <= 8 after the next call */
+        secp256k1_fe_mul_int(&b, SECP256K1_B);
+        secp256k1_fe_mul(&b, &b, d);
+        secp256k1_fe_add(&g, &b);
+        if (!known_on_curve) {
+            /* We need to determine whether (n/d)^3 + 7 is square.
+             *
+             *     is_square((n/d)^3 + 7)
+             * <=> is_square(((n/d)^3 + 7) * d^4)
+             * <=> is_square((n^3 + 7*d^3) * d)
+             * <=> is_square(g * d)
+             */
+            secp256k1_fe c;
+            secp256k1_fe_mul(&c, &g, d);
+            if (!secp256k1_fe_is_square_var(&c)) return 0;
+        }
+    } else {
+        secp256k1_fe_add_int(&g, SECP256K1_B);
+        if (!known_on_curve) {
+            /* g at this point equals x^3 + 7. Test if it is square. */
+            if (!secp256k1_fe_is_square_var(&g)) return 0;
         }
     }
 
-    {
-        /* Correct for wNAF skew */
-        secp256k1_gej tmpj;
+    /* Compute base point P = (n*g, g^2), the effective affine version of (n*g, g^2, v), which has
+     * corresponding affine X coordinate n/d. */
+    secp256k1_fe_mul(&p.x, &g, n);
+    secp256k1_fe_sqr(&p.y, &g);
+    p.infinity = 0;
 
-        secp256k1_ge_neg(&tmpa, &pre_a[0]);
-        secp256k1_gej_add_ge(&tmpj, r, &tmpa);
-        secp256k1_gej_cmov(r, &tmpj, skew_1);
+    /* Perform x-only EC multiplication of P with q. */
+    VERIFY_CHECK(!secp256k1_scalar_is_zero(q));
+    secp256k1_ecmult_const(&rj, &p, q);
+    VERIFY_CHECK(!secp256k1_gej_is_infinity(&rj));
 
-        if (size > 128) {
-            secp256k1_ge_neg(&tmpa, &pre_a_lam[0]);
-            secp256k1_gej_add_ge(&tmpj, r, &tmpa);
-            secp256k1_gej_cmov(r, &tmpj, skew_lam);
-        }
-    }
+    /* The resulting (X, Y, Z) point on the effective-affine isomorphic curve corresponds to
+     * (X, Y, Z*v) on the secp256k1 curve. The affine version of that has X coordinate
+     * (X / (Z^2*d*g)). */
+    secp256k1_fe_sqr(&i, &rj.z);
+    secp256k1_fe_mul(&i, &i, &g);
+    if (d) secp256k1_fe_mul(&i, &i, d);
+    secp256k1_fe_inv(&i, &i);
+    secp256k1_fe_mul(r, &rj.x, &i);
 
-    secp256k1_fe_mul(&r->z, &r->z, &Z);
+    return 1;
 }
 
 #endif /* SECP256K1_ECMULT_CONST_IMPL_H */

src/ecmult_gen_compute_table_impl.h

@@ -22,6 +22,9 @@ static void secp256k1_ecmult_gen_compute_table(secp256k1_ge_storage* table, cons
     secp256k1_gej nums_gej;
     int i, j;
 
+    VERIFY_CHECK(g > 0);
+    VERIFY_CHECK(n > 0);
+
     /* get the generator */
     secp256k1_gej_set_ge(&gj, gen);
 
@@ -31,7 +34,7 @@ static void secp256k1_ecmult_gen_compute_table(secp256k1_ge_storage* table, cons
         secp256k1_fe nums_x;
         secp256k1_ge nums_ge;
         int r;
-        r = secp256k1_fe_set_b32(&nums_x, nums_b32);
+        r = secp256k1_fe_set_b32_limit(&nums_x, nums_b32);
         (void)r;
         VERIFY_CHECK(r);
         r = secp256k1_ge_set_xo_var(&nums_ge, &nums_x, 0);

src/ecmult_gen_impl.h

@@ -87,7 +87,6 @@ static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const
     secp256k1_fe s;
     unsigned char nonce32[32];
     secp256k1_rfc6979_hmac_sha256 rng;
-    int overflow;
     unsigned char keydata[64];
     if (seed32 == NULL) {
         /* When seed is NULL, reset the initial point and blinding value. */
@@ -106,11 +105,9 @@ static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const
     memcpy(keydata + 32, seed32, 32);
     secp256k1_rfc6979_hmac_sha256_initialize(&rng, keydata, 64);
     memset(keydata, 0, sizeof(keydata));
-    /* Accept unobservably small non-uniformity. */
     secp256k1_rfc6979_hmac_sha256_generate(&rng, nonce32, 32);
-    overflow = !secp256k1_fe_set_b32(&s, nonce32);
-    overflow |= secp256k1_fe_is_zero(&s);
-    secp256k1_fe_cmov(&s, &secp256k1_fe_one, overflow);
+    secp256k1_fe_set_b32_mod(&s, nonce32);
+    secp256k1_fe_cmov(&s, &secp256k1_fe_one, secp256k1_fe_normalizes_to_zero(&s));
     /* Randomize the projection to defend against multiplier sidechannels.
        Do this before our own call to secp256k1_ecmult_gen below. */
     secp256k1_gej_rescale(&ctx->initial, &s);

src/ecmult_impl.h

@@ -97,7 +97,7 @@ static void secp256k1_ecmult_odd_multiples_table(int n, secp256k1_ge *pre_a, sec
     secp256k1_gej_set_ge(&ai, &pre_a[0]);
     ai.z = a->z;
 
-    /* pre_a[0] is the point (a.x*C^2, a.y*C^3, a.z*C) which is equvalent to a.
+    /* pre_a[0] is the point (a.x*C^2, a.y*C^3, a.z*C) which is equivalent to a.
      * Set zr[0] to C, which is the ratio between the omitted z(pre_a[0]) value and a.z.
      */
     zr[0] = d.z;
@@ -114,13 +114,16 @@ static void secp256k1_ecmult_odd_multiples_table(int n, secp256k1_ge *pre_a, sec
     secp256k1_fe_mul(z, &ai.z, &d.z);
 }
 
-#define SECP256K1_ECMULT_TABLE_VERIFY(n,w) \
-    VERIFY_CHECK(((n) & 1) == 1); \
-    VERIFY_CHECK((n) >= -((1 << ((w)-1)) - 1)); \
+SECP256K1_INLINE static void secp256k1_ecmult_table_verify(int n, int w) {
+    (void)n;
+    (void)w;
+    VERIFY_CHECK(((n) & 1) == 1);
+    VERIFY_CHECK((n) >= -((1 << ((w)-1)) - 1));
     VERIFY_CHECK((n) <=  ((1 << ((w)-1)) - 1));
+}
 
 SECP256K1_INLINE static void secp256k1_ecmult_table_get_ge(secp256k1_ge *r, const secp256k1_ge *pre, int n, int w) {
-    SECP256K1_ECMULT_TABLE_VERIFY(n,w)
+    secp256k1_ecmult_table_verify(n,w);
     if (n > 0) {
         *r = pre[(n-1)/2];
     } else {
@@ -130,7 +133,7 @@ SECP256K1_INLINE static void secp256k1_ecmult_table_get_ge(secp256k1_ge *r, cons
 }
 
 SECP256K1_INLINE static void secp256k1_ecmult_table_get_ge_lambda(secp256k1_ge *r, const secp256k1_ge *pre, const secp256k1_fe *x, int n, int w) {
-    SECP256K1_ECMULT_TABLE_VERIFY(n,w)
+    secp256k1_ecmult_table_verify(n,w);
     if (n > 0) {
         secp256k1_ge_set_xy(r, &x[(n-1)/2], &pre[(n-1)/2].y);
     } else {
@@ -140,7 +143,7 @@ SECP256K1_INLINE static void secp256k1_ecmult_table_get_ge_lambda(secp256k1_ge *
 }
 
 SECP256K1_INLINE static void secp256k1_ecmult_table_get_ge_storage(secp256k1_ge *r, const secp256k1_ge_storage *pre, int n, int w) {
-    SECP256K1_ECMULT_TABLE_VERIFY(n,w)
+    secp256k1_ecmult_table_verify(n,w);
     if (n > 0) {
         secp256k1_ge_from_storage(r, &pre[(n-1)/2]);
     } else {
@@ -276,9 +279,6 @@ static void secp256k1_ecmult_strauss_wnaf(const struct secp256k1_strauss_state *
          */
         tmp = a[np];
         if (no) {
-#ifdef VERIFY
-            secp256k1_fe_normalize_var(&Z);
-#endif
             secp256k1_gej_rescale(&tmp, &Z);
         }
         secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), state->pre_a + no * ECMULT_TABLE_SIZE(WINDOW_A), state->aux + no * ECMULT_TABLE_SIZE(WINDOW_A), &Z, &tmp);
@@ -288,7 +288,9 @@ static void secp256k1_ecmult_strauss_wnaf(const struct secp256k1_strauss_state *
     }
 
     /* Bring them to the same Z denominator. */
-    secp256k1_ge_table_set_globalz(ECMULT_TABLE_SIZE(WINDOW_A) * no, state->pre_a, state->aux);
+    if (no) {
+        secp256k1_ge_table_set_globalz(ECMULT_TABLE_SIZE(WINDOW_A) * no, state->pre_a, state->aux);
+    }
 
     for (np = 0; np < no; ++np) {
         for (i = 0; i < ECMULT_TABLE_SIZE(WINDOW_A); i++) {
@@ -680,7 +682,7 @@ static int secp256k1_ecmult_pippenger_batch(const secp256k1_callback* error_call
     }
     state_space->ps = (struct secp256k1_pippenger_point_state *) secp256k1_scratch_alloc(error_callback, scratch, entries * sizeof(*state_space->ps));
     state_space->wnaf_na = (int *) secp256k1_scratch_alloc(error_callback, scratch, entries*(WNAF_SIZE(bucket_window+1)) * sizeof(int));
-    buckets = (secp256k1_gej *) secp256k1_scratch_alloc(error_callback, scratch, (1<<bucket_window) * sizeof(*buckets));
+    buckets = (secp256k1_gej *) secp256k1_scratch_alloc(error_callback, scratch, ((size_t)1 << bucket_window) * sizeof(*buckets));
     if (state_space->ps == NULL || state_space->wnaf_na == NULL || buckets == NULL) {
         secp256k1_scratch_apply_checkpoint(error_callback, scratch, scratch_checkpoint);
         return 0;
@@ -770,14 +772,12 @@ static size_t secp256k1_pippenger_max_points(const secp256k1_callback* error_cal
  * require a scratch space */
 static int secp256k1_ecmult_multi_simple_var(secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points) {
     size_t point_idx;
-    secp256k1_scalar szero;
     secp256k1_gej tmpj;
 
-    secp256k1_scalar_set_int(&szero, 0);
     secp256k1_gej_set_infinity(r);
     secp256k1_gej_set_infinity(&tmpj);
     /* r = inp_g_sc*G */
-    secp256k1_ecmult(r, &tmpj, &szero, inp_g_sc);
+    secp256k1_ecmult(r, &tmpj, &secp256k1_scalar_zero, inp_g_sc);
     for (point_idx = 0; point_idx < n_points; point_idx++) {
         secp256k1_ge point;
         secp256k1_gej pointj;
@@ -825,9 +825,7 @@ static int secp256k1_ecmult_multi_var(const secp256k1_callback* error_callback,
     if (inp_g_sc == NULL && n == 0) {
         return 1;
     } else if (n == 0) {
-        secp256k1_scalar szero;
-        secp256k1_scalar_set_int(&szero, 0);
-        secp256k1_ecmult(r, r, &szero, inp_g_sc);
+        secp256k1_ecmult(r, r, &secp256k1_scalar_zero, inp_g_sc);
         return 1;
     }
     if (scratch == NULL) {

src/field.h

@@ -7,23 +7,36 @@
 #ifndef SECP256K1_FIELD_H
 #define SECP256K1_FIELD_H
 
-/** Field element module.
- *
- *  Field elements can be represented in several ways, but code accessing
- *  it (and implementations) need to take certain properties into account:
- *  - Each field element can be normalized or not.
- *  - Each field element has a magnitude, which represents how far away
- *    its representation is away from normalization. Normalized elements
- *    always have a magnitude of 0 or 1, but a magnitude of 1 doesn't
- *    imply normality.
- */
-
-#if defined HAVE_CONFIG_H
-#include "libsecp256k1-config.h"
-#endif
-
 #include "util.h"
 
+/* This file defines the generic interface for working with secp256k1_fe
+ * objects, which represent field elements (integers modulo 2^256 - 2^32 - 977).
+ *
+ * The actual definition of the secp256k1_fe type depends on the chosen field
+ * implementation; see the field_5x52.h and field_10x26.h files for details.
+ *
+ * All secp256k1_fe objects have implicit properties that determine what
+ * operations are permitted on it. These are purely a function of what
+ * secp256k1_fe_ operations are applied on it, generally (implicitly) fixed at
+ * compile time, and do not depend on the chosen field implementation. Despite
+ * that, what these properties actually entail for the field representation
+ * values depends on the chosen field implementation. These properties are:
+ * - magnitude: an integer in [0,32]
+ * - normalized: 0 or 1; normalized=1 implies magnitude <= 1.
+ *
+ * In VERIFY mode, they are materialized explicitly as fields in the struct,
+ * allowing run-time verification of these properties. In that case, the field
+ * implementation also provides a secp256k1_fe_verify routine to verify that
+ * these fields match the run-time value and perform internal consistency
+ * checks. */
+#ifdef VERIFY
+#  define SECP256K1_FE_VERIFY_FIELDS \
+    int magnitude; \
+    int normalized;
+#else
+#  define SECP256K1_FE_VERIFY_FIELDS
+#endif
+
 #if defined(SECP256K1_WIDEMUL_INT128)
 #include "field_5x52.h"
 #elif defined(SECP256K1_WIDEMUL_INT64)
@@ -32,111 +45,311 @@
 #error "Please select wide multiplication implementation"
 #endif
 
+#ifdef VERIFY
+/* Magnitude and normalized value for constants. */
+#define SECP256K1_FE_VERIFY_CONST(d7, d6, d5, d4, d3, d2, d1, d0) \
+    /* Magnitude is 0 for constant 0; 1 otherwise. */ \
+    , (((d7) | (d6) | (d5) | (d4) | (d3) | (d2) | (d1) | (d0)) != 0) \
+    /* Normalized is 1 unless sum(d_i<<(32*i) for i=0..7) exceeds field modulus. */ \
+    , (!(((d7) & (d6) & (d5) & (d4) & (d3) & (d2)) == 0xfffffffful && ((d1) == 0xfffffffful || ((d1) == 0xfffffffe && (d0 >= 0xfffffc2f)))))
+#else
+#define SECP256K1_FE_VERIFY_CONST(d7, d6, d5, d4, d3, d2, d1, d0)
+#endif
+
+/** This expands to an initializer for a secp256k1_fe valued sum((i*32) * d_i, i=0..7) mod p.
+ *
+ * It has magnitude 1, unless d_i are all 0, in which case the magnitude is 0.
+ * It is normalized, unless sum(2^(i*32) * d_i, i=0..7) >= p.
+ *
+ * SECP256K1_FE_CONST_INNER is provided by the implementation.
+ */
+#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0)) SECP256K1_FE_VERIFY_CONST((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0)) }
+
 static const secp256k1_fe secp256k1_fe_one = SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 1);
 static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
     0x7ae96a2bul, 0x657c0710ul, 0x6e64479eul, 0xac3434e9ul,
     0x9cf04975ul, 0x12f58995ul, 0xc1396c28ul, 0x719501eeul
 );
 
-/** Normalize a field element. This brings the field element to a canonical representation, reduces
- *  its magnitude to 1, and reduces it modulo field size `p`.
+#ifndef VERIFY
+/* In non-VERIFY mode, we #define the fe operations to be identical to their
+ * internal field implementation, to avoid the potential overhead of a
+ * function call (even though presumably inlinable). */
+#  define secp256k1_fe_normalize secp256k1_fe_impl_normalize
+#  define secp256k1_fe_normalize_weak secp256k1_fe_impl_normalize_weak
+#  define secp256k1_fe_normalize_var secp256k1_fe_impl_normalize_var
+#  define secp256k1_fe_normalizes_to_zero secp256k1_fe_impl_normalizes_to_zero
+#  define secp256k1_fe_normalizes_to_zero_var secp256k1_fe_impl_normalizes_to_zero_var
+#  define secp256k1_fe_set_int secp256k1_fe_impl_set_int
+#  define secp256k1_fe_clear secp256k1_fe_impl_clear
+#  define secp256k1_fe_is_zero secp256k1_fe_impl_is_zero
+#  define secp256k1_fe_is_odd secp256k1_fe_impl_is_odd
+#  define secp256k1_fe_cmp_var secp256k1_fe_impl_cmp_var
+#  define secp256k1_fe_set_b32_mod secp256k1_fe_impl_set_b32_mod
+#  define secp256k1_fe_set_b32_limit secp256k1_fe_impl_set_b32_limit
+#  define secp256k1_fe_get_b32 secp256k1_fe_impl_get_b32
+#  define secp256k1_fe_negate_unchecked secp256k1_fe_impl_negate_unchecked
+#  define secp256k1_fe_mul_int_unchecked secp256k1_fe_impl_mul_int_unchecked
+#  define secp256k1_fe_add secp256k1_fe_impl_add
+#  define secp256k1_fe_mul secp256k1_fe_impl_mul
+#  define secp256k1_fe_sqr secp256k1_fe_impl_sqr
+#  define secp256k1_fe_cmov secp256k1_fe_impl_cmov
+#  define secp256k1_fe_to_storage secp256k1_fe_impl_to_storage
+#  define secp256k1_fe_from_storage secp256k1_fe_impl_from_storage
+#  define secp256k1_fe_inv secp256k1_fe_impl_inv
+#  define secp256k1_fe_inv_var secp256k1_fe_impl_inv_var
+#  define secp256k1_fe_get_bounds secp256k1_fe_impl_get_bounds
+#  define secp256k1_fe_half secp256k1_fe_impl_half
+#  define secp256k1_fe_add_int secp256k1_fe_impl_add_int
+#  define secp256k1_fe_is_square_var secp256k1_fe_impl_is_square_var
+#endif /* !defined(VERIFY) */
+
+/** Normalize a field element.
+ *
+ * On input, r must be a valid field element.
+ * On output, r represents the same value but has normalized=1 and magnitude=1.
  */
 static void secp256k1_fe_normalize(secp256k1_fe *r);
 
-/** Weakly normalize a field element: reduce its magnitude to 1, but don't fully normalize. */
+/** Give a field element magnitude 1.
+ *
+ * On input, r must be a valid field element.
+ * On output, r represents the same value but has magnitude=1. Normalized is unchanged.
+ */
 static void secp256k1_fe_normalize_weak(secp256k1_fe *r);
 
-/** Normalize a field element, without constant-time guarantee. */
+/** Normalize a field element, without constant-time guarantee.
+ *
+ * Identical in behavior to secp256k1_fe_normalize, but not constant time in r.
+ */
 static void secp256k1_fe_normalize_var(secp256k1_fe *r);
 
-/** Verify whether a field element represents zero i.e. would normalize to a zero value. */
+/** Determine whether r represents field element 0.
+ *
+ * On input, r must be a valid field element.
+ * Returns whether r = 0 (mod p).
+ */
 static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r);
 
-/** Verify whether a field element represents zero i.e. would normalize to a zero value,
- *  without constant-time guarantee. */
+/** Determine whether r represents field element 0, without constant-time guarantee.
+ *
+ * Identical in behavior to secp256k1_normalizes_to_zero, but not constant time in r.
+ */
 static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r);
 
-/** Set a field element equal to a small (not greater than 0x7FFF), non-negative integer.
- *  Resulting field element is normalized; it has magnitude 0 if a == 0, and magnitude 1 otherwise.
+/** Set a field element to an integer in range [0,0x7FFF].
+ *
+ * On input, r does not need to be initialized, a must be in [0,0x7FFF].
+ * On output, r represents value a, is normalized and has magnitude (a!=0).
  */
 static void secp256k1_fe_set_int(secp256k1_fe *r, int a);
 
-/** Sets a field element equal to zero, initializing all fields. */
+/** Set a field element to 0.
+ *
+ * On input, a does not need to be initialized.
+ * On output, a represents 0, is normalized and has magnitude 0.
+ */
 static void secp256k1_fe_clear(secp256k1_fe *a);
 
-/** Verify whether a field element is zero. Requires the input to be normalized. */
+/** Determine whether a represents field element 0.
+ *
+ * On input, a must be a valid normalized field element.
+ * Returns whether a = 0 (mod p).
+ *
+ * This behaves identical to secp256k1_normalizes_to_zero{,_var}, but requires
+ * normalized input (and is much faster).
+ */
 static int secp256k1_fe_is_zero(const secp256k1_fe *a);
 
-/** Check the "oddness" of a field element. Requires the input to be normalized. */
+/** Determine whether a (mod p) is odd.
+ *
+ * On input, a must be a valid normalized field element.
+ * Returns (int(a) mod p) & 1.
+ */
 static int secp256k1_fe_is_odd(const secp256k1_fe *a);
 
-/** Compare two field elements. Requires magnitude-1 inputs. */
+/** Determine whether two field elements are equal.
+ *
+ * On input, a and b must be valid field elements with magnitudes not exceeding
+ * 1 and 31, respectively.
+ * Returns a = b (mod p).
+ */
 static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b);
 
-/** Same as secp256k1_fe_equal, but may be variable time. */
-static int secp256k1_fe_equal_var(const secp256k1_fe *a, const secp256k1_fe *b);
-
-/** Compare two field elements. Requires both inputs to be normalized */
+/** Compare the values represented by 2 field elements, without constant-time guarantee.
+ *
+ * On input, a and b must be valid normalized field elements.
+ * Returns 1 if a > b, -1 if a < b, and 0 if a = b (comparisons are done as integers
+ * in range 0..p-1).
+ */
 static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b);
 
-/** Set a field element equal to 32-byte big endian value. If successful, the resulting field element is normalized. */
-static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a);
+/** Set a field element equal to the element represented by a provided 32-byte big endian value
+ * interpreted modulo p.
+ *
+ * On input, r does not need to be initialized. a must be a pointer to an initialized 32-byte array.
+ * On output, r = a (mod p). It will have magnitude 1, and not be normalized.
+ */
+static void secp256k1_fe_set_b32_mod(secp256k1_fe *r, const unsigned char *a);
 
-/** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */
+/** Set a field element equal to a provided 32-byte big endian value, checking for overflow.
+ *
+ * On input, r does not need to be initialized. a must be a pointer to an initialized 32-byte array.
+ * On output, r = a if (a < p), it will be normalized with magnitude 1, and 1 is returned.
+ * If a >= p, 0 is returned, and r will be made invalid (and must not be used without overwriting).
+ */
+static int secp256k1_fe_set_b32_limit(secp256k1_fe *r, const unsigned char *a);
+
+/** Convert a field element to 32-byte big endian byte array.
+ * On input, a must be a valid normalized field element, and r a pointer to a 32-byte array.
+ * On output, r = a (mod p).
+ */
 static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a);
 
-/** Set a field element equal to the additive inverse of another. Takes a maximum magnitude of the input
- *  as an argument. The magnitude of the output is one higher. */
-static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k1_fe *a, int m);
+/** Negate a field element.
+ *
+ * On input, r does not need to be initialized. a must be a valid field element with
+ * magnitude not exceeding m. m must be an integer constant expression in [0,31].
+ * Performs {r = -a}.
+ * On output, r will not be normalized, and will have magnitude m+1.
+ */
+#define secp256k1_fe_negate(r, a, m) ASSERT_INT_CONST_AND_DO(m, secp256k1_fe_negate_unchecked(r, a, m))
 
-/** Multiplies the passed field element with a small integer constant. Multiplies the magnitude by that
- *  small integer. */
-static void secp256k1_fe_mul_int(secp256k1_fe *r, int a);
+/** Like secp256k1_fe_negate_unchecked but m is not checked to be an integer constant expression.
+ *
+ * Should not be called directly outside of tests.
+ */
+static void secp256k1_fe_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m);
 
-/** Adds a field element to another. The result has the sum of the inputs' magnitudes as magnitude. */
+/** Add a small integer to a field element.
+ *
+ * Performs {r += a}. The magnitude of r increases by 1, and normalized is cleared.
+ * a must be in range [0,0x7FFF].
+ */
+static void secp256k1_fe_add_int(secp256k1_fe *r, int a);
+
+/** Multiply a field element with a small integer.
+ *
+ * On input, r must be a valid field element. a must be an integer constant expression in [0,32].
+ * The magnitude of r times a must not exceed 32.
+ * Performs {r *= a}.
+ * On output, r's magnitude is multiplied by a, and r will not be normalized.
+ */
+#define secp256k1_fe_mul_int(r, a) ASSERT_INT_CONST_AND_DO(a, secp256k1_fe_mul_int_unchecked(r, a))
+
+/** Like secp256k1_fe_mul_int but a is not checked to be an integer constant expression.
+ * 
+ * Should not be called directly outside of tests.
+ */
+static void secp256k1_fe_mul_int_unchecked(secp256k1_fe *r, int a);
+
+/** Increment a field element by another.
+ *
+ * On input, r and a must be valid field elements, not necessarily normalized.
+ * The sum of their magnitudes must not exceed 32.
+ * Performs {r += a}.
+ * On output, r will not be normalized, and will have magnitude incremented by a's.
+ */
 static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a);
 
-/** Sets a field element to be the product of two others. Requires the inputs' magnitudes to be at most 8.
- *  The output magnitude is 1 (but not guaranteed to be normalized). */
+/** Multiply two field elements.
+ *
+ * On input, a and b must be valid field elements; r does not need to be initialized.
+ * r and a may point to the same object, but neither can be equal to b. The magnitudes
+ * of a and b must not exceed 8.
+ * Performs {r = a * b}
+ * On output, r will have magnitude 1, but won't be normalized.
+ */
 static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b);
 
-/** Sets a field element to be the square of another. Requires the input's magnitude to be at most 8.
- *  The output magnitude is 1 (but not guaranteed to be normalized). */
+/** Square a field element.
+ *
+ * On input, a must be a valid field element; r does not need to be initialized. The magnitude
+ * of a must not exceed 8.
+ * Performs {r = a**2}
+ * On output, r will have magnitude 1, but won't be normalized.
+ */
 static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a);
 
-/** If a has a square root, it is computed in r and 1 is returned. If a does not
- *  have a square root, the root of its negation is computed and 0 is returned.
- *  The input's magnitude can be at most 8. The output magnitude is 1 (but not
- *  guaranteed to be normalized). The result in r will always be a square
- *  itself. */
-static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a);
+/** Compute a square root of a field element.
+ *
+ * On input, a must be a valid field element with magnitude<=8; r need not be initialized.
+ * If sqrt(a) exists, performs {r = sqrt(a)} and returns 1.
+ * Otherwise, sqrt(-a) exists. The function performs {r = sqrt(-a)} and returns 0.
+ * The resulting value represented by r will be a square itself.
+ * Variables r and a must not point to the same object.
+ * On output, r will have magnitude 1 but will not be normalized.
+ */
+static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k1_fe * SECP256K1_RESTRICT a);
 
-/** Sets a field element to be the (modular) inverse of another. Requires the input's magnitude to be
- *  at most 8. The output magnitude is 1 (but not guaranteed to be normalized). */
+/** Compute the modular inverse of a field element.
+ *
+ * On input, a must be a valid field element; r need not be initialized.
+ * Performs {r = a**(p-2)} (which maps 0 to 0, and every other element to its
+ * inverse).
+ * On output, r will have magnitude (a.magnitude != 0) and be normalized.
+ */
 static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *a);
 
-/** Potentially faster version of secp256k1_fe_inv, without constant-time guarantee. */
+/** Compute the modular inverse of a field element, without constant-time guarantee.
+ *
+ * Behaves identically to secp256k1_fe_inv, but is not constant-time in a.
+ */
 static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a);
 
-/** Convert a field element to the storage type. */
+/** Convert a field element to secp256k1_fe_storage.
+ *
+ * On input, a must be a valid normalized field element.
+ * Performs {r = a}.
+ */
 static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a);
 
-/** Convert a field element back from the storage type. */
+/** Convert a field element back from secp256k1_fe_storage.
+ *
+ * On input, r need not be initialized.
+ * Performs {r = a}.
+ * On output, r will be normalized and will have magnitude 1.
+ */
 static void secp256k1_fe_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a);
 
 /** If flag is true, set *r equal to *a; otherwise leave it. Constant-time.  Both *r and *a must be initialized.*/
 static void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r, const secp256k1_fe_storage *a, int flag);
 
-/** If flag is true, set *r equal to *a; otherwise leave it. Constant-time.  Both *r and *a must be initialized.*/
+/** Conditionally move a field element in constant time.
+ *
+ * On input, both r and a must be valid field elements. Flag must be 0 or 1.
+ * Performs {r = flag ? a : r}.
+ *
+ * On output, r's magnitude will be the maximum of both input magnitudes.
+ * It will be normalized if and only if both inputs were normalized.
+ */
 static void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag);
 
-/** Halves the value of a field element modulo the field prime. Constant-time.
- *  For an input magnitude 'm', the output magnitude is set to 'floor(m/2) + 1'.
- *  The output is not guaranteed to be normalized, regardless of the input. */
+/** Halve the value of a field element modulo the field prime in constant-time.
+ *
+ * On input, r must be a valid field element.
+ * On output, r will be normalized and have magnitude floor(m/2) + 1 where m is
+ * the magnitude of r on input.
+ */
 static void secp256k1_fe_half(secp256k1_fe *r);
 
-/** Sets each limb of 'r' to its upper bound at magnitude 'm'. The output will also have its
- *  magnitude set to 'm' and is normalized if (and only if) 'm' is zero. */
+/** Sets r to a field element with magnitude m, normalized if (and only if) m==0.
+ *  The value is chosen so that it is likely to trigger edge cases related to
+ *  internal overflows. */
 static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m);
 
+/** Determine whether a is a square (modulo p).
+ *
+ * On input, a must be a valid field element.
+ */
+static int secp256k1_fe_is_square_var(const secp256k1_fe *a);
+
+/** Check invariants on a field element (no-op unless VERIFY is enabled). */
+static void secp256k1_fe_verify(const secp256k1_fe *a);
+#define SECP256K1_FE_VERIFY(a) secp256k1_fe_verify(a)
+
+/** Check that magnitude of a is at most m (no-op unless VERIFY is enabled). */
+static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m);
+#define SECP256K1_FE_VERIFY_MAGNITUDE(a, m) secp256k1_fe_verify_magnitude(a, m)
+
 #endif /* SECP256K1_FIELD_H */

src/field_10x26.h

@@ -9,15 +9,28 @@
 
 #include <stdint.h>
 
+/** This field implementation represents the value as 10 uint32_t limbs in base
+ *  2^26. */
 typedef struct {
-    /* X = sum(i=0..9, n[i]*2^(i*26)) mod p
-     * where p = 2^256 - 0x1000003D1
-     */
+   /* A field element f represents the sum(i=0..9, f.n[i] << (i*26)) mod p,
+    * where p is the field modulus, 2^256 - 2^32 - 977.
+    *
+    * The individual limbs f.n[i] can exceed 2^26; the field's magnitude roughly
+    * corresponds to how much excess is allowed. The value
+    * sum(i=0..9, f.n[i] << (i*26)) may exceed p, unless the field element is
+    * normalized. */
     uint32_t n[10];
-#ifdef VERIFY
-    int magnitude;
-    int normalized;
-#endif
+    /*
+     * Magnitude m requires:
+     *     n[i] <= 2 * m * (2^26 - 1) for i=0..8
+     *     n[9] <= 2 * m * (2^22 - 1)
+     *
+     * Normalized requires:
+     *     n[i] <= (2^26 - 1) for i=0..8
+     *     sum(i=0..9, n[i] << (i*26)) < p
+     *     (together these imply n[9] <= 2^22 - 1)
+     */
+    SECP256K1_FE_VERIFY_FIELDS
 } secp256k1_fe;
 
 /* Unpacks a constant into a overlapping multi-limbed FE element. */
@@ -34,12 +47,6 @@ typedef struct {
     (((uint32_t)d7) >> 10) \
 }
 
-#ifdef VERIFY
-#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0)), 1, 1}
-#else
-#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0))}
-#endif
-
 typedef struct {
     uint32_t n[8];
 } secp256k1_fe_storage;

src/field_10x26_impl.h

@@ -7,51 +7,37 @@
 #ifndef SECP256K1_FIELD_REPR_IMPL_H
 #define SECP256K1_FIELD_REPR_IMPL_H
 
+#include "checkmem.h"
 #include "util.h"
 #include "field.h"
 #include "modinv32_impl.h"
 
-/** See the comment at the top of field_5x52_impl.h for more details.
- *
- *  Here, we represent field elements as 10 uint32_t's in base 2^26, least significant first,
- *  where limbs can contain >26 bits.
- *  A magnitude M means:
- *  - 2*M*(2^22-1) is the max (inclusive) of the most significant limb
- *  - 2*M*(2^26-1) is the max (inclusive) of the remaining limbs
- */
-
 #ifdef VERIFY
-static void secp256k1_fe_verify(const secp256k1_fe *a) {
+static void secp256k1_fe_impl_verify(const secp256k1_fe *a) {
     const uint32_t *d = a->n;
-    int m = a->normalized ? 1 : 2 * a->magnitude, r = 1;
-    r &= (d[0] <= 0x3FFFFFFUL * m);
-    r &= (d[1] <= 0x3FFFFFFUL * m);
-    r &= (d[2] <= 0x3FFFFFFUL * m);
-    r &= (d[3] <= 0x3FFFFFFUL * m);
-    r &= (d[4] <= 0x3FFFFFFUL * m);
-    r &= (d[5] <= 0x3FFFFFFUL * m);
-    r &= (d[6] <= 0x3FFFFFFUL * m);
-    r &= (d[7] <= 0x3FFFFFFUL * m);
-    r &= (d[8] <= 0x3FFFFFFUL * m);
-    r &= (d[9] <= 0x03FFFFFUL * m);
-    r &= (a->magnitude >= 0);
-    r &= (a->magnitude <= 32);
+    int m = a->normalized ? 1 : 2 * a->magnitude;
+    VERIFY_CHECK(d[0] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[1] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[2] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[3] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[4] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[5] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[6] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[7] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[8] <= 0x3FFFFFFUL * m);
+    VERIFY_CHECK(d[9] <= 0x03FFFFFUL * m);
     if (a->normalized) {
-        r &= (a->magnitude <= 1);
-        if (r && (d[9] == 0x03FFFFFUL)) {
+        if (d[9] == 0x03FFFFFUL) {
             uint32_t mid = d[8] & d[7] & d[6] & d[5] & d[4] & d[3] & d[2];
             if (mid == 0x3FFFFFFUL) {
-                r &= ((d[1] + 0x40UL + ((d[0] + 0x3D1UL) >> 26)) <= 0x3FFFFFFUL);
+                VERIFY_CHECK((d[1] + 0x40UL + ((d[0] + 0x3D1UL) >> 26)) <= 0x3FFFFFFUL);
             }
         }
     }
-    VERIFY_CHECK(r == 1);
 }
 #endif
 
-static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
-    VERIFY_CHECK(m >= 0);
-    VERIFY_CHECK(m <= 2048);
+static void secp256k1_fe_impl_get_bounds(secp256k1_fe *r, int m) {
     r->n[0] = 0x3FFFFFFUL * 2 * m;
     r->n[1] = 0x3FFFFFFUL * 2 * m;
     r->n[2] = 0x3FFFFFFUL * 2 * m;
@@ -62,14 +48,9 @@ static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
     r->n[7] = 0x3FFFFFFUL * 2 * m;
     r->n[8] = 0x3FFFFFFUL * 2 * m;
     r->n[9] = 0x03FFFFFUL * 2 * m;
-#ifdef VERIFY
-    r->magnitude = m;
-    r->normalized = (m == 0);
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
@@ -116,15 +97,9 @@ static void secp256k1_fe_normalize(secp256k1_fe *r) {
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
     r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
@@ -148,14 +123,9 @@ static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
     r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize_var(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize_var(secp256k1_fe *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
@@ -203,15 +173,9 @@ static void secp256k1_fe_normalize_var(secp256k1_fe *r) {
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
     r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r) {
+static int secp256k1_fe_impl_normalizes_to_zero(const secp256k1_fe *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
 
@@ -240,7 +204,7 @@ static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r) {
     return (z0 == 0) | (z1 == 0x3FFFFFFUL);
 }
 
-static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
+static int secp256k1_fe_impl_normalizes_to_zero_var(const secp256k1_fe *r) {
     uint32_t t0, t1, t2, t3, t4, t5, t6, t7, t8, t9;
     uint32_t z0, z1;
     uint32_t x;
@@ -292,53 +256,29 @@ static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
     return (z0 == 0) | (z1 == 0x3FFFFFFUL);
 }
 
-SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe *r, int a) {
-    VERIFY_CHECK(0 <= a && a <= 0x7FFF);
+SECP256K1_INLINE static void secp256k1_fe_impl_set_int(secp256k1_fe *r, int a) {
     r->n[0] = a;
     r->n[1] = r->n[2] = r->n[3] = r->n[4] = r->n[5] = r->n[6] = r->n[7] = r->n[8] = r->n[9] = 0;
-#ifdef VERIFY
-    r->magnitude = (a != 0);
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe *a) {
+SECP256K1_INLINE static int secp256k1_fe_impl_is_zero(const secp256k1_fe *a) {
     const uint32_t *t = a->n;
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
     return (t[0] | t[1] | t[2] | t[3] | t[4] | t[5] | t[6] | t[7] | t[8] | t[9]) == 0;
 }
 
-SECP256K1_INLINE static int secp256k1_fe_is_odd(const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static int secp256k1_fe_impl_is_odd(const secp256k1_fe *a) {
     return a->n[0] & 1;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe *a) {
+SECP256K1_INLINE static void secp256k1_fe_impl_clear(secp256k1_fe *a) {
     int i;
-#ifdef VERIFY
-    a->magnitude = 0;
-    a->normalized = 1;
-#endif
     for (i=0; i<10; i++) {
         a->n[i] = 0;
     }
 }
 
-static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
+static int secp256k1_fe_impl_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     int i;
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    VERIFY_CHECK(b->normalized);
-    secp256k1_fe_verify(a);
-    secp256k1_fe_verify(b);
-#endif
     for (i = 9; i >= 0; i--) {
         if (a->n[i] > b->n[i]) {
             return 1;
@@ -350,8 +290,7 @@ static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     return 0;
 }
 
-static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a) {
-    int ret;
+static void secp256k1_fe_impl_set_b32_mod(secp256k1_fe *r, const unsigned char *a) {
     r->n[0] = (uint32_t)a[31] | ((uint32_t)a[30] << 8) | ((uint32_t)a[29] << 16) | ((uint32_t)(a[28] & 0x3) << 24);
     r->n[1] = (uint32_t)((a[28] >> 2) & 0x3f) | ((uint32_t)a[27] << 6) | ((uint32_t)a[26] << 14) | ((uint32_t)(a[25] & 0xf) << 22);
     r->n[2] = (uint32_t)((a[25] >> 4) & 0xf) | ((uint32_t)a[24] << 4) | ((uint32_t)a[23] << 12) | ((uint32_t)(a[22] & 0x3f) << 20);
@@ -362,26 +301,15 @@ static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a) {
     r->n[7] = (uint32_t)((a[9] >> 6) & 0x3) | ((uint32_t)a[8] << 2) | ((uint32_t)a[7] << 10) | ((uint32_t)a[6] << 18);
     r->n[8] = (uint32_t)a[5] | ((uint32_t)a[4] << 8) | ((uint32_t)a[3] << 16) | ((uint32_t)(a[2] & 0x3) << 24);
     r->n[9] = (uint32_t)((a[2] >> 2) & 0x3f) | ((uint32_t)a[1] << 6) | ((uint32_t)a[0] << 14);
+}
 
-    ret = !((r->n[9] == 0x3FFFFFUL) & ((r->n[8] & r->n[7] & r->n[6] & r->n[5] & r->n[4] & r->n[3] & r->n[2]) == 0x3FFFFFFUL) & ((r->n[1] + 0x40UL + ((r->n[0] + 0x3D1UL) >> 26)) > 0x3FFFFFFUL));
-#ifdef VERIFY
-    r->magnitude = 1;
-    if (ret) {
-        r->normalized = 1;
-        secp256k1_fe_verify(r);
-    } else {
-        r->normalized = 0;
-    }
-#endif
-    return ret;
+static int secp256k1_fe_impl_set_b32_limit(secp256k1_fe *r, const unsigned char *a) {
+    secp256k1_fe_impl_set_b32_mod(r, a);
+    return !((r->n[9] == 0x3FFFFFUL) & ((r->n[8] & r->n[7] & r->n[6] & r->n[5] & r->n[4] & r->n[3] & r->n[2]) == 0x3FFFFFFUL) & ((r->n[1] + 0x40UL + ((r->n[0] + 0x3D1UL) >> 26)) > 0x3FFFFFFUL));
 }
 
 /** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */
-static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
+static void secp256k1_fe_impl_get_b32(unsigned char *r, const secp256k1_fe *a) {
     r[0] = (a->n[9] >> 14) & 0xff;
     r[1] = (a->n[9] >> 6) & 0xff;
     r[2] = ((a->n[9] & 0x3F) << 2) | ((a->n[8] >> 24) & 0x3);
@@ -416,15 +344,15 @@ static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a) {
     r[31] = a->n[0] & 0xff;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k1_fe *a, int m) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= m);
-    secp256k1_fe_verify(a);
+SECP256K1_INLINE static void secp256k1_fe_impl_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m) {
+    /* For all legal values of m (0..31), the following properties hold: */
     VERIFY_CHECK(0x3FFFC2FUL * 2 * (m + 1) >= 0x3FFFFFFUL * 2 * m);
     VERIFY_CHECK(0x3FFFFBFUL * 2 * (m + 1) >= 0x3FFFFFFUL * 2 * m);
     VERIFY_CHECK(0x3FFFFFFUL * 2 * (m + 1) >= 0x3FFFFFFUL * 2 * m);
     VERIFY_CHECK(0x03FFFFFUL * 2 * (m + 1) >= 0x03FFFFFUL * 2 * m);
-#endif
+
+    /* Due to the properties above, the left hand in the subtractions below is never less than
+     * the right hand. */
     r->n[0] = 0x3FFFC2FUL * 2 * (m + 1) - a->n[0];
     r->n[1] = 0x3FFFFBFUL * 2 * (m + 1) - a->n[1];
     r->n[2] = 0x3FFFFFFUL * 2 * (m + 1) - a->n[2];
@@ -435,14 +363,9 @@ SECP256K1_INLINE static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k
     r->n[7] = 0x3FFFFFFUL * 2 * (m + 1) - a->n[7];
     r->n[8] = 0x3FFFFFFUL * 2 * (m + 1) - a->n[8];
     r->n[9] = 0x03FFFFFUL * 2 * (m + 1) - a->n[9];
-#ifdef VERIFY
-    r->magnitude = m + 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static void secp256k1_fe_mul_int(secp256k1_fe *r, int a) {
+SECP256K1_INLINE static void secp256k1_fe_impl_mul_int_unchecked(secp256k1_fe *r, int a) {
     r->n[0] *= a;
     r->n[1] *= a;
     r->n[2] *= a;
@@ -453,17 +376,9 @@ SECP256K1_INLINE static void secp256k1_fe_mul_int(secp256k1_fe *r, int a) {
     r->n[7] *= a;
     r->n[8] *= a;
     r->n[9] *= a;
-#ifdef VERIFY
-    r->magnitude *= a;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_add(secp256k1_fe *r, const secp256k1_fe *a) {
     r->n[0] += a->n[0];
     r->n[1] += a->n[1];
     r->n[2] += a->n[2];
@@ -474,11 +389,10 @@ SECP256K1_INLINE static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_f
     r->n[7] += a->n[7];
     r->n[8] += a->n[8];
     r->n[9] += a->n[9];
-#ifdef VERIFY
-    r->magnitude += a->magnitude;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
+}
+
+SECP256K1_INLINE static void secp256k1_fe_impl_add_int(secp256k1_fe *r, int a) {
+    r->n[0] += a;
 }
 
 #if defined(USE_EXTERNAL_ASM)
@@ -489,11 +403,7 @@ void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t *a);
 
 #else
 
-#ifdef VERIFY
 #define VERIFY_BITS(x, n) VERIFY_CHECK(((x) >> (n)) == 0)
-#else
-#define VERIFY_BITS(x, n) do { } while(0)
-#endif
 
 SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint32_t *r, const uint32_t *a, const uint32_t * SECP256K1_RESTRICT b) {
     uint64_t c, d;
@@ -1100,40 +1010,19 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint32_t *r, const uint32_t
 }
 #endif
 
-static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    VERIFY_CHECK(b->magnitude <= 8);
-    secp256k1_fe_verify(a);
-    secp256k1_fe_verify(b);
-    VERIFY_CHECK(r != b);
-    VERIFY_CHECK(a != b);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) {
     secp256k1_fe_mul_inner(r->n, a->n, b->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
     secp256k1_fe_sqr_inner(r->n, a->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static SECP256K1_INLINE void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {
+SECP256K1_INLINE static void secp256k1_fe_impl_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {
     uint32_t mask0, mask1;
-    VG_CHECK_VERIFY(r->n, sizeof(r->n));
-    mask0 = flag + ~((uint32_t)0);
+    volatile int vflag = flag;
+    SECP256K1_CHECKMEM_CHECK_VERIFY(r->n, sizeof(r->n));
+    mask0 = vflag + ~((uint32_t)0);
     mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
     r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
@@ -1145,25 +1034,14 @@ static SECP256K1_INLINE void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_
     r->n[7] = (r->n[7] & mask0) | (a->n[7] & mask1);
     r->n[8] = (r->n[8] & mask0) | (a->n[8] & mask1);
     r->n[9] = (r->n[9] & mask0) | (a->n[9] & mask1);
-#ifdef VERIFY
-    if (flag) {
-        r->magnitude = a->magnitude;
-        r->normalized = a->normalized;
-    }
-#endif
 }
 
-static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
+static SECP256K1_INLINE void secp256k1_fe_impl_half(secp256k1_fe *r) {
     uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
              t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];
     uint32_t one = (uint32_t)1;
     uint32_t mask = -(t0 & one) >> 6;
 
-#ifdef VERIFY
-    secp256k1_fe_verify(r);
-    VERIFY_CHECK(r->magnitude < 32);
-#endif
-
     /* Bounds analysis (over the rationals).
      *
      * Let m = r->magnitude
@@ -1210,10 +1088,8 @@ static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
      *
      * Current bounds: t0..t8 <= C * (m/2 + 1/2)
      *                     t9 <= D * (m/2 + 1/4)
-     */
-
-#ifdef VERIFY
-    /* Therefore the output magnitude (M) has to be set such that:
+     *
+     * Therefore the output magnitude (M) has to be set such that:
      *     t0..t8: C * M >= C * (m/2 + 1/2)
      *         t9: D * M >= D * (m/2 + 1/4)
      *
@@ -1223,16 +1099,13 @@ static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
      * and since we want the smallest such integer value for M:
      *     M == floor(m/2) + 1
      */
-    r->magnitude = (r->magnitude >> 1) + 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static SECP256K1_INLINE void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r, const secp256k1_fe_storage *a, int flag) {
     uint32_t mask0, mask1;
-    VG_CHECK_VERIFY(r->n, sizeof(r->n));
-    mask0 = flag + ~((uint32_t)0);
+    volatile int vflag = flag;
+    SECP256K1_CHECKMEM_CHECK_VERIFY(r->n, sizeof(r->n));
+    mask0 = vflag + ~((uint32_t)0);
     mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
     r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
@@ -1244,10 +1117,7 @@ static SECP256K1_INLINE void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r,
     r->n[7] = (r->n[7] & mask0) | (a->n[7] & mask1);
 }
 
-static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-#endif
+static void secp256k1_fe_impl_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a) {
     r->n[0] = a->n[0] | a->n[1] << 26;
     r->n[1] = a->n[1] >> 6 | a->n[2] << 20;
     r->n[2] = a->n[2] >> 12 | a->n[3] << 14;
@@ -1258,7 +1128,7 @@ static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe
     r->n[7] = a->n[8] >> 16 | a->n[9] << 10;
 }
 
-static SECP256K1_INLINE void secp256k1_fe_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a) {
+static SECP256K1_INLINE void secp256k1_fe_impl_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a) {
     r->n[0] = a->n[0] & 0x3FFFFFFUL;
     r->n[1] = a->n[0] >> 26 | ((a->n[1] << 6) & 0x3FFFFFFUL);
     r->n[2] = a->n[1] >> 20 | ((a->n[2] << 12) & 0x3FFFFFFUL);
@@ -1269,11 +1139,6 @@ static SECP256K1_INLINE void secp256k1_fe_from_storage(secp256k1_fe *r, const se
     r->n[7] = a->n[5] >> 22 | ((a->n[6] << 10) & 0x3FFFFFFUL);
     r->n[8] = a->n[6] >> 16 | ((a->n[7] << 16) & 0x3FFFFFFUL);
     r->n[9] = a->n[7] >> 10;
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static void secp256k1_fe_from_signed30(secp256k1_fe *r, const secp256k1_modinv32_signed30 *a) {
@@ -1304,12 +1169,6 @@ static void secp256k1_fe_from_signed30(secp256k1_fe *r, const secp256k1_modinv32
     r->n[7] = (a6 >>  2           ) & M26;
     r->n[8] = (a6 >> 28 | a7 <<  2) & M26;
     r->n[9] = (a7 >> 24 | a8 <<  6);
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static void secp256k1_fe_to_signed30(secp256k1_modinv32_signed30 *r, const secp256k1_fe *a) {
@@ -1317,10 +1176,6 @@ static void secp256k1_fe_to_signed30(secp256k1_modinv32_signed30 *r, const secp2
     const uint64_t a0 = a->n[0], a1 = a->n[1], a2 = a->n[2], a3 = a->n[3], a4 = a->n[4],
                    a5 = a->n[5], a6 = a->n[6], a7 = a->n[7], a8 = a->n[8], a9 = a->n[9];
 
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-#endif
-
     r->v[0] = (a0       | a1 << 26) & M30;
     r->v[1] = (a1 >>  4 | a2 << 22) & M30;
     r->v[2] = (a2 >>  8 | a3 << 18) & M30;
@@ -1338,30 +1193,47 @@ static const secp256k1_modinv32_modinfo secp256k1_const_modinfo_fe = {
     0x2DDACACFL
 };
 
-static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *x) {
-    secp256k1_fe tmp;
+static void secp256k1_fe_impl_inv(secp256k1_fe *r, const secp256k1_fe *x) {
+    secp256k1_fe tmp = *x;
     secp256k1_modinv32_signed30 s;
 
-    tmp = *x;
     secp256k1_fe_normalize(&tmp);
     secp256k1_fe_to_signed30(&s, &tmp);
     secp256k1_modinv32(&s, &secp256k1_const_modinfo_fe);
     secp256k1_fe_from_signed30(r, &s);
-
-    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
 }
 
-static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
-    secp256k1_fe tmp;
+static void secp256k1_fe_impl_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
+    secp256k1_fe tmp = *x;
     secp256k1_modinv32_signed30 s;
 
-    tmp = *x;
     secp256k1_fe_normalize_var(&tmp);
     secp256k1_fe_to_signed30(&s, &tmp);
     secp256k1_modinv32_var(&s, &secp256k1_const_modinfo_fe);
     secp256k1_fe_from_signed30(r, &s);
+}
 
-    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
+static int secp256k1_fe_impl_is_square_var(const secp256k1_fe *x) {
+    secp256k1_fe tmp;
+    secp256k1_modinv32_signed30 s;
+    int jac, ret;
+
+    tmp = *x;
+    secp256k1_fe_normalize_var(&tmp);
+    /* secp256k1_jacobi32_maybe_var cannot deal with input 0. */
+    if (secp256k1_fe_is_zero(&tmp)) return 1;
+    secp256k1_fe_to_signed30(&s, &tmp);
+    jac = secp256k1_jacobi32_maybe_var(&s, &secp256k1_const_modinfo_fe);
+    if (jac == 0) {
+        /* secp256k1_jacobi32_maybe_var failed to compute the Jacobi symbol. Fall back
+         * to computing a square root. This should be extremely rare with random
+         * input (except in VERIFY mode, where a lower iteration count is used). */
+        secp256k1_fe dummy;
+        ret = secp256k1_fe_sqrt(&dummy, &tmp);
+    } else {
+        ret = jac >= 0;
+    }
+    return ret;
 }
 
 #endif /* SECP256K1_FIELD_REPR_IMPL_H */

src/field_5x52.h

@@ -9,15 +9,28 @@
 
 #include <stdint.h>
 
+/** This field implementation represents the value as 5 uint64_t limbs in base
+ *  2^52. */
 typedef struct {
-    /* X = sum(i=0..4, n[i]*2^(i*52)) mod p
-     * where p = 2^256 - 0x1000003D1
-     */
+   /* A field element f represents the sum(i=0..4, f.n[i] << (i*52)) mod p,
+    * where p is the field modulus, 2^256 - 2^32 - 977.
+    *
+    * The individual limbs f.n[i] can exceed 2^52; the field's magnitude roughly
+    * corresponds to how much excess is allowed. The value
+    * sum(i=0..4, f.n[i] << (i*52)) may exceed p, unless the field element is
+    * normalized. */
     uint64_t n[5];
-#ifdef VERIFY
-    int magnitude;
-    int normalized;
-#endif
+    /*
+     * Magnitude m requires:
+     *     n[i] <= 2 * m * (2^52 - 1) for i=0..3
+     *     n[4] <= 2 * m * (2^48 - 1)
+     *
+     * Normalized requires:
+     *     n[i] <= (2^52 - 1) for i=0..3
+     *     sum(i=0..4, n[i] << (i*52)) < p
+     *     (together these imply n[4] <= 2^48 - 1)
+     */
+    SECP256K1_FE_VERIFY_FIELDS
 } secp256k1_fe;
 
 /* Unpacks a constant into a overlapping multi-limbed FE element. */
@@ -29,12 +42,6 @@ typedef struct {
     ((uint64_t)(d6) >> 16) | (((uint64_t)(d7)) << 16) \
 }
 
-#ifdef VERIFY
-#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0)), 1, 1}
-#else
-#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0))}
-#endif
-
 typedef struct {
     uint64_t n[4];
 } secp256k1_fe_storage;

src/field_5x52_asm_impl.h

@@ -1,502 +0,0 @@
-/***********************************************************************
- * Copyright (c) 2013-2014 Diederik Huys, Pieter Wuille                *
- * Distributed under the MIT software license, see the accompanying    *
- * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
- ***********************************************************************/
-
-/**
- * Changelog:
- * - March 2013, Diederik Huys:    original version
- * - November 2014, Pieter Wuille: updated to use Peter Dettman's parallel multiplication algorithm
- * - December 2014, Pieter Wuille: converted from YASM to GCC inline assembly
- */
-
-#ifndef SECP256K1_FIELD_INNER5X52_IMPL_H
-#define SECP256K1_FIELD_INNER5X52_IMPL_H
-
-SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t *a, const uint64_t * SECP256K1_RESTRICT b) {
-/**
- * Registers: rdx:rax = multiplication accumulator
- *            r9:r8   = c
- *            r15:rcx = d
- *            r10-r14 = a0-a4
- *            rbx     = b
- *            rdi     = r
- *            rsi     = a / t?
- */
-  uint64_t tmp1, tmp2, tmp3;
-__asm__ __volatile__(
-    "movq 0(%%rsi),%%r10\n"
-    "movq 8(%%rsi),%%r11\n"
-    "movq 16(%%rsi),%%r12\n"
-    "movq 24(%%rsi),%%r13\n"
-    "movq 32(%%rsi),%%r14\n"
-
-    /* d += a3 * b0 */
-    "movq 0(%%rbx),%%rax\n"
-    "mulq %%r13\n"
-    "movq %%rax,%%rcx\n"
-    "movq %%rdx,%%r15\n"
-    /* d += a2 * b1 */
-    "movq 8(%%rbx),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a1 * b2 */
-    "movq 16(%%rbx),%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d = a0 * b3 */
-    "movq 24(%%rbx),%%rax\n"
-    "mulq %%r10\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* c = a4 * b4 */
-    "movq 32(%%rbx),%%rax\n"
-    "mulq %%r14\n"
-    "movq %%rax,%%r8\n"
-    "movq %%rdx,%%r9\n"
-    /* d += (c & M) * R */
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* c >>= 52 (%%r8 only) */
-    "shrdq $52,%%r9,%%r8\n"
-    /* t3 (tmp1) = d & M */
-    "movq %%rcx,%%rsi\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rsi\n"
-    "movq %%rsi,%q1\n"
-    /* d >>= 52 */
-    "shrdq $52,%%r15,%%rcx\n"
-    "xorq %%r15,%%r15\n"
-    /* d += a4 * b0 */
-    "movq 0(%%rbx),%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a3 * b1 */
-    "movq 8(%%rbx),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a2 * b2 */
-    "movq 16(%%rbx),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a1 * b3 */
-    "movq 24(%%rbx),%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a0 * b4 */
-    "movq 32(%%rbx),%%rax\n"
-    "mulq %%r10\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += c * R */
-    "movq %%r8,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* t4 = d & M (%%rsi) */
-    "movq %%rcx,%%rsi\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rsi\n"
-    /* d >>= 52 */
-    "shrdq $52,%%r15,%%rcx\n"
-    "xorq %%r15,%%r15\n"
-    /* tx = t4 >> 48 (tmp3) */
-    "movq %%rsi,%%rax\n"
-    "shrq $48,%%rax\n"
-    "movq %%rax,%q3\n"
-    /* t4 &= (M >> 4) (tmp2) */
-    "movq $0xffffffffffff,%%rax\n"
-    "andq %%rax,%%rsi\n"
-    "movq %%rsi,%q2\n"
-    /* c = a0 * b0 */
-    "movq 0(%%rbx),%%rax\n"
-    "mulq %%r10\n"
-    "movq %%rax,%%r8\n"
-    "movq %%rdx,%%r9\n"
-    /* d += a4 * b1 */
-    "movq 8(%%rbx),%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a3 * b2 */
-    "movq 16(%%rbx),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a2 * b3 */
-    "movq 24(%%rbx),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a1 * b4 */
-    "movq 32(%%rbx),%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* u0 = d & M (%%rsi) */
-    "movq %%rcx,%%rsi\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rsi\n"
-    /* d >>= 52 */
-    "shrdq $52,%%r15,%%rcx\n"
-    "xorq %%r15,%%r15\n"
-    /* u0 = (u0 << 4) | tx (%%rsi) */
-    "shlq $4,%%rsi\n"
-    "movq %q3,%%rax\n"
-    "orq %%rax,%%rsi\n"
-    /* c += u0 * (R >> 4) */
-    "movq $0x1000003d1,%%rax\n"
-    "mulq %%rsi\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* r[0] = c & M */
-    "movq %%r8,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq %%rax,0(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* c += a1 * b0 */
-    "movq 0(%%rbx),%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* c += a0 * b1 */
-    "movq 8(%%rbx),%%rax\n"
-    "mulq %%r10\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d += a4 * b2 */
-    "movq 16(%%rbx),%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a3 * b3 */
-    "movq 24(%%rbx),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a2 * b4 */
-    "movq 32(%%rbx),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* c += (d & M) * R */
-    "movq %%rcx,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d >>= 52 */
-    "shrdq $52,%%r15,%%rcx\n"
-    "xorq %%r15,%%r15\n"
-    /* r[1] = c & M */
-    "movq %%r8,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq %%rax,8(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* c += a2 * b0 */
-    "movq 0(%%rbx),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* c += a1 * b1 */
-    "movq 8(%%rbx),%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* c += a0 * b2 (last use of %%r10 = a0) */
-    "movq 16(%%rbx),%%rax\n"
-    "mulq %%r10\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* fetch t3 (%%r10, overwrites a0), t4 (%%rsi) */
-    "movq %q2,%%rsi\n"
-    "movq %q1,%%r10\n"
-    /* d += a4 * b3 */
-    "movq 24(%%rbx),%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* d += a3 * b4 */
-    "movq 32(%%rbx),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rcx\n"
-    "adcq %%rdx,%%r15\n"
-    /* c += (d & M) * R */
-    "movq %%rcx,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d >>= 52 (%%rcx only) */
-    "shrdq $52,%%r15,%%rcx\n"
-    /* r[2] = c & M */
-    "movq %%r8,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq %%rax,16(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* c += t3 */
-    "addq %%r10,%%r8\n"
-    /* c += d * R */
-    "movq %%rcx,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* r[3] = c & M */
-    "movq %%r8,%%rax\n"
-    "movq $0xfffffffffffff,%%rdx\n"
-    "andq %%rdx,%%rax\n"
-    "movq %%rax,24(%%rdi)\n"
-    /* c >>= 52 (%%r8 only) */
-    "shrdq $52,%%r9,%%r8\n"
-    /* c += t4 (%%r8 only) */
-    "addq %%rsi,%%r8\n"
-    /* r[4] = c */
-    "movq %%r8,32(%%rdi)\n"
-: "+S"(a), "=m"(tmp1), "=m"(tmp2), "=m"(tmp3)
-: "b"(b), "D"(r)
-: "%rax", "%rcx", "%rdx", "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15", "cc", "memory"
-);
-}
-
-SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t *a) {
-/**
- * Registers: rdx:rax = multiplication accumulator
- *            r9:r8   = c
- *            rcx:rbx = d
- *            r10-r14 = a0-a4
- *            r15     = M (0xfffffffffffff)
- *            rdi     = r
- *            rsi     = a / t?
- */
-  uint64_t tmp1, tmp2, tmp3;
-__asm__ __volatile__(
-    "movq 0(%%rsi),%%r10\n"
-    "movq 8(%%rsi),%%r11\n"
-    "movq 16(%%rsi),%%r12\n"
-    "movq 24(%%rsi),%%r13\n"
-    "movq 32(%%rsi),%%r14\n"
-    "movq $0xfffffffffffff,%%r15\n"
-
-    /* d = (a0*2) * a3 */
-    "leaq (%%r10,%%r10,1),%%rax\n"
-    "mulq %%r13\n"
-    "movq %%rax,%%rbx\n"
-    "movq %%rdx,%%rcx\n"
-    /* d += (a1*2) * a2 */
-    "leaq (%%r11,%%r11,1),%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* c = a4 * a4 */
-    "movq %%r14,%%rax\n"
-    "mulq %%r14\n"
-    "movq %%rax,%%r8\n"
-    "movq %%rdx,%%r9\n"
-    /* d += (c & M) * R */
-    "andq %%r15,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* c >>= 52 (%%r8 only) */
-    "shrdq $52,%%r9,%%r8\n"
-    /* t3 (tmp1) = d & M */
-    "movq %%rbx,%%rsi\n"
-    "andq %%r15,%%rsi\n"
-    "movq %%rsi,%q1\n"
-    /* d >>= 52 */
-    "shrdq $52,%%rcx,%%rbx\n"
-    "xorq %%rcx,%%rcx\n"
-    /* a4 *= 2 */
-    "addq %%r14,%%r14\n"
-    /* d += a0 * a4 */
-    "movq %%r10,%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* d+= (a1*2) * a3 */
-    "leaq (%%r11,%%r11,1),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* d += a2 * a2 */
-    "movq %%r12,%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* d += c * R */
-    "movq %%r8,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* t4 = d & M (%%rsi) */
-    "movq %%rbx,%%rsi\n"
-    "andq %%r15,%%rsi\n"
-    /* d >>= 52 */
-    "shrdq $52,%%rcx,%%rbx\n"
-    "xorq %%rcx,%%rcx\n"
-    /* tx = t4 >> 48 (tmp3) */
-    "movq %%rsi,%%rax\n"
-    "shrq $48,%%rax\n"
-    "movq %%rax,%q3\n"
-    /* t4 &= (M >> 4) (tmp2) */
-    "movq $0xffffffffffff,%%rax\n"
-    "andq %%rax,%%rsi\n"
-    "movq %%rsi,%q2\n"
-    /* c = a0 * a0 */
-    "movq %%r10,%%rax\n"
-    "mulq %%r10\n"
-    "movq %%rax,%%r8\n"
-    "movq %%rdx,%%r9\n"
-    /* d += a1 * a4 */
-    "movq %%r11,%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* d += (a2*2) * a3 */
-    "leaq (%%r12,%%r12,1),%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* u0 = d & M (%%rsi) */
-    "movq %%rbx,%%rsi\n"
-    "andq %%r15,%%rsi\n"
-    /* d >>= 52 */
-    "shrdq $52,%%rcx,%%rbx\n"
-    "xorq %%rcx,%%rcx\n"
-    /* u0 = (u0 << 4) | tx (%%rsi) */
-    "shlq $4,%%rsi\n"
-    "movq %q3,%%rax\n"
-    "orq %%rax,%%rsi\n"
-    /* c += u0 * (R >> 4) */
-    "movq $0x1000003d1,%%rax\n"
-    "mulq %%rsi\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* r[0] = c & M */
-    "movq %%r8,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq %%rax,0(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* a0 *= 2 */
-    "addq %%r10,%%r10\n"
-    /* c += a0 * a1 */
-    "movq %%r10,%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d += a2 * a4 */
-    "movq %%r12,%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* d += a3 * a3 */
-    "movq %%r13,%%rax\n"
-    "mulq %%r13\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* c += (d & M) * R */
-    "movq %%rbx,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d >>= 52 */
-    "shrdq $52,%%rcx,%%rbx\n"
-    "xorq %%rcx,%%rcx\n"
-    /* r[1] = c & M */
-    "movq %%r8,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq %%rax,8(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* c += a0 * a2 (last use of %%r10) */
-    "movq %%r10,%%rax\n"
-    "mulq %%r12\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* fetch t3 (%%r10, overwrites a0),t4 (%%rsi) */
-    "movq %q2,%%rsi\n"
-    "movq %q1,%%r10\n"
-    /* c += a1 * a1 */
-    "movq %%r11,%%rax\n"
-    "mulq %%r11\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d += a3 * a4 */
-    "movq %%r13,%%rax\n"
-    "mulq %%r14\n"
-    "addq %%rax,%%rbx\n"
-    "adcq %%rdx,%%rcx\n"
-    /* c += (d & M) * R */
-    "movq %%rbx,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* d >>= 52 (%%rbx only) */
-    "shrdq $52,%%rcx,%%rbx\n"
-    /* r[2] = c & M */
-    "movq %%r8,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq %%rax,16(%%rdi)\n"
-    /* c >>= 52 */
-    "shrdq $52,%%r9,%%r8\n"
-    "xorq %%r9,%%r9\n"
-    /* c += t3 */
-    "addq %%r10,%%r8\n"
-    /* c += d * R */
-    "movq %%rbx,%%rax\n"
-    "movq $0x1000003d10,%%rdx\n"
-    "mulq %%rdx\n"
-    "addq %%rax,%%r8\n"
-    "adcq %%rdx,%%r9\n"
-    /* r[3] = c & M */
-    "movq %%r8,%%rax\n"
-    "andq %%r15,%%rax\n"
-    "movq %%rax,24(%%rdi)\n"
-    /* c >>= 52 (%%r8 only) */
-    "shrdq $52,%%r9,%%r8\n"
-    /* c += t4 (%%r8 only) */
-    "addq %%rsi,%%r8\n"
-    /* r[4] = c */
-    "movq %%r8,32(%%rdi)\n"
-: "+S"(a), "=m"(tmp1), "=m"(tmp2), "=m"(tmp3)
-: "D"(r)
-: "%rax", "%rbx", "%rcx", "%rdx", "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15", "cc", "memory"
-);
-}
-
-#endif /* SECP256K1_FIELD_INNER5X52_IMPL_H */

src/field_5x52_impl.h

@@ -7,73 +7,40 @@
 #ifndef SECP256K1_FIELD_REPR_IMPL_H
 #define SECP256K1_FIELD_REPR_IMPL_H
 
-#if defined HAVE_CONFIG_H
-#include "libsecp256k1-config.h"
-#endif
-
+#include "checkmem.h"
 #include "util.h"
 #include "field.h"
 #include "modinv64_impl.h"
 
-#if defined(USE_ASM_X86_64)
-#include "field_5x52_asm_impl.h"
-#else
 #include "field_5x52_int128_impl.h"
-#endif
-
-/** Implements arithmetic modulo FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F,
- *  represented as 5 uint64_t's in base 2^52, least significant first. Note that the limbs are allowed to
- *  contain >52 bits each.
- *
- *  Each field element has a 'magnitude' associated with it. Internally, a magnitude M means:
- *  - 2*M*(2^48-1) is the max (inclusive) of the most significant limb
- *  - 2*M*(2^52-1) is the max (inclusive) of the remaining limbs
- *
- *  Operations have different rules for propagating magnitude to their outputs. If an operation takes a
- *  magnitude M as a parameter, that means the magnitude of input field elements can be at most M (inclusive).
- *
- *  Each field element also has a 'normalized' flag. A field element is normalized if its magnitude is either
- *  0 or 1, and its value is already reduced modulo the order of the field.
- */
 
 #ifdef VERIFY
-static void secp256k1_fe_verify(const secp256k1_fe *a) {
+static void secp256k1_fe_impl_verify(const secp256k1_fe *a) {
     const uint64_t *d = a->n;
-    int m = a->normalized ? 1 : 2 * a->magnitude, r = 1;
+    int m = a->normalized ? 1 : 2 * a->magnitude;
    /* secp256k1 'p' value defined in "Standards for Efficient Cryptography" (SEC2) 2.7.1. */
-    r &= (d[0] <= 0xFFFFFFFFFFFFFULL * m);
-    r &= (d[1] <= 0xFFFFFFFFFFFFFULL * m);
-    r &= (d[2] <= 0xFFFFFFFFFFFFFULL * m);
-    r &= (d[3] <= 0xFFFFFFFFFFFFFULL * m);
-    r &= (d[4] <= 0x0FFFFFFFFFFFFULL * m);
-    r &= (a->magnitude >= 0);
-    r &= (a->magnitude <= 2048);
+    VERIFY_CHECK(d[0] <= 0xFFFFFFFFFFFFFULL * m);
+    VERIFY_CHECK(d[1] <= 0xFFFFFFFFFFFFFULL * m);
+    VERIFY_CHECK(d[2] <= 0xFFFFFFFFFFFFFULL * m);
+    VERIFY_CHECK(d[3] <= 0xFFFFFFFFFFFFFULL * m);
+    VERIFY_CHECK(d[4] <= 0x0FFFFFFFFFFFFULL * m);
     if (a->normalized) {
-        r &= (a->magnitude <= 1);
-        if (r && (d[4] == 0x0FFFFFFFFFFFFULL) && ((d[3] & d[2] & d[1]) == 0xFFFFFFFFFFFFFULL)) {
-            r &= (d[0] < 0xFFFFEFFFFFC2FULL);
+        if ((d[4] == 0x0FFFFFFFFFFFFULL) && ((d[3] & d[2] & d[1]) == 0xFFFFFFFFFFFFFULL)) {
+            VERIFY_CHECK(d[0] < 0xFFFFEFFFFFC2FULL);
         }
     }
-    VERIFY_CHECK(r == 1);
 }
 #endif
 
-static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
-    VERIFY_CHECK(m >= 0);
-    VERIFY_CHECK(m <= 2048);
+static void secp256k1_fe_impl_get_bounds(secp256k1_fe *r, int m) {
     r->n[0] = 0xFFFFFFFFFFFFFULL * 2 * m;
     r->n[1] = 0xFFFFFFFFFFFFFULL * 2 * m;
     r->n[2] = 0xFFFFFFFFFFFFFULL * 2 * m;
     r->n[3] = 0xFFFFFFFFFFFFFULL * 2 * m;
     r->n[4] = 0x0FFFFFFFFFFFFULL * 2 * m;
-#ifdef VERIFY
-    r->magnitude = m;
-    r->normalized = (m == 0);
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
@@ -108,15 +75,9 @@ static void secp256k1_fe_normalize(secp256k1_fe *r) {
     t4 &= 0x0FFFFFFFFFFFFULL;
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
@@ -133,14 +94,9 @@ static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
     VERIFY_CHECK(t4 >> 49 == 0);
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_normalize_var(secp256k1_fe *r) {
+static void secp256k1_fe_impl_normalize_var(secp256k1_fe *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* Reduce t4 at the start so there will be at most a single carry from the first pass */
@@ -176,15 +132,9 @@ static void secp256k1_fe_normalize_var(secp256k1_fe *r) {
     }
 
     r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r) {
+static int secp256k1_fe_impl_normalizes_to_zero(const secp256k1_fe *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
 
     /* z0 tracks a possible raw value of 0, z1 tracks a possible raw value of P */
@@ -207,7 +157,7 @@ static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r) {
     return (z0 == 0) | (z1 == 0xFFFFFFFFFFFFFULL);
 }
 
-static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
+static int secp256k1_fe_impl_normalizes_to_zero_var(const secp256k1_fe *r) {
     uint64_t t0, t1, t2, t3, t4;
     uint64_t z0, z1;
     uint64_t x;
@@ -248,53 +198,29 @@ static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
     return (z0 == 0) | (z1 == 0xFFFFFFFFFFFFFULL);
 }
 
-SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe *r, int a) {
-    VERIFY_CHECK(0 <= a && a <= 0x7FFF);
+SECP256K1_INLINE static void secp256k1_fe_impl_set_int(secp256k1_fe *r, int a) {
     r->n[0] = a;
     r->n[1] = r->n[2] = r->n[3] = r->n[4] = 0;
-#ifdef VERIFY
-    r->magnitude = (a != 0);
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe *a) {
+SECP256K1_INLINE static int secp256k1_fe_impl_is_zero(const secp256k1_fe *a) {
     const uint64_t *t = a->n;
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
     return (t[0] | t[1] | t[2] | t[3] | t[4]) == 0;
 }
 
-SECP256K1_INLINE static int secp256k1_fe_is_odd(const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static int secp256k1_fe_impl_is_odd(const secp256k1_fe *a) {
     return a->n[0] & 1;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe *a) {
+SECP256K1_INLINE static void secp256k1_fe_impl_clear(secp256k1_fe *a) {
     int i;
-#ifdef VERIFY
-    a->magnitude = 0;
-    a->normalized = 1;
-#endif
     for (i=0; i<5; i++) {
         a->n[i] = 0;
     }
 }
 
-static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
+static int secp256k1_fe_impl_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     int i;
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    VERIFY_CHECK(b->normalized);
-    secp256k1_fe_verify(a);
-    secp256k1_fe_verify(b);
-#endif
     for (i = 4; i >= 0; i--) {
         if (a->n[i] > b->n[i]) {
             return 1;
@@ -306,8 +232,7 @@ static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     return 0;
 }
 
-static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a) {
-    int ret;
+static void secp256k1_fe_impl_set_b32_mod(secp256k1_fe *r, const unsigned char *a) {
     r->n[0] = (uint64_t)a[31]
             | ((uint64_t)a[30] << 8)
             | ((uint64_t)a[29] << 16)
@@ -342,25 +267,15 @@ static int secp256k1_fe_set_b32(secp256k1_fe *r, const unsigned char *a) {
             | ((uint64_t)a[2] << 24)
             | ((uint64_t)a[1] << 32)
             | ((uint64_t)a[0] << 40);
-    ret = !((r->n[4] == 0x0FFFFFFFFFFFFULL) & ((r->n[3] & r->n[2] & r->n[1]) == 0xFFFFFFFFFFFFFULL) & (r->n[0] >= 0xFFFFEFFFFFC2FULL));
-#ifdef VERIFY
-    r->magnitude = 1;
-    if (ret) {
-        r->normalized = 1;
-        secp256k1_fe_verify(r);
-    } else {
-        r->normalized = 0;
-    }
-#endif
-    return ret;
+}
+
+static int secp256k1_fe_impl_set_b32_limit(secp256k1_fe *r, const unsigned char *a) {
+    secp256k1_fe_impl_set_b32_mod(r, a);
+    return !((r->n[4] == 0x0FFFFFFFFFFFFULL) & ((r->n[3] & r->n[2] & r->n[1]) == 0xFFFFFFFFFFFFFULL) & (r->n[0] >= 0xFFFFEFFFFFC2FULL));
 }
 
 /** Convert a field element to a 32-byte big endian value. Requires the input to be normalized */
-static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-    secp256k1_fe_verify(a);
-#endif
+static void secp256k1_fe_impl_get_b32(unsigned char *r, const secp256k1_fe *a) {
     r[0] = (a->n[4] >> 40) & 0xFF;
     r[1] = (a->n[4] >> 32) & 0xFF;
     r[2] = (a->n[4] >> 24) & 0xFF;
@@ -395,113 +310,67 @@ static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a) {
     r[31] = a->n[0] & 0xFF;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_negate(secp256k1_fe *r, const secp256k1_fe *a, int m) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= m);
-    secp256k1_fe_verify(a);
+SECP256K1_INLINE static void secp256k1_fe_impl_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m) {
+    /* For all legal values of m (0..31), the following properties hold: */
     VERIFY_CHECK(0xFFFFEFFFFFC2FULL * 2 * (m + 1) >= 0xFFFFFFFFFFFFFULL * 2 * m);
     VERIFY_CHECK(0xFFFFFFFFFFFFFULL * 2 * (m + 1) >= 0xFFFFFFFFFFFFFULL * 2 * m);
     VERIFY_CHECK(0x0FFFFFFFFFFFFULL * 2 * (m + 1) >= 0x0FFFFFFFFFFFFULL * 2 * m);
-#endif
+
+    /* Due to the properties above, the left hand in the subtractions below is never less than
+     * the right hand. */
     r->n[0] = 0xFFFFEFFFFFC2FULL * 2 * (m + 1) - a->n[0];
     r->n[1] = 0xFFFFFFFFFFFFFULL * 2 * (m + 1) - a->n[1];
     r->n[2] = 0xFFFFFFFFFFFFFULL * 2 * (m + 1) - a->n[2];
     r->n[3] = 0xFFFFFFFFFFFFFULL * 2 * (m + 1) - a->n[3];
     r->n[4] = 0x0FFFFFFFFFFFFULL * 2 * (m + 1) - a->n[4];
-#ifdef VERIFY
-    r->magnitude = m + 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static void secp256k1_fe_mul_int(secp256k1_fe *r, int a) {
+SECP256K1_INLINE static void secp256k1_fe_impl_mul_int_unchecked(secp256k1_fe *r, int a) {
     r->n[0] *= a;
     r->n[1] *= a;
     r->n[2] *= a;
     r->n[3] *= a;
     r->n[4] *= a;
-#ifdef VERIFY
-    r->magnitude *= a;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-SECP256K1_INLINE static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_add_int(secp256k1_fe *r, int a) {
+    r->n[0] += a;
+}
+
+SECP256K1_INLINE static void secp256k1_fe_impl_add(secp256k1_fe *r, const secp256k1_fe *a) {
     r->n[0] += a->n[0];
     r->n[1] += a->n[1];
     r->n[2] += a->n[2];
     r->n[3] += a->n[3];
     r->n[4] += a->n[4];
-#ifdef VERIFY
-    r->magnitude += a->magnitude;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    VERIFY_CHECK(b->magnitude <= 8);
-    secp256k1_fe_verify(a);
-    secp256k1_fe_verify(b);
-    VERIFY_CHECK(r != b);
-    VERIFY_CHECK(a != b);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) {
     secp256k1_fe_mul_inner(r->n, a->n, b->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->magnitude <= 8);
-    secp256k1_fe_verify(a);
-#endif
+SECP256K1_INLINE static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
     secp256k1_fe_sqr_inner(r->n, a->n);
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
-static SECP256K1_INLINE void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {
+SECP256K1_INLINE static void secp256k1_fe_impl_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {
     uint64_t mask0, mask1;
-    VG_CHECK_VERIFY(r->n, sizeof(r->n));
-    mask0 = flag + ~((uint64_t)0);
+    volatile int vflag = flag;
+    SECP256K1_CHECKMEM_CHECK_VERIFY(r->n, sizeof(r->n));
+    mask0 = vflag + ~((uint64_t)0);
     mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
     r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
     r->n[2] = (r->n[2] & mask0) | (a->n[2] & mask1);
     r->n[3] = (r->n[3] & mask0) | (a->n[3] & mask1);
     r->n[4] = (r->n[4] & mask0) | (a->n[4] & mask1);
-#ifdef VERIFY
-    if (flag) {
-        r->magnitude = a->magnitude;
-        r->normalized = a->normalized;
-    }
-#endif
 }
 
-static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
+static SECP256K1_INLINE void secp256k1_fe_impl_half(secp256k1_fe *r) {
     uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];
     uint64_t one = (uint64_t)1;
     uint64_t mask = -(t0 & one) >> 12;
 
-#ifdef VERIFY
-    secp256k1_fe_verify(r);
-    VERIFY_CHECK(r->magnitude < 32);
-#endif
-
     /* Bounds analysis (over the rationals).
      *
      * Let m = r->magnitude
@@ -538,10 +407,8 @@ static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
      *
      * Current bounds: t0..t3 <= C * (m/2 + 1/2)
      *                     t4 <= D * (m/2 + 1/4)
-     */
-
-#ifdef VERIFY
-    /* Therefore the output magnitude (M) has to be set such that:
+     *
+     * Therefore the output magnitude (M) has to be set such that:
      *     t0..t3: C * M >= C * (m/2 + 1/2)
      *         t4: D * M >= D * (m/2 + 1/4)
      *
@@ -551,16 +418,13 @@ static SECP256K1_INLINE void secp256k1_fe_half(secp256k1_fe *r) {
      * and since we want the smallest such integer value for M:
      *     M == floor(m/2) + 1
      */
-    r->magnitude = (r->magnitude >> 1) + 1;
-    r->normalized = 0;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static SECP256K1_INLINE void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r, const secp256k1_fe_storage *a, int flag) {
     uint64_t mask0, mask1;
-    VG_CHECK_VERIFY(r->n, sizeof(r->n));
-    mask0 = flag + ~((uint64_t)0);
+    volatile int vflag = flag;
+    SECP256K1_CHECKMEM_CHECK_VERIFY(r->n, sizeof(r->n));
+    mask0 = vflag + ~((uint64_t)0);
     mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
     r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
@@ -568,27 +432,19 @@ static SECP256K1_INLINE void secp256k1_fe_storage_cmov(secp256k1_fe_storage *r,
     r->n[3] = (r->n[3] & mask0) | (a->n[3] & mask1);
 }
 
-static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a) {
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-#endif
+static void secp256k1_fe_impl_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a) {
     r->n[0] = a->n[0] | a->n[1] << 52;
     r->n[1] = a->n[1] >> 12 | a->n[2] << 40;
     r->n[2] = a->n[2] >> 24 | a->n[3] << 28;
     r->n[3] = a->n[3] >> 36 | a->n[4] << 16;
 }
 
-static SECP256K1_INLINE void secp256k1_fe_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a) {
+static SECP256K1_INLINE void secp256k1_fe_impl_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a) {
     r->n[0] = a->n[0] & 0xFFFFFFFFFFFFFULL;
     r->n[1] = a->n[0] >> 52 | ((a->n[1] << 12) & 0xFFFFFFFFFFFFFULL);
     r->n[2] = a->n[1] >> 40 | ((a->n[2] << 24) & 0xFFFFFFFFFFFFFULL);
     r->n[3] = a->n[2] >> 28 | ((a->n[3] << 36) & 0xFFFFFFFFFFFFFULL);
     r->n[4] = a->n[3] >> 16;
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static void secp256k1_fe_from_signed62(secp256k1_fe *r, const secp256k1_modinv64_signed62 *a) {
@@ -609,22 +465,12 @@ static void secp256k1_fe_from_signed62(secp256k1_fe *r, const secp256k1_modinv64
     r->n[2] = (a1 >> 42 | a2 << 20) & M52;
     r->n[3] = (a2 >> 32 | a3 << 30) & M52;
     r->n[4] = (a3 >> 22 | a4 << 40);
-
-#ifdef VERIFY
-    r->magnitude = 1;
-    r->normalized = 1;
-    secp256k1_fe_verify(r);
-#endif
 }
 
 static void secp256k1_fe_to_signed62(secp256k1_modinv64_signed62 *r, const secp256k1_fe *a) {
     const uint64_t M62 = UINT64_MAX >> 2;
     const uint64_t a0 = a->n[0], a1 = a->n[1], a2 = a->n[2], a3 = a->n[3], a4 = a->n[4];
 
-#ifdef VERIFY
-    VERIFY_CHECK(a->normalized);
-#endif
-
     r->v[0] = (a0       | a1 << 52) & M62;
     r->v[1] = (a1 >> 10 | a2 << 42) & M62;
     r->v[2] = (a2 >> 20 | a3 << 32) & M62;
@@ -637,34 +483,47 @@ static const secp256k1_modinv64_modinfo secp256k1_const_modinfo_fe = {
     0x27C7F6E22DDACACFLL
 };
 
-static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *x) {
-    secp256k1_fe tmp;
+static void secp256k1_fe_impl_inv(secp256k1_fe *r, const secp256k1_fe *x) {
+    secp256k1_fe tmp = *x;
     secp256k1_modinv64_signed62 s;
 
-    tmp = *x;
     secp256k1_fe_normalize(&tmp);
     secp256k1_fe_to_signed62(&s, &tmp);
     secp256k1_modinv64(&s, &secp256k1_const_modinfo_fe);
     secp256k1_fe_from_signed62(r, &s);
-
-#ifdef VERIFY
-    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
-#endif
 }
 
-static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
-    secp256k1_fe tmp;
+static void secp256k1_fe_impl_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
+    secp256k1_fe tmp = *x;
     secp256k1_modinv64_signed62 s;
 
-    tmp = *x;
     secp256k1_fe_normalize_var(&tmp);
     secp256k1_fe_to_signed62(&s, &tmp);
     secp256k1_modinv64_var(&s, &secp256k1_const_modinfo_fe);
     secp256k1_fe_from_signed62(r, &s);
+}
 
-#ifdef VERIFY
-    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == secp256k1_fe_normalizes_to_zero(&tmp));
-#endif
+static int secp256k1_fe_impl_is_square_var(const secp256k1_fe *x) {
+    secp256k1_fe tmp;
+    secp256k1_modinv64_signed62 s;
+    int jac, ret;
+
+    tmp = *x;
+    secp256k1_fe_normalize_var(&tmp);
+    /* secp256k1_jacobi64_maybe_var cannot deal with input 0. */
+    if (secp256k1_fe_is_zero(&tmp)) return 1;
+    secp256k1_fe_to_signed62(&s, &tmp);
+    jac = secp256k1_jacobi64_maybe_var(&s, &secp256k1_const_modinfo_fe);
+    if (jac == 0) {
+        /* secp256k1_jacobi64_maybe_var failed to compute the Jacobi symbol. Fall back
+         * to computing a square root. This should be extremely rare with random
+         * input (except in VERIFY mode, where a lower iteration count is used). */
+        secp256k1_fe dummy;
+        ret = secp256k1_fe_sqrt(&dummy, &tmp);
+    } else {
+        ret = jac >= 0;
+    }
+    return ret;
 }
 
 #endif /* SECP256K1_FIELD_REPR_IMPL_H */

src/field_5x52_int128_impl.h

@@ -10,14 +10,10 @@
 #include <stdint.h>
 
 #include "int128.h"
+#include "util.h"
 
-#ifdef VERIFY
 #define VERIFY_BITS(x, n) VERIFY_CHECK(((x) >> (n)) == 0)
 #define VERIFY_BITS_128(x, n) VERIFY_CHECK(secp256k1_u128_check_bits((x), (n)))
-#else
-#define VERIFY_BITS(x, n) do { } while(0)
-#define VERIFY_BITS_128(x, n) do { } while(0)
-#endif
 
 SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t *a, const uint64_t * SECP256K1_RESTRICT b) {
     secp256k1_uint128 c, d;
@@ -88,18 +84,18 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
     secp256k1_u128_accum_mul(&d, a2, b[3]);
     secp256k1_u128_accum_mul(&d, a3, b[2]);
     secp256k1_u128_accum_mul(&d, a4, b[1]);
-    VERIFY_BITS_128(&d, 115);
+    VERIFY_BITS_128(&d, 114);
     /* [d t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
     u0 = secp256k1_u128_to_u64(&d) & M; secp256k1_u128_rshift(&d, 52);
     VERIFY_BITS(u0, 52);
-    VERIFY_BITS_128(&d, 63);
+    VERIFY_BITS_128(&d, 62);
     /* [d u0 t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
     /* [d 0 t4+(tx<<48)+(u0<<52) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
     u0 = (u0 << 4) | tx;
     VERIFY_BITS(u0, 56);
     /* [d 0 t4+(u0<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
     secp256k1_u128_accum_mul(&c, u0, R >> 4);
-    VERIFY_BITS_128(&c, 115);
+    VERIFY_BITS_128(&c, 113);
     /* [d 0 t4 t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
     r[0] = secp256k1_u128_to_u64(&c) & M; secp256k1_u128_rshift(&c, 52);
     VERIFY_BITS(r[0], 52);
@@ -158,7 +154,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
 SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t *a) {
     secp256k1_uint128 c, d;
     uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
-    int64_t t3, t4, tx, u0;
+    uint64_t t3, t4, tx, u0;
     const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
 
     VERIFY_BITS(a[0], 56);

src/field_impl.h

@@ -7,10 +7,7 @@
 #ifndef SECP256K1_FIELD_IMPL_H
 #define SECP256K1_FIELD_IMPL_H
 
-#if defined HAVE_CONFIG_H
-#include "libsecp256k1-config.h"
-#endif
-
+#include "field.h"
 #include "util.h"
 
 #if defined(SECP256K1_WIDEMUL_INT128)
@@ -23,19 +20,17 @@
 
 SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b) {
     secp256k1_fe na;
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY(b);
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, 1);
+    SECP256K1_FE_VERIFY_MAGNITUDE(b, 31);
+
     secp256k1_fe_negate(&na, a, 1);
     secp256k1_fe_add(&na, b);
     return secp256k1_fe_normalizes_to_zero(&na);
 }
 
-SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe *a, const secp256k1_fe *b) {
-    secp256k1_fe na;
-    secp256k1_fe_negate(&na, a, 1);
-    secp256k1_fe_add(&na, b);
-    return secp256k1_fe_normalizes_to_zero_var(&na);
-}
-
-static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a) {
+static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k1_fe * SECP256K1_RESTRICT a) {
     /** Given that p is congruent to 3 mod 4, we can compute the square root of
      *  a mod p as the (p+1)/4'th power of a.
      *
@@ -46,9 +41,11 @@ static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a) {
      *  itself always a square (a ** ((p+1)/4) is the square of a ** ((p+1)/8)).
      */
     secp256k1_fe x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
-    int j;
+    int j, ret;
 
     VERIFY_CHECK(r != a);
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, 8);
 
     /** The binary representation of (p + 1)/4 has 3 blocks of 1s, with lengths in
      *  { 2, 22, 223 }. Use an addition chain to calculate 2^n - 1 for each block:
@@ -132,7 +129,334 @@ static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a) {
     /* Check that a square root was actually calculated */
 
     secp256k1_fe_sqr(&t1, r);
-    return secp256k1_fe_equal(&t1, a);
+    ret = secp256k1_fe_equal(&t1, a);
+
+#ifdef VERIFY
+    if (!ret) {
+        secp256k1_fe_negate(&t1, &t1, 1);
+        secp256k1_fe_normalize_var(&t1);
+        VERIFY_CHECK(secp256k1_fe_equal(&t1, a));
+    }
+#endif
+    return ret;
 }
 
+#ifndef VERIFY
+static void secp256k1_fe_verify(const secp256k1_fe *a) { (void)a; }
+static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m) { (void)a; (void)m; }
+#else
+static void secp256k1_fe_impl_verify(const secp256k1_fe *a);
+static void secp256k1_fe_verify(const secp256k1_fe *a) {
+    /* Magnitude between 0 and 32. */
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, 32);
+    /* Normalized is 0 or 1. */
+    VERIFY_CHECK((a->normalized == 0) || (a->normalized == 1));
+    /* If normalized, magnitude must be 0 or 1. */
+    if (a->normalized) SECP256K1_FE_VERIFY_MAGNITUDE(a, 1);
+    /* Invoke implementation-specific checks. */
+    secp256k1_fe_impl_verify(a);
+}
+
+static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m) {
+    VERIFY_CHECK(m >= 0);
+    VERIFY_CHECK(m <= 32);
+    VERIFY_CHECK(a->magnitude <= m);
+}
+
+static void secp256k1_fe_impl_normalize(secp256k1_fe *r);
+SECP256K1_INLINE static void secp256k1_fe_normalize(secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+
+    secp256k1_fe_impl_normalize(r);
+    r->magnitude = 1;
+    r->normalized = 1;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_normalize_weak(secp256k1_fe *r);
+SECP256K1_INLINE static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+
+    secp256k1_fe_impl_normalize_weak(r);
+    r->magnitude = 1;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_normalize_var(secp256k1_fe *r);
+SECP256K1_INLINE static void secp256k1_fe_normalize_var(secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+
+    secp256k1_fe_impl_normalize_var(r);
+    r->magnitude = 1;
+    r->normalized = 1;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static int secp256k1_fe_impl_normalizes_to_zero(const secp256k1_fe *r);
+SECP256K1_INLINE static int secp256k1_fe_normalizes_to_zero(const secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+
+    return secp256k1_fe_impl_normalizes_to_zero(r);
+}
+
+static int secp256k1_fe_impl_normalizes_to_zero_var(const secp256k1_fe *r);
+SECP256K1_INLINE static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+
+    return secp256k1_fe_impl_normalizes_to_zero_var(r);
+}
+
+static void secp256k1_fe_impl_set_int(secp256k1_fe *r, int a);
+SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe *r, int a) {
+    VERIFY_CHECK(0 <= a && a <= 0x7FFF);
+
+    secp256k1_fe_impl_set_int(r, a);
+    r->magnitude = (a != 0);
+    r->normalized = 1;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_add_int(secp256k1_fe *r, int a);
+SECP256K1_INLINE static void secp256k1_fe_add_int(secp256k1_fe *r, int a) {
+    VERIFY_CHECK(0 <= a && a <= 0x7FFF);
+    SECP256K1_FE_VERIFY(r);
+
+    secp256k1_fe_impl_add_int(r, a);
+    r->magnitude += 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_clear(secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe *a) {
+    a->magnitude = 0;
+    a->normalized = 1;
+    secp256k1_fe_impl_clear(a);
+
+    SECP256K1_FE_VERIFY(a);
+}
+
+static int secp256k1_fe_impl_is_zero(const secp256k1_fe *a);
+SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(a->normalized);
+
+    return secp256k1_fe_impl_is_zero(a);
+}
+
+static int secp256k1_fe_impl_is_odd(const secp256k1_fe *a);
+SECP256K1_INLINE static int secp256k1_fe_is_odd(const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(a->normalized);
+
+    return secp256k1_fe_impl_is_odd(a);
+}
+
+static int secp256k1_fe_impl_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b);
+SECP256K1_INLINE static int secp256k1_fe_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY(b);
+    VERIFY_CHECK(a->normalized);
+    VERIFY_CHECK(b->normalized);
+
+    return secp256k1_fe_impl_cmp_var(a, b);
+}
+
+static void secp256k1_fe_impl_set_b32_mod(secp256k1_fe *r, const unsigned char *a);
+SECP256K1_INLINE static void secp256k1_fe_set_b32_mod(secp256k1_fe *r, const unsigned char *a) {
+    secp256k1_fe_impl_set_b32_mod(r, a);
+    r->magnitude = 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static int secp256k1_fe_impl_set_b32_limit(secp256k1_fe *r, const unsigned char *a);
+SECP256K1_INLINE static int secp256k1_fe_set_b32_limit(secp256k1_fe *r, const unsigned char *a) {
+    if (secp256k1_fe_impl_set_b32_limit(r, a)) {
+        r->magnitude = 1;
+        r->normalized = 1;
+        SECP256K1_FE_VERIFY(r);
+        return 1;
+    } else {
+        /* Mark the output field element as invalid. */
+        r->magnitude = -1;
+        return 0;
+    }
+}
+
+static void secp256k1_fe_impl_get_b32(unsigned char *r, const secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_get_b32(unsigned char *r, const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(a->normalized);
+
+    secp256k1_fe_impl_get_b32(r, a);
+}
+
+static void secp256k1_fe_impl_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m);
+SECP256K1_INLINE static void secp256k1_fe_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m) {
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(m >= 0 && m <= 31);
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, m);
+
+    secp256k1_fe_impl_negate_unchecked(r, a, m);
+    r->magnitude = m + 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_mul_int_unchecked(secp256k1_fe *r, int a);
+SECP256K1_INLINE static void secp256k1_fe_mul_int_unchecked(secp256k1_fe *r, int a) {
+    SECP256K1_FE_VERIFY(r);
+
+    VERIFY_CHECK(a >= 0 && a <= 32);
+    VERIFY_CHECK(a*r->magnitude <= 32);
+    secp256k1_fe_impl_mul_int_unchecked(r, a);
+    r->magnitude *= a;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_add(secp256k1_fe *r, const secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_add(secp256k1_fe *r, const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(r);
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(r->magnitude + a->magnitude <= 32);
+
+    secp256k1_fe_impl_add(r, a);
+    r->magnitude += a->magnitude;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b);
+SECP256K1_INLINE static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) {
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY(b);
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, 8);
+    SECP256K1_FE_VERIFY_MAGNITUDE(b, 8);
+    VERIFY_CHECK(r != b);
+    VERIFY_CHECK(a != b);
+
+    secp256k1_fe_impl_mul(r, a, b);
+    r->magnitude = 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY_MAGNITUDE(a, 8);
+
+    secp256k1_fe_impl_sqr(r, a);
+    r->magnitude = 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag);
+SECP256K1_INLINE static void secp256k1_fe_cmov(secp256k1_fe *r, const secp256k1_fe *a, int flag) {
+    VERIFY_CHECK(flag == 0 || flag == 1);
+    SECP256K1_FE_VERIFY(a);
+    SECP256K1_FE_VERIFY(r);
+
+    secp256k1_fe_impl_cmov(r, a, flag);
+    if (a->magnitude > r->magnitude) r->magnitude = a->magnitude;
+    if (!a->normalized) r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a);
+SECP256K1_INLINE static void secp256k1_fe_to_storage(secp256k1_fe_storage *r, const secp256k1_fe *a) {
+    SECP256K1_FE_VERIFY(a);
+    VERIFY_CHECK(a->normalized);
+
+    secp256k1_fe_impl_to_storage(r, a);
+}
+
+static void secp256k1_fe_impl_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a);
+SECP256K1_INLINE static void secp256k1_fe_from_storage(secp256k1_fe *r, const secp256k1_fe_storage *a) {
+    secp256k1_fe_impl_from_storage(r, a);
+    r->magnitude = 1;
+    r->normalized = 1;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_inv(secp256k1_fe *r, const secp256k1_fe *x);
+SECP256K1_INLINE static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *x) {
+    int input_is_zero = secp256k1_fe_normalizes_to_zero(x);
+    SECP256K1_FE_VERIFY(x);
+
+    secp256k1_fe_impl_inv(r, x);
+    r->magnitude = x->magnitude > 0;
+    r->normalized = 1;
+
+    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == input_is_zero);
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_inv_var(secp256k1_fe *r, const secp256k1_fe *x);
+SECP256K1_INLINE static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *x) {
+    int input_is_zero = secp256k1_fe_normalizes_to_zero(x);
+    SECP256K1_FE_VERIFY(x);
+
+    secp256k1_fe_impl_inv_var(r, x);
+    r->magnitude = x->magnitude > 0;
+    r->normalized = 1;
+
+    VERIFY_CHECK(secp256k1_fe_normalizes_to_zero(r) == input_is_zero);
+    SECP256K1_FE_VERIFY(r);
+}
+
+static int secp256k1_fe_impl_is_square_var(const secp256k1_fe *x);
+SECP256K1_INLINE static int secp256k1_fe_is_square_var(const secp256k1_fe *x) {
+    int ret;
+    secp256k1_fe tmp = *x, sqrt;
+    SECP256K1_FE_VERIFY(x);
+
+    ret = secp256k1_fe_impl_is_square_var(x);
+    secp256k1_fe_normalize_weak(&tmp);
+    VERIFY_CHECK(ret == secp256k1_fe_sqrt(&sqrt, &tmp));
+    return ret;
+}
+
+static void secp256k1_fe_impl_get_bounds(secp256k1_fe* r, int m);
+SECP256K1_INLINE static void secp256k1_fe_get_bounds(secp256k1_fe* r, int m) {
+    VERIFY_CHECK(m >= 0);
+    VERIFY_CHECK(m <= 32);
+
+    secp256k1_fe_impl_get_bounds(r, m);
+    r->magnitude = m;
+    r->normalized = (m == 0);
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+static void secp256k1_fe_impl_half(secp256k1_fe *r);
+SECP256K1_INLINE static void secp256k1_fe_half(secp256k1_fe *r) {
+    SECP256K1_FE_VERIFY(r);
+    SECP256K1_FE_VERIFY_MAGNITUDE(r, 31);
+
+    secp256k1_fe_impl_half(r);
+    r->magnitude = (r->magnitude >> 1) + 1;
+    r->normalized = 0;
+
+    SECP256K1_FE_VERIFY(r);
+}
+
+#endif /* defined(VERIFY) */
+
 #endif /* SECP256K1_FIELD_IMPL_H */

src/group.h

@@ -44,6 +44,14 @@ typedef struct {
 
 #define SECP256K1_GE_STORAGE_CONST_GET(t) SECP256K1_FE_STORAGE_CONST_GET(t.x), SECP256K1_FE_STORAGE_CONST_GET(t.y)
 
+/** Maximum allowed magnitudes for group element coordinates
+ *  in affine (x, y) and jacobian (x, y, z) representation. */
+#define SECP256K1_GE_X_MAGNITUDE_MAX  4
+#define SECP256K1_GE_Y_MAGNITUDE_MAX  3
+#define SECP256K1_GEJ_X_MAGNITUDE_MAX 4
+#define SECP256K1_GEJ_Y_MAGNITUDE_MAX 4
+#define SECP256K1_GEJ_Z_MAGNITUDE_MAX 1
+
 /** Set a group element equal to the point with given X and Y coordinates */
 static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const secp256k1_fe *y);
 
@@ -51,6 +59,12 @@ static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const se
  *  for Y. Return value indicates whether the result is valid. */
 static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd);
 
+/** Determine whether x is a valid X coordinate on the curve. */
+static int secp256k1_ge_x_on_curve_var(const secp256k1_fe *x);
+
+/** Determine whether fraction xn/xd is a valid X coordinate on the curve (xd != 0). */
+static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe *xn, const secp256k1_fe *xd);
+
 /** Check whether a group element is the point at infinity. */
 static int secp256k1_ge_is_infinity(const secp256k1_ge *a);
 
@@ -88,6 +102,9 @@ static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a
  */
 static void secp256k1_ge_table_set_globalz(size_t len, secp256k1_ge *a, const secp256k1_fe *zr);
 
+/** Check two group elements (affine) for equality in variable time. */
+static int secp256k1_ge_eq_var(const secp256k1_ge *a, const secp256k1_ge *b);
+
 /** Set a group element (affine) equal to the point at infinity. */
 static void secp256k1_ge_set_infinity(secp256k1_ge *r);
 
@@ -100,7 +117,11 @@ static void secp256k1_gej_set_ge(secp256k1_gej *r, const secp256k1_ge *a);
 /** Check two group elements (jacobian) for equality in variable time. */
 static int secp256k1_gej_eq_var(const secp256k1_gej *a, const secp256k1_gej *b);
 
-/** Compare the X coordinate of a group element (jacobian). */
+/** Check two group elements (jacobian and affine) for equality in variable time. */
+static int secp256k1_gej_eq_ge_var(const secp256k1_gej *a, const secp256k1_ge *b);
+
+/** Compare the X coordinate of a group element (jacobian).
+  * The magnitude of the group element's X coordinate must not exceed 31. */
 static int secp256k1_gej_eq_x_var(const secp256k1_fe *x, const secp256k1_gej *a);
 
 /** Set r equal to the inverse of a (i.e., mirrored around the X axis) */
@@ -164,4 +185,12 @@ static void secp256k1_gej_rescale(secp256k1_gej *r, const secp256k1_fe *b);
  */
 static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge);
 
+/** Check invariants on an affine group element (no-op unless VERIFY is enabled). */
+static void secp256k1_ge_verify(const secp256k1_ge *a);
+#define SECP256K1_GE_VERIFY(a) secp256k1_ge_verify(a)
+
+/** Check invariants on a Jacobian group element (no-op unless VERIFY is enabled). */
+static void secp256k1_gej_verify(const secp256k1_gej *a);
+#define SECP256K1_GEJ_VERIFY(a) secp256k1_gej_verify(a)
+
 #endif /* SECP256K1_GROUP_H */

src/group_impl.h

@@ -9,90 +9,155 @@
 
 #include "field.h"
 #include "group.h"
+#include "util.h"
 
+/* Begin of section generated by sage/gen_exhaustive_groups.sage. */
+#define SECP256K1_G_ORDER_7 SECP256K1_GE_CONST(\
+    0x66625d13, 0x317ffe44, 0x63d32cff, 0x1ca02b9b,\
+    0xe5c6d070, 0x50b4b05e, 0x81cc30db, 0xf5166f0a,\
+    0x1e60e897, 0xa7c00c7c, 0x2df53eb6, 0x98274ff4,\
+    0x64252f42, 0x8ca44e17, 0x3b25418c, 0xff4ab0cf\
+)
 #define SECP256K1_G_ORDER_13 SECP256K1_GE_CONST(\
-    0xc3459c3d, 0x35326167, 0xcd86cce8, 0x07a2417f,\
-    0x5b8bd567, 0xde8538ee, 0x0d507b0c, 0xd128f5bb,\
-    0x8e467fec, 0xcd30000a, 0x6cc1184e, 0x25d382c2,\
-    0xa2f4494e, 0x2fbe9abc, 0x8b64abac, 0xd005fb24\
+    0xa2482ff8, 0x4bf34edf, 0xa51262fd, 0xe57921db,\
+    0xe0dd2cb7, 0xa5914790, 0xbc71631f, 0xc09704fb,\
+    0x942536cb, 0xa3e49492, 0x3a701cc3, 0xee3e443f,\
+    0xdf182aa9, 0x15b8aa6a, 0x166d3b19, 0xba84b045\
 )
 #define SECP256K1_G_ORDER_199 SECP256K1_GE_CONST(\
-    0x226e653f, 0xc8df7744, 0x9bacbf12, 0x7d1dcbf9,\
-    0x87f05b2a, 0xe7edbd28, 0x1f564575, 0xc48dcf18,\
-    0xa13872c2, 0xe933bb17, 0x5d9ffd5b, 0xb5b6e10c,\
-    0x57fe3c00, 0xbaaaa15a, 0xe003ec3e, 0x9c269bae\
+    0x7fb07b5c, 0xd07c3bda, 0x553902e2, 0x7a87ea2c,\
+    0x35108a7f, 0x051f41e5, 0xb76abad5, 0x1f2703ad,\
+    0x0a251539, 0x5b4c4438, 0x952a634f, 0xac10dd4d,\
+    0x6d6f4745, 0x98990c27, 0x3a4f3116, 0xd32ff969\
 )
 /** Generator for secp256k1, value 'g' defined in
  *  "Standards for Efficient Cryptography" (SEC2) 2.7.1.
  */
 #define SECP256K1_G SECP256K1_GE_CONST(\
-    0x79BE667EUL, 0xF9DCBBACUL, 0x55A06295UL, 0xCE870B07UL,\
-    0x029BFCDBUL, 0x2DCE28D9UL, 0x59F2815BUL, 0x16F81798UL,\
-    0x483ADA77UL, 0x26A3C465UL, 0x5DA4FBFCUL, 0x0E1108A8UL,\
-    0xFD17B448UL, 0xA6855419UL, 0x9C47D08FUL, 0xFB10D4B8UL\
+    0x79be667e, 0xf9dcbbac, 0x55a06295, 0xce870b07,\
+    0x029bfcdb, 0x2dce28d9, 0x59f2815b, 0x16f81798,\
+    0x483ada77, 0x26a3c465, 0x5da4fbfc, 0x0e1108a8,\
+    0xfd17b448, 0xa6855419, 0x9c47d08f, 0xfb10d4b8\
 )
 /* These exhaustive group test orders and generators are chosen such that:
  * - The field size is equal to that of secp256k1, so field code is the same.
- * - The curve equation is of the form y^2=x^3+B for some constant B.
- * - The subgroup has a generator 2*P, where P.x=1.
+ * - The curve equation is of the form y^2=x^3+B for some small constant B.
+ * - The subgroup has a generator 2*P, where P.x is as small as possible.
  * - The subgroup has size less than 1000 to permit exhaustive testing.
  * - The subgroup admits an endomorphism of the form lambda*(x,y) == (beta*x,y).
- *
- * These parameters are generated using sage/gen_exhaustive_groups.sage.
  */
 #if defined(EXHAUSTIVE_TEST_ORDER)
-#  if EXHAUSTIVE_TEST_ORDER == 13
+#  if EXHAUSTIVE_TEST_ORDER == 7
+
+static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G_ORDER_7;
+#define SECP256K1_B 6
+
+#  elif EXHAUSTIVE_TEST_ORDER == 13
+
 static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G_ORDER_13;
+#define SECP256K1_B 2
 
-static const secp256k1_fe secp256k1_fe_const_b = SECP256K1_FE_CONST(
-    0x3d3486b2, 0x159a9ca5, 0xc75638be, 0xb23a69bc,
-    0x946a45ab, 0x24801247, 0xb4ed2b8e, 0x26b6a417
-);
 #  elif EXHAUSTIVE_TEST_ORDER == 199
-static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G_ORDER_199;
 
-static const secp256k1_fe secp256k1_fe_const_b = SECP256K1_FE_CONST(
-    0x2cca28fa, 0xfc614b80, 0x2a3db42b, 0x00ba00b1,
-    0xbea8d943, 0xdace9ab2, 0x9536daea, 0x0074defb
-);
+static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G_ORDER_199;
+#define SECP256K1_B 4
+
 #  else
 #    error No known generator for the specified exhaustive test group order.
 #  endif
 #else
+
 static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G;
+#define SECP256K1_B 7
 
-static const secp256k1_fe secp256k1_fe_const_b = SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 7);
 #endif
+/* End of section generated by sage/gen_exhaustive_groups.sage. */
 
+static void secp256k1_ge_verify(const secp256k1_ge *a) {
+    SECP256K1_FE_VERIFY(&a->x);
+    SECP256K1_FE_VERIFY(&a->y);
+    SECP256K1_FE_VERIFY_MAGNITUDE(&a->x, SECP256K1_GE_X_MAGNITUDE_MAX);
+    SECP256K1_FE_VERIFY_MAGNITUDE(&a->y, SECP256K1_GE_Y_MAGNITUDE_MAX);
+    VERIFY_CHECK(a->infinity == 0 || a->infinity == 1);
+    (void)a;
+}
+
+static void secp256k1_gej_verify(const secp256k1_gej *a) {
+    SECP256K1_FE_VERIFY(&a->x);
+    SECP256K1_FE_VERIFY(&a->y);
+    SECP256K1_FE_VERIFY(&a->z);
+    SECP256K1_FE_VERIFY_MAGNITUDE(&a->x, SECP256K1_GEJ_X_MAGNITUDE_MAX);
+    SECP256K1_FE_VERIFY_MAGNITUDE(&a->y, SECP256K1_GEJ_Y_MAGNITUDE_MAX);
+    SECP256K1_FE_VERIFY_MAGNITUDE(&a->z, SECP256K1_GEJ_Z_MAGNITUDE_MAX);
+    VERIFY_CHECK(a->infinity == 0 || a->infinity == 1);
+    (void)a;
+}
+
+/* Set r to the affine coordinates of Jacobian point (a.x, a.y, 1/zi). */
 static void secp256k1_ge_set_gej_zinv(secp256k1_ge *r, const secp256k1_gej *a, const secp256k1_fe *zi) {
     secp256k1_fe zi2;
     secp256k1_fe zi3;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_FE_VERIFY(zi);
     VERIFY_CHECK(!a->infinity);
+
     secp256k1_fe_sqr(&zi2, zi);
     secp256k1_fe_mul(&zi3, &zi2, zi);
     secp256k1_fe_mul(&r->x, &a->x, &zi2);
     secp256k1_fe_mul(&r->y, &a->y, &zi3);
     r->infinity = a->infinity;
+
+    SECP256K1_GE_VERIFY(r);
+}
+
+/* Set r to the affine coordinates of Jacobian point (a.x, a.y, 1/zi). */
+static void secp256k1_ge_set_ge_zinv(secp256k1_ge *r, const secp256k1_ge *a, const secp256k1_fe *zi) {
+    secp256k1_fe zi2;
+    secp256k1_fe zi3;
+    SECP256K1_GE_VERIFY(a);
+    SECP256K1_FE_VERIFY(zi);
+    VERIFY_CHECK(!a->infinity);
+
+    secp256k1_fe_sqr(&zi2, zi);
+    secp256k1_fe_mul(&zi3, &zi2, zi);
+    secp256k1_fe_mul(&r->x, &a->x, &zi2);
+    secp256k1_fe_mul(&r->y, &a->y, &zi3);
+    r->infinity = a->infinity;
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const secp256k1_fe *y) {
+    SECP256K1_FE_VERIFY(x);
+    SECP256K1_FE_VERIFY(y);
+
     r->infinity = 0;
     r->x = *x;
     r->y = *y;
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static int secp256k1_ge_is_infinity(const secp256k1_ge *a) {
+    SECP256K1_GE_VERIFY(a);
+
     return a->infinity;
 }
 
 static void secp256k1_ge_neg(secp256k1_ge *r, const secp256k1_ge *a) {
+    SECP256K1_GE_VERIFY(a);
+
     *r = *a;
     secp256k1_fe_normalize_weak(&r->y);
     secp256k1_fe_negate(&r->y, &r->y, 1);
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static void secp256k1_ge_set_gej(secp256k1_ge *r, secp256k1_gej *a) {
     secp256k1_fe z2, z3;
+    SECP256K1_GEJ_VERIFY(a);
+
     r->infinity = a->infinity;
     secp256k1_fe_inv(&a->z, &a->z);
     secp256k1_fe_sqr(&z2, &a->z);
@@ -102,14 +167,20 @@ static void secp256k1_ge_set_gej(secp256k1_ge *r, secp256k1_gej *a) {
     secp256k1_fe_set_int(&a->z, 1);
     r->x = a->x;
     r->y = a->y;
+
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(r);
 }
 
 static void secp256k1_ge_set_gej_var(secp256k1_ge *r, secp256k1_gej *a) {
     secp256k1_fe z2, z3;
-    if (a->infinity) {
+    SECP256K1_GEJ_VERIFY(a);
+
+    if (secp256k1_gej_is_infinity(a)) {
         secp256k1_ge_set_infinity(r);
         return;
     }
+    r->infinity = 0;
     secp256k1_fe_inv_var(&a->z, &a->z);
     secp256k1_fe_sqr(&z2, &a->z);
     secp256k1_fe_mul(&z3, &a->z, &z2);
@@ -117,12 +188,20 @@ static void secp256k1_ge_set_gej_var(secp256k1_ge *r, secp256k1_gej *a) {
     secp256k1_fe_mul(&a->y, &a->y, &z3);
     secp256k1_fe_set_int(&a->z, 1);
     secp256k1_ge_set_xy(r, &a->x, &a->y);
+
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(r);
 }
 
 static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a, size_t len) {
     secp256k1_fe u;
     size_t i;
     size_t last_i = SIZE_MAX;
+#ifdef VERIFY
+    for (i = 0; i < len; i++) {
+        SECP256K1_GEJ_VERIFY(&a[i]);
+    }
+#endif
 
     for (i = 0; i < len; i++) {
         if (a[i].infinity) {
@@ -159,30 +238,45 @@ static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a
             secp256k1_ge_set_gej_zinv(&r[i], &a[i], &r[i].x);
         }
     }
+
+#ifdef VERIFY
+    for (i = 0; i < len; i++) {
+        SECP256K1_GE_VERIFY(&r[i]);
+    }
+#endif
 }
 
 static void secp256k1_ge_table_set_globalz(size_t len, secp256k1_ge *a, const secp256k1_fe *zr) {
-    size_t i = len - 1;
+    size_t i;
     secp256k1_fe zs;
+#ifdef VERIFY
+    for (i = 0; i < len; i++) {
+        SECP256K1_GE_VERIFY(&a[i]);
+        SECP256K1_FE_VERIFY(&zr[i]);
+    }
+#endif
 
     if (len > 0) {
+        i = len - 1;
         /* Ensure all y values are in weak normal form for fast negation of points */
         secp256k1_fe_normalize_weak(&a[i].y);
         zs = zr[i];
 
         /* Work our way backwards, using the z-ratios to scale the x/y values. */
         while (i > 0) {
-            secp256k1_gej tmpa;
             if (i != len - 1) {
                 secp256k1_fe_mul(&zs, &zs, &zr[i]);
             }
             i--;
-            tmpa.x = a[i].x;
-            tmpa.y = a[i].y;
-            tmpa.infinity = 0;
-            secp256k1_ge_set_gej_zinv(&a[i], &tmpa, &zs);
+            secp256k1_ge_set_ge_zinv(&a[i], &a[i], &zs);
         }
     }
+
+#ifdef VERIFY
+    for (i = 0; i < len; i++) {
+        SECP256K1_GE_VERIFY(&a[i]);
+    }
+#endif
 }
 
 static void secp256k1_gej_set_infinity(secp256k1_gej *r) {
@@ -190,12 +284,16 @@ static void secp256k1_gej_set_infinity(secp256k1_gej *r) {
     secp256k1_fe_clear(&r->x);
     secp256k1_fe_clear(&r->y);
     secp256k1_fe_clear(&r->z);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_ge_set_infinity(secp256k1_ge *r) {
     r->infinity = 1;
     secp256k1_fe_clear(&r->x);
     secp256k1_fe_clear(&r->y);
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static void secp256k1_gej_clear(secp256k1_gej *r) {
@@ -203,83 +301,135 @@ static void secp256k1_gej_clear(secp256k1_gej *r) {
     secp256k1_fe_clear(&r->x);
     secp256k1_fe_clear(&r->y);
     secp256k1_fe_clear(&r->z);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_ge_clear(secp256k1_ge *r) {
     r->infinity = 0;
     secp256k1_fe_clear(&r->x);
     secp256k1_fe_clear(&r->y);
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd) {
     secp256k1_fe x2, x3;
+    int ret;
+    SECP256K1_FE_VERIFY(x);
+
     r->x = *x;
     secp256k1_fe_sqr(&x2, x);
     secp256k1_fe_mul(&x3, x, &x2);
     r->infinity = 0;
-    secp256k1_fe_add(&x3, &secp256k1_fe_const_b);
-    if (!secp256k1_fe_sqrt(&r->y, &x3)) {
-        return 0;
-    }
+    secp256k1_fe_add_int(&x3, SECP256K1_B);
+    ret = secp256k1_fe_sqrt(&r->y, &x3);
     secp256k1_fe_normalize_var(&r->y);
     if (secp256k1_fe_is_odd(&r->y) != odd) {
         secp256k1_fe_negate(&r->y, &r->y, 1);
     }
-    return 1;
 
+    SECP256K1_GE_VERIFY(r);
+    return ret;
 }
 
 static void secp256k1_gej_set_ge(secp256k1_gej *r, const secp256k1_ge *a) {
+   SECP256K1_GE_VERIFY(a);
+
    r->infinity = a->infinity;
    r->x = a->x;
    r->y = a->y;
    secp256k1_fe_set_int(&r->z, 1);
+
+   SECP256K1_GEJ_VERIFY(r);
 }
 
 static int secp256k1_gej_eq_var(const secp256k1_gej *a, const secp256k1_gej *b) {
     secp256k1_gej tmp;
+    SECP256K1_GEJ_VERIFY(b);
+    SECP256K1_GEJ_VERIFY(a);
+
     secp256k1_gej_neg(&tmp, a);
     secp256k1_gej_add_var(&tmp, &tmp, b, NULL);
     return secp256k1_gej_is_infinity(&tmp);
 }
 
+static int secp256k1_gej_eq_ge_var(const secp256k1_gej *a, const secp256k1_ge *b) {
+    secp256k1_gej tmp;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(b);
+
+    secp256k1_gej_neg(&tmp, a);
+    secp256k1_gej_add_ge_var(&tmp, &tmp, b, NULL);
+    return secp256k1_gej_is_infinity(&tmp);
+}
+
+static int secp256k1_ge_eq_var(const secp256k1_ge *a, const secp256k1_ge *b) {
+    secp256k1_fe tmp;
+    SECP256K1_GE_VERIFY(a);
+    SECP256K1_GE_VERIFY(b);
+
+    if (a->infinity != b->infinity) return 0;
+    if (a->infinity) return 1;
+
+    tmp = a->x;
+    secp256k1_fe_normalize_weak(&tmp);
+    if (!secp256k1_fe_equal(&tmp, &b->x)) return 0;
+
+    tmp = a->y;
+    secp256k1_fe_normalize_weak(&tmp);
+    if (!secp256k1_fe_equal(&tmp, &b->y)) return 0;
+
+    return 1;
+}
+
 static int secp256k1_gej_eq_x_var(const secp256k1_fe *x, const secp256k1_gej *a) {
-    secp256k1_fe r, r2;
+    secp256k1_fe r;
+    SECP256K1_FE_VERIFY(x);
+    SECP256K1_GEJ_VERIFY(a);
     VERIFY_CHECK(!a->infinity);
+
     secp256k1_fe_sqr(&r, &a->z); secp256k1_fe_mul(&r, &r, x);
-    r2 = a->x; secp256k1_fe_normalize_weak(&r2);
-    return secp256k1_fe_equal_var(&r, &r2);
+    return secp256k1_fe_equal(&r, &a->x);
 }
 
 static void secp256k1_gej_neg(secp256k1_gej *r, const secp256k1_gej *a) {
+    SECP256K1_GEJ_VERIFY(a);
+
     r->infinity = a->infinity;
     r->x = a->x;
     r->y = a->y;
     r->z = a->z;
     secp256k1_fe_normalize_weak(&r->y);
     secp256k1_fe_negate(&r->y, &r->y, 1);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static int secp256k1_gej_is_infinity(const secp256k1_gej *a) {
+    SECP256K1_GEJ_VERIFY(a);
+
     return a->infinity;
 }
 
 static int secp256k1_ge_is_valid_var(const secp256k1_ge *a) {
     secp256k1_fe y2, x3;
+    SECP256K1_GE_VERIFY(a);
+
     if (a->infinity) {
         return 0;
     }
     /* y^2 = x^3 + 7 */
     secp256k1_fe_sqr(&y2, &a->y);
     secp256k1_fe_sqr(&x3, &a->x); secp256k1_fe_mul(&x3, &x3, &a->x);
-    secp256k1_fe_add(&x3, &secp256k1_fe_const_b);
-    secp256k1_fe_normalize_weak(&x3);
-    return secp256k1_fe_equal_var(&y2, &x3);
+    secp256k1_fe_add_int(&x3, SECP256K1_B);
+    return secp256k1_fe_equal(&y2, &x3);
 }
 
 static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a) {
     /* Operations: 3 mul, 4 sqr, 8 add/half/mul_int/negate */
     secp256k1_fe l, s, t;
+    SECP256K1_GEJ_VERIFY(a);
 
     r->infinity = a->infinity;
 
@@ -307,9 +457,13 @@ static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp25
     secp256k1_fe_mul(&r->y, &t, &l);       /* Y3 = L*(X3 + T) (1) */
     secp256k1_fe_add(&r->y, &s);           /* Y3 = L*(X3 + T) + S^2 (2) */
     secp256k1_fe_negate(&r->y, &r->y, 2);  /* Y3 = -(L*(X3 + T) + S^2) (3) */
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe *rzr) {
+    SECP256K1_GEJ_VERIFY(a);
+
     /** For secp256k1, 2Q is infinity if and only if Q is infinity. This is because if 2Q = infinity,
      *  Q must equal -Q, or that Q.y == -(Q.y), or Q.y is 0. For a point on y^2 = x^3 + 7 to have
      *  y=0, x^3 must be -7 mod p. However, -7 has no cube root mod p.
@@ -334,11 +488,15 @@ static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, s
     }
 
     secp256k1_gej_double(r, a);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_gej *b, secp256k1_fe *rzr) {
     /* 12 mul, 4 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */
     secp256k1_fe z22, z12, u1, u2, s1, s2, h, i, h2, h3, t;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GEJ_VERIFY(b);
 
     if (a->infinity) {
         VERIFY_CHECK(rzr == NULL);
@@ -394,11 +552,16 @@ static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, cons
     secp256k1_fe_mul(&r->y, &t, &i);
     secp256k1_fe_mul(&h3, &h3, &s1);
     secp256k1_fe_add(&r->y, &h3);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b, secp256k1_fe *rzr) {
-    /* 8 mul, 3 sqr, 13 add/negate/normalize_weak/normalizes_to_zero (ignoring special cases) */
+    /* Operations: 8 mul, 3 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */
     secp256k1_fe z12, u1, u2, s1, s2, h, i, h2, h3, t;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(b);
+
     if (a->infinity) {
         VERIFY_CHECK(rzr == NULL);
         secp256k1_gej_set_ge(r, b);
@@ -413,11 +576,11 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c
     }
 
     secp256k1_fe_sqr(&z12, &a->z);
-    u1 = a->x; secp256k1_fe_normalize_weak(&u1);
+    u1 = a->x;
     secp256k1_fe_mul(&u2, &b->x, &z12);
-    s1 = a->y; secp256k1_fe_normalize_weak(&s1);
+    s1 = a->y;
     secp256k1_fe_mul(&s2, &b->y, &z12); secp256k1_fe_mul(&s2, &s2, &a->z);
-    secp256k1_fe_negate(&h, &u1, 1); secp256k1_fe_add(&h, &u2);
+    secp256k1_fe_negate(&h, &u1, SECP256K1_GEJ_X_MAGNITUDE_MAX); secp256k1_fe_add(&h, &u2);
     secp256k1_fe_negate(&i, &s2, 1); secp256k1_fe_add(&i, &s1);
     if (secp256k1_fe_normalizes_to_zero_var(&h)) {
         if (secp256k1_fe_normalizes_to_zero_var(&i)) {
@@ -451,11 +614,17 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c
     secp256k1_fe_mul(&r->y, &t, &i);
     secp256k1_fe_mul(&h3, &h3, &s1);
     secp256k1_fe_add(&r->y, &h3);
+
+    SECP256K1_GEJ_VERIFY(r);
+    if (rzr != NULL) SECP256K1_FE_VERIFY(rzr);
 }
 
 static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b, const secp256k1_fe *bzinv) {
-    /* 9 mul, 3 sqr, 13 add/negate/normalize_weak/normalizes_to_zero (ignoring special cases) */
+    /* Operations: 9 mul, 3 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */
     secp256k1_fe az, z12, u1, u2, s1, s2, h, i, h2, h3, t;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(b);
+    SECP256K1_FE_VERIFY(bzinv);
 
     if (a->infinity) {
         secp256k1_fe bzinv2, bzinv3;
@@ -465,6 +634,7 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a,
         secp256k1_fe_mul(&r->x, &b->x, &bzinv2);
         secp256k1_fe_mul(&r->y, &b->y, &bzinv3);
         secp256k1_fe_set_int(&r->z, 1);
+        SECP256K1_GEJ_VERIFY(r);
         return;
     }
     if (b->infinity) {
@@ -483,11 +653,11 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a,
     secp256k1_fe_mul(&az, &a->z, bzinv);
 
     secp256k1_fe_sqr(&z12, &az);
-    u1 = a->x; secp256k1_fe_normalize_weak(&u1);
+    u1 = a->x;
     secp256k1_fe_mul(&u2, &b->x, &z12);
-    s1 = a->y; secp256k1_fe_normalize_weak(&s1);
+    s1 = a->y;
     secp256k1_fe_mul(&s2, &b->y, &z12); secp256k1_fe_mul(&s2, &s2, &az);
-    secp256k1_fe_negate(&h, &u1, 1); secp256k1_fe_add(&h, &u2);
+    secp256k1_fe_negate(&h, &u1, SECP256K1_GEJ_X_MAGNITUDE_MAX); secp256k1_fe_add(&h, &u2);
     secp256k1_fe_negate(&i, &s2, 1); secp256k1_fe_add(&i, &s1);
     if (secp256k1_fe_normalizes_to_zero_var(&h)) {
         if (secp256k1_fe_normalizes_to_zero_var(&i)) {
@@ -515,18 +685,21 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a,
     secp256k1_fe_mul(&r->y, &t, &i);
     secp256k1_fe_mul(&h3, &h3, &s1);
     secp256k1_fe_add(&r->y, &h3);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 
 static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b) {
-    /* Operations: 7 mul, 5 sqr, 24 add/cmov/half/mul_int/negate/normalize_weak/normalizes_to_zero */
+    /* Operations: 7 mul, 5 sqr, 21 add/cmov/half/mul_int/negate/normalizes_to_zero */
     secp256k1_fe zz, u1, u2, s1, s2, t, tt, m, n, q, rr;
     secp256k1_fe m_alt, rr_alt;
-    int infinity, degenerate;
+    int degenerate;
+    SECP256K1_GEJ_VERIFY(a);
+    SECP256K1_GE_VERIFY(b);
     VERIFY_CHECK(!b->infinity);
-    VERIFY_CHECK(a->infinity == 0 || a->infinity == 1);
 
-    /** In:
+    /*  In:
      *    Eric Brier and Marc Joye, Weierstrass Elliptic Curves and Side-Channel Attacks.
      *    In D. Naccache and P. Paillier, Eds., Public Key Cryptography, vol. 2274 of Lecture Notes in Computer Science, pages 335-345. Springer-Verlag, 2002.
      *  we find as solution for a unified addition/doubling formula:
@@ -577,78 +750,104 @@ static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const
      */
 
     secp256k1_fe_sqr(&zz, &a->z);                       /* z = Z1^2 */
-    u1 = a->x; secp256k1_fe_normalize_weak(&u1);        /* u1 = U1 = X1*Z2^2 (1) */
+    u1 = a->x;                                          /* u1 = U1 = X1*Z2^2 (GEJ_X_M) */
     secp256k1_fe_mul(&u2, &b->x, &zz);                  /* u2 = U2 = X2*Z1^2 (1) */
-    s1 = a->y; secp256k1_fe_normalize_weak(&s1);        /* s1 = S1 = Y1*Z2^3 (1) */
+    s1 = a->y;                                          /* s1 = S1 = Y1*Z2^3 (GEJ_Y_M) */
     secp256k1_fe_mul(&s2, &b->y, &zz);                  /* s2 = Y2*Z1^2 (1) */
     secp256k1_fe_mul(&s2, &s2, &a->z);                  /* s2 = S2 = Y2*Z1^3 (1) */
-    t = u1; secp256k1_fe_add(&t, &u2);                  /* t = T = U1+U2 (2) */
-    m = s1; secp256k1_fe_add(&m, &s2);                  /* m = M = S1+S2 (2) */
+    t = u1; secp256k1_fe_add(&t, &u2);                  /* t = T = U1+U2 (GEJ_X_M+1) */
+    m = s1; secp256k1_fe_add(&m, &s2);                  /* m = M = S1+S2 (GEJ_Y_M+1) */
     secp256k1_fe_sqr(&rr, &t);                          /* rr = T^2 (1) */
-    secp256k1_fe_negate(&m_alt, &u2, 1);                /* Malt = -X2*Z1^2 */
-    secp256k1_fe_mul(&tt, &u1, &m_alt);                 /* tt = -U1*U2 (2) */
-    secp256k1_fe_add(&rr, &tt);                         /* rr = R = T^2-U1*U2 (3) */
-    /** If lambda = R/M = 0/0 we have a problem (except in the "trivial"
-     *  case that Z = z1z2 = 0, and this is special-cased later on). */
-    degenerate = secp256k1_fe_normalizes_to_zero(&m) &
-                 secp256k1_fe_normalizes_to_zero(&rr);
+    secp256k1_fe_negate(&m_alt, &u2, 1);                /* Malt = -X2*Z1^2 (2) */
+    secp256k1_fe_mul(&tt, &u1, &m_alt);                 /* tt = -U1*U2 (1) */
+    secp256k1_fe_add(&rr, &tt);                         /* rr = R = T^2-U1*U2 (2) */
+    /* If lambda = R/M = R/0 we have a problem (except in the "trivial"
+     * case that Z = z1z2 = 0, and this is special-cased later on). */
+    degenerate = secp256k1_fe_normalizes_to_zero(&m);
     /* This only occurs when y1 == -y2 and x1^3 == x2^3, but x1 != x2.
      * This means either x1 == beta*x2 or beta*x1 == x2, where beta is
      * a nontrivial cube root of one. In either case, an alternate
      * non-indeterminate expression for lambda is (y1 - y2)/(x1 - x2),
      * so we set R/M equal to this. */
     rr_alt = s1;
-    secp256k1_fe_mul_int(&rr_alt, 2);       /* rr = Y1*Z2^3 - Y2*Z1^3 (2) */
-    secp256k1_fe_add(&m_alt, &u1);          /* Malt = X1*Z2^2 - X2*Z1^2 */
+    secp256k1_fe_mul_int(&rr_alt, 2);       /* rr_alt = Y1*Z2^3 - Y2*Z1^3 (GEJ_Y_M*2) */
+    secp256k1_fe_add(&m_alt, &u1);          /* Malt = X1*Z2^2 - X2*Z1^2 (GEJ_X_M+2) */
 
-    secp256k1_fe_cmov(&rr_alt, &rr, !degenerate);
-    secp256k1_fe_cmov(&m_alt, &m, !degenerate);
-    /* Now Ralt / Malt = lambda and is guaranteed not to be 0/0.
+    secp256k1_fe_cmov(&rr_alt, &rr, !degenerate);       /* rr_alt (GEJ_Y_M*2) */
+    secp256k1_fe_cmov(&m_alt, &m, !degenerate);         /* m_alt (GEJ_X_M+2) */
+    /* Now Ralt / Malt = lambda and is guaranteed not to be Ralt / 0.
      * From here on out Ralt and Malt represent the numerator
      * and denominator of lambda; R and M represent the explicit
      * expressions x1^2 + x2^2 + x1x2 and y1 + y2. */
     secp256k1_fe_sqr(&n, &m_alt);                       /* n = Malt^2 (1) */
-    secp256k1_fe_negate(&q, &t, 2);                     /* q = -T (3) */
+    secp256k1_fe_negate(&q, &t,
+        SECP256K1_GEJ_X_MAGNITUDE_MAX + 1);             /* q = -T (GEJ_X_M+2) */
     secp256k1_fe_mul(&q, &q, &n);                       /* q = Q = -T*Malt^2 (1) */
     /* These two lines use the observation that either M == Malt or M == 0,
      * so M^3 * Malt is either Malt^4 (which is computed by squaring), or
      * zero (which is "computed" by cmov). So the cost is one squaring
      * versus two multiplications. */
-    secp256k1_fe_sqr(&n, &n);
-    secp256k1_fe_cmov(&n, &m, degenerate);              /* n = M^3 * Malt (2) */
+    secp256k1_fe_sqr(&n, &n);                           /* n = Malt^4 (1) */
+    secp256k1_fe_cmov(&n, &m, degenerate);              /* n = M^3 * Malt (GEJ_Y_M+1) */
     secp256k1_fe_sqr(&t, &rr_alt);                      /* t = Ralt^2 (1) */
     secp256k1_fe_mul(&r->z, &a->z, &m_alt);             /* r->z = Z3 = Malt*Z (1) */
-    infinity = secp256k1_fe_normalizes_to_zero(&r->z) & ~a->infinity;
     secp256k1_fe_add(&t, &q);                           /* t = Ralt^2 + Q (2) */
     r->x = t;                                           /* r->x = X3 = Ralt^2 + Q (2) */
     secp256k1_fe_mul_int(&t, 2);                        /* t = 2*X3 (4) */
     secp256k1_fe_add(&t, &q);                           /* t = 2*X3 + Q (5) */
     secp256k1_fe_mul(&t, &t, &rr_alt);                  /* t = Ralt*(2*X3 + Q) (1) */
-    secp256k1_fe_add(&t, &n);                           /* t = Ralt*(2*X3 + Q) + M^3*Malt (3) */
-    secp256k1_fe_negate(&r->y, &t, 3);                  /* r->y = -(Ralt*(2*X3 + Q) + M^3*Malt) (4) */
-    secp256k1_fe_half(&r->y);                           /* r->y = Y3 = -(Ralt*(2*X3 + Q) + M^3*Malt)/2 (3) */
+    secp256k1_fe_add(&t, &n);                           /* t = Ralt*(2*X3 + Q) + M^3*Malt (GEJ_Y_M+2) */
+    secp256k1_fe_negate(&r->y, &t,
+        SECP256K1_GEJ_Y_MAGNITUDE_MAX + 2);             /* r->y = -(Ralt*(2*X3 + Q) + M^3*Malt) (GEJ_Y_M+3) */
+    secp256k1_fe_half(&r->y);                           /* r->y = Y3 = -(Ralt*(2*X3 + Q) + M^3*Malt)/2 ((GEJ_Y_M+3)/2 + 1) */
 
-    /** In case a->infinity == 1, replace r with (b->x, b->y, 1). */
+    /* In case a->infinity == 1, replace r with (b->x, b->y, 1). */
     secp256k1_fe_cmov(&r->x, &b->x, a->infinity);
     secp256k1_fe_cmov(&r->y, &b->y, a->infinity);
     secp256k1_fe_cmov(&r->z, &secp256k1_fe_one, a->infinity);
-    r->infinity = infinity;
+
+    /* Set r->infinity if r->z is 0.
+     *
+     * If a->infinity is set, then r->infinity = (r->z == 0) = (1 == 0) = false,
+     * which is correct because the function assumes that b is not infinity.
+     *
+     * Now assume !a->infinity. This implies Z = Z1 != 0.
+     *
+     * Case y1 = -y2:
+     * In this case we could have a = -b, namely if x1 = x2.
+     * We have degenerate = true, r->z = (x1 - x2) * Z.
+     * Then r->infinity = ((x1 - x2)Z == 0) = (x1 == x2) = (a == -b).
+     *
+     * Case y1 != -y2:
+     * In this case, we can't have a = -b.
+     * We have degenerate = false, r->z = (y1 + y2) * Z.
+     * Then r->infinity = ((y1 + y2)Z == 0) = (y1 == -y2) = false. */
+    r->infinity = secp256k1_fe_normalizes_to_zero(&r->z);
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_gej_rescale(secp256k1_gej *r, const secp256k1_fe *s) {
     /* Operations: 4 mul, 1 sqr */
     secp256k1_fe zz;
-    VERIFY_CHECK(!secp256k1_fe_is_zero(s));
+    SECP256K1_GEJ_VERIFY(r);
+    SECP256K1_FE_VERIFY(s);
+    VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(s));
+
     secp256k1_fe_sqr(&zz, s);
     secp256k1_fe_mul(&r->x, &r->x, &zz);                /* r->x *= s^2 */
     secp256k1_fe_mul(&r->y, &r->y, &zz);
     secp256k1_fe_mul(&r->y, &r->y, s);                  /* r->y *= s^3 */
     secp256k1_fe_mul(&r->z, &r->z, s);                  /* r->z *= s   */
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static void secp256k1_ge_to_storage(secp256k1_ge_storage *r, const secp256k1_ge *a) {
     secp256k1_fe x, y;
+    SECP256K1_GE_VERIFY(a);
     VERIFY_CHECK(!a->infinity);
+
     x = a->x;
     secp256k1_fe_normalize(&x);
     y = a->y;
@@ -661,14 +860,20 @@ static void secp256k1_ge_from_storage(secp256k1_ge *r, const secp256k1_ge_storag
     secp256k1_fe_from_storage(&r->x, &a->x);
     secp256k1_fe_from_storage(&r->y, &a->y);
     r->infinity = 0;
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static SECP256K1_INLINE void secp256k1_gej_cmov(secp256k1_gej *r, const secp256k1_gej *a, int flag) {
+    SECP256K1_GEJ_VERIFY(r);
+    SECP256K1_GEJ_VERIFY(a);
+
     secp256k1_fe_cmov(&r->x, &a->x, flag);
     secp256k1_fe_cmov(&r->y, &a->y, flag);
     secp256k1_fe_cmov(&r->z, &a->z, flag);
-
     r->infinity ^= (r->infinity ^ a->infinity) & flag;
+
+    SECP256K1_GEJ_VERIFY(r);
 }
 
 static SECP256K1_INLINE void secp256k1_ge_storage_cmov(secp256k1_ge_storage *r, const secp256k1_ge_storage *a, int flag) {
@@ -677,14 +882,19 @@ static SECP256K1_INLINE void secp256k1_ge_storage_cmov(secp256k1_ge_storage *r,
 }
 
 static void secp256k1_ge_mul_lambda(secp256k1_ge *r, const secp256k1_ge *a) {
+    SECP256K1_GE_VERIFY(a);
+
     *r = *a;
     secp256k1_fe_mul(&r->x, &r->x, &secp256k1_const_beta);
+
+    SECP256K1_GE_VERIFY(r);
 }
 
 static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) {
 #ifdef EXHAUSTIVE_TEST_ORDER
     secp256k1_gej out;
     int i;
+    SECP256K1_GE_VERIFY(ge);
 
     /* A very simple EC multiplication ladder that avoids a dependency on ecmult. */
     secp256k1_gej_set_infinity(&out);
@@ -696,10 +906,39 @@ static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) {
     }
     return secp256k1_gej_is_infinity(&out);
 #else
+    SECP256K1_GE_VERIFY(ge);
+
     (void)ge;
     /* The real secp256k1 group has cofactor 1, so the subgroup is the entire curve. */
     return 1;
 #endif
 }
 
+static int secp256k1_ge_x_on_curve_var(const secp256k1_fe *x) {
+    secp256k1_fe c;
+    secp256k1_fe_sqr(&c, x);
+    secp256k1_fe_mul(&c, &c, x);
+    secp256k1_fe_add_int(&c, SECP256K1_B);
+    return secp256k1_fe_is_square_var(&c);
+}
+
+static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe *xn, const secp256k1_fe *xd) {
+    /* We want to determine whether (xn/xd) is on the curve.
+     *
+     * (xn/xd)^3 + 7 is square <=> xd*xn^3 + 7*xd^4 is square (multiplying by xd^4, a square).
+     */
+     secp256k1_fe r, t;
+     VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(xd));
+
+     secp256k1_fe_mul(&r, xd, xn); /* r = xd*xn */
+     secp256k1_fe_sqr(&t, xn); /* t = xn^2 */
+     secp256k1_fe_mul(&r, &r, &t); /* r = xd*xn^3 */
+     secp256k1_fe_sqr(&t, xd); /* t = xd^2 */
+     secp256k1_fe_sqr(&t, &t); /* t = xd^4 */
+     VERIFY_CHECK(SECP256K1_B <= 31);
+     secp256k1_fe_mul_int(&t, SECP256K1_B); /* t = 7*xd^4 */
+     secp256k1_fe_add(&r, &t); /* r = xd*xn^3 + 7*xd^4 */
+     return secp256k1_fe_is_square_var(&r);
+}
+
 #endif /* SECP256K1_GROUP_IMPL_H */

src/hash_impl.h

@@ -138,7 +138,7 @@ static void secp256k1_sha256_write(secp256k1_sha256 *hash, const unsigned char *
     }
     if (len) {
         /* Fill the buffer with what remains. */
-        memcpy(((unsigned char*)hash->buf) + bufsize, data, len);
+        memcpy(hash->buf + bufsize, data, len);
     }
 }
 

src/int128.h

@@ -66,7 +66,12 @@ static SECP256K1_INLINE void secp256k1_i128_det(secp256k1_int128 *r, int64_t a,
  */
 static SECP256K1_INLINE void secp256k1_i128_rshift(secp256k1_int128 *r, unsigned int b);
 
-/* Return the low 64-bits of a 128-bit value interpreted as an signed 64-bit value. */
+/* Return the input value modulo 2^64. */
+static SECP256K1_INLINE uint64_t secp256k1_i128_to_u64(const secp256k1_int128 *a);
+
+/* Return the value as a signed 64-bit value.
+ * Requires the input to be between INT64_MIN and INT64_MAX.
+ */
 static SECP256K1_INLINE int64_t secp256k1_i128_to_i64(const secp256k1_int128 *a);
 
 /* Write a signed 64-bit value to r. */
@@ -75,10 +80,10 @@ static SECP256K1_INLINE void secp256k1_i128_from_i64(secp256k1_int128 *r, int64_
 /* Compare two 128-bit values for equality. */
 static SECP256K1_INLINE int secp256k1_i128_eq_var(const secp256k1_int128 *a, const secp256k1_int128 *b);
 
-/* Tests if r is equal to 2^n.
+/* Tests if r is equal to sign*2^n (sign must be 1 or -1).
  * n must be strictly less than 127.
  */
-static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n);
+static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n, int sign);
 
 #endif
 

src/int128_native_impl.h

@@ -2,6 +2,7 @@
 #define SECP256K1_INT128_NATIVE_IMPL_H
 
 #include "int128.h"
+#include "util.h"
 
 static SECP256K1_INLINE void secp256k1_u128_load(secp256k1_uint128 *r, uint64_t hi, uint64_t lo) {
     *r = (((uint128_t)hi) << 64) + lo;
@@ -67,7 +68,12 @@ static SECP256K1_INLINE void secp256k1_i128_rshift(secp256k1_int128 *r, unsigned
    *r >>= n;
 }
 
+static SECP256K1_INLINE uint64_t secp256k1_i128_to_u64(const secp256k1_int128 *a) {
+   return (uint64_t)*a;
+}
+
 static SECP256K1_INLINE int64_t secp256k1_i128_to_i64(const secp256k1_int128 *a) {
+   VERIFY_CHECK(INT64_MIN <= *a && *a <= INT64_MAX);
    return *a;
 }
 
@@ -79,9 +85,10 @@ static SECP256K1_INLINE int secp256k1_i128_eq_var(const secp256k1_int128 *a, con
    return *a == *b;
 }
 
-static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n) {
+static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n, int sign) {
    VERIFY_CHECK(n < 127);
-   return (*r == (int128_t)1 << n);
+   VERIFY_CHECK(sign == 1 || sign == -1);
+   return (*r == (int128_t)((uint128_t)sign << n));
 }
 
 #endif

src/int128_struct_impl.h

@@ -2,6 +2,7 @@
 #define SECP256K1_INT128_STRUCT_IMPL_H
 
 #include "int128.h"
+#include "util.h"
 
 #if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) /* MSVC */
 #    include <intrin.h>
@@ -79,7 +80,12 @@ static SECP256K1_INLINE void secp256k1_u128_rshift(secp256k1_uint128 *r, unsigne
      r->lo = r->hi >> (n-64);
      r->hi = 0;
    } else if (n > 0) {
+#if defined(_MSC_VER) && defined(_M_X64)
+     VERIFY_CHECK(n < 64);
+     r->lo = __shiftright128(r->lo, r->hi, n);
+#else
      r->lo = ((1U * r->hi) << (64-n)) | r->lo >> n;
+#endif
      r->hi >>= n;
    }
 }
@@ -170,8 +176,14 @@ static SECP256K1_INLINE void secp256k1_i128_rshift(secp256k1_int128 *r, unsigned
    }
 }
 
+static SECP256K1_INLINE uint64_t secp256k1_i128_to_u64(const secp256k1_int128 *a) {
+   return a->lo;
+}
+
 static SECP256K1_INLINE int64_t secp256k1_i128_to_i64(const secp256k1_int128 *a) {
-   return (int64_t)a->lo;
+   /* Verify that a represents a 64 bit signed value by checking that the high bits are a sign extension of the low bits. */
+   VERIFY_CHECK(a->hi == -(a->lo >> 63));
+   return (int64_t)secp256k1_i128_to_u64(a);
 }
 
 static SECP256K1_INLINE void secp256k1_i128_from_i64(secp256k1_int128 *r, int64_t a) {
@@ -183,10 +195,11 @@ static SECP256K1_INLINE int secp256k1_i128_eq_var(const secp256k1_int128 *a, con
    return a->hi == b->hi && a->lo == b->lo;
 }
 
-static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n) {
-   VERIFY_CHECK(n < 127);
-   return n >= 64 ? r->hi == (uint64_t)1 << (n - 64) && r->lo == 0
-                  : r->hi == 0 && r->lo == (uint64_t)1 << n;
+static SECP256K1_INLINE int secp256k1_i128_check_pow2(const secp256k1_int128 *r, unsigned int n, int sign) {
+    VERIFY_CHECK(n < 127);
+    VERIFY_CHECK(sign == 1 || sign == -1);
+    return n >= 64 ? r->hi == (uint64_t)sign << (n - 64) && r->lo == 0
+                   : r->hi == (uint64_t)(sign >> 1) && r->lo == (uint64_t)sign << n;
 }
 
 #endif

src/modinv32.h

@@ -7,10 +7,6 @@
 #ifndef SECP256K1_MODINV32_H
 #define SECP256K1_MODINV32_H
 
-#if defined HAVE_CONFIG_H
-#include "libsecp256k1-config.h"
-#endif
-
 #include "util.h"
 
 /* A signed 30-bit limb representation of integers.
@@ -39,4 +35,9 @@ static void secp256k1_modinv32_var(secp256k1_modinv32_signed30 *x, const secp256
 /* Same as secp256k1_modinv32_var, but constant time in x (not in the modulus). */
 static void secp256k1_modinv32(secp256k1_modinv32_signed30 *x, const secp256k1_modinv32_modinfo *modinfo);
 
+/* Compute the Jacobi symbol for (x | modinfo->modulus). x must be coprime with modulus (and thus
+ * cannot be 0, as modulus >= 3). All limbs of x must be non-negative. Returns 0 if the result
+ * cannot be computed. */
+static int secp256k1_jacobi32_maybe_var(const secp256k1_modinv32_signed30 *x, const secp256k1_modinv32_modinfo *modinfo);
+
 #endif /* SECP256K1_MODINV32_H */

src/modinv32_impl.h

@@ -64,7 +64,7 @@ static void secp256k1_modinv32_normalize_30(secp256k1_modinv32_signed30 *r, int3
     const int32_t M30 = (int32_t)(UINT32_MAX >> 2);
     int32_t r0 = r->v[0], r1 = r->v[1], r2 = r->v[2], r3 = r->v[3], r4 = r->v[4],
             r5 = r->v[5], r6 = r->v[6], r7 = r->v[7], r8 = r->v[8];
-    int32_t cond_add, cond_negate;
+    volatile int32_t cond_add, cond_negate;
 
 #ifdef VERIFY
     /* Verify that all limbs are in range (-2^30,2^30). */
@@ -144,7 +144,6 @@ static void secp256k1_modinv32_normalize_30(secp256k1_modinv32_signed30 *r, int3
     r->v[7] = r7;
     r->v[8] = r8;
 
-#ifdef VERIFY
     VERIFY_CHECK(r0 >> 30 == 0);
     VERIFY_CHECK(r1 >> 30 == 0);
     VERIFY_CHECK(r2 >> 30 == 0);
@@ -156,7 +155,6 @@ static void secp256k1_modinv32_normalize_30(secp256k1_modinv32_signed30 *r, int3
     VERIFY_CHECK(r8 >> 30 == 0);
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(r, 9, &modinfo->modulus, 0) >= 0); /* r >= 0 */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(r, 9, &modinfo->modulus, 1) < 0); /* r < modulus */
-#endif
 }
 
 /* Data type for transition matrices (see section 3 of explanation).
@@ -186,7 +184,8 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_
      * being inside [-2^31,2^31) means that casting to signed works correctly.
      */
     uint32_t u = 1, v = 0, q = 0, r = 1;
-    uint32_t c1, c2, f = f0, g = g0, x, y, z;
+    volatile uint32_t c1, c2;
+    uint32_t mask1, mask2, f = f0, g = g0, x, y, z;
     int i;
 
     for (i = 0; i < 30; ++i) {
@@ -195,23 +194,25 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_
         VERIFY_CHECK((q * f0 + r * g0) == g << i);
         /* Compute conditional masks for (zeta < 0) and for (g & 1). */
         c1 = zeta >> 31;
-        c2 = -(g & 1);
+        mask1 = c1;
+        c2 = g & 1;
+        mask2 = -c2;
         /* Compute x,y,z, conditionally negated versions of f,u,v. */
-        x = (f ^ c1) - c1;
-        y = (u ^ c1) - c1;
-        z = (v ^ c1) - c1;
+        x = (f ^ mask1) - mask1;
+        y = (u ^ mask1) - mask1;
+        z = (v ^ mask1) - mask1;
         /* Conditionally add x,y,z to g,q,r. */
-        g += x & c2;
-        q += y & c2;
-        r += z & c2;
-        /* In what follows, c1 is a condition mask for (zeta < 0) and (g & 1). */
-        c1 &= c2;
+        g += x & mask2;
+        q += y & mask2;
+        r += z & mask2;
+        /* In what follows, mask1 is a condition mask for (zeta < 0) and (g & 1). */
+        mask1 &= mask2;
         /* Conditionally change zeta into -zeta-2 or zeta-1. */
-        zeta = (zeta ^ c1) - 1;
+        zeta = (zeta ^ mask1) - 1;
         /* Conditionally add g,q,r to f,u,v. */
-        f += g & c1;
-        u += q & c1;
-        v += r & c1;
+        f += g & mask1;
+        u += q & mask1;
+        v += r & mask1;
         /* Shifts */
         g >>= 1;
         u <<= 1;
@@ -232,6 +233,21 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_
     return zeta;
 }
 
+/* secp256k1_modinv32_inv256[i] = -(2*i+1)^-1 (mod 256) */
+static const uint8_t secp256k1_modinv32_inv256[128] = {
+    0xFF, 0x55, 0x33, 0x49, 0xC7, 0x5D, 0x3B, 0x11, 0x0F, 0xE5, 0xC3, 0x59,
+    0xD7, 0xED, 0xCB, 0x21, 0x1F, 0x75, 0x53, 0x69, 0xE7, 0x7D, 0x5B, 0x31,
+    0x2F, 0x05, 0xE3, 0x79, 0xF7, 0x0D, 0xEB, 0x41, 0x3F, 0x95, 0x73, 0x89,
+    0x07, 0x9D, 0x7B, 0x51, 0x4F, 0x25, 0x03, 0x99, 0x17, 0x2D, 0x0B, 0x61,
+    0x5F, 0xB5, 0x93, 0xA9, 0x27, 0xBD, 0x9B, 0x71, 0x6F, 0x45, 0x23, 0xB9,
+    0x37, 0x4D, 0x2B, 0x81, 0x7F, 0xD5, 0xB3, 0xC9, 0x47, 0xDD, 0xBB, 0x91,
+    0x8F, 0x65, 0x43, 0xD9, 0x57, 0x6D, 0x4B, 0xA1, 0x9F, 0xF5, 0xD3, 0xE9,
+    0x67, 0xFD, 0xDB, 0xB1, 0xAF, 0x85, 0x63, 0xF9, 0x77, 0x8D, 0x6B, 0xC1,
+    0xBF, 0x15, 0xF3, 0x09, 0x87, 0x1D, 0xFB, 0xD1, 0xCF, 0xA5, 0x83, 0x19,
+    0x97, 0xAD, 0x8B, 0xE1, 0xDF, 0x35, 0x13, 0x29, 0xA7, 0x3D, 0x1B, 0xF1,
+    0xEF, 0xC5, 0xA3, 0x39, 0xB7, 0xCD, 0xAB, 0x01
+};
+
 /* Compute the transition matrix and eta for 30 divsteps (variable time).
  *
  * Input:  eta: initial eta
@@ -243,21 +259,6 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_
  * Implements the divsteps_n_matrix_var function from the explanation.
  */
 static int32_t secp256k1_modinv32_divsteps_30_var(int32_t eta, uint32_t f0, uint32_t g0, secp256k1_modinv32_trans2x2 *t) {
-    /* inv256[i] = -(2*i+1)^-1 (mod 256) */
-    static const uint8_t inv256[128] = {
-        0xFF, 0x55, 0x33, 0x49, 0xC7, 0x5D, 0x3B, 0x11, 0x0F, 0xE5, 0xC3, 0x59,
-        0xD7, 0xED, 0xCB, 0x21, 0x1F, 0x75, 0x53, 0x69, 0xE7, 0x7D, 0x5B, 0x31,
-        0x2F, 0x05, 0xE3, 0x79, 0xF7, 0x0D, 0xEB, 0x41, 0x3F, 0x95, 0x73, 0x89,
-        0x07, 0x9D, 0x7B, 0x51, 0x4F, 0x25, 0x03, 0x99, 0x17, 0x2D, 0x0B, 0x61,
-        0x5F, 0xB5, 0x93, 0xA9, 0x27, 0xBD, 0x9B, 0x71, 0x6F, 0x45, 0x23, 0xB9,
-        0x37, 0x4D, 0x2B, 0x81, 0x7F, 0xD5, 0xB3, 0xC9, 0x47, 0xDD, 0xBB, 0x91,
-        0x8F, 0x65, 0x43, 0xD9, 0x57, 0x6D, 0x4B, 0xA1, 0x9F, 0xF5, 0xD3, 0xE9,
-        0x67, 0xFD, 0xDB, 0xB1, 0xAF, 0x85, 0x63, 0xF9, 0x77, 0x8D, 0x6B, 0xC1,
-        0xBF, 0x15, 0xF3, 0x09, 0x87, 0x1D, 0xFB, 0xD1, 0xCF, 0xA5, 0x83, 0x19,
-        0x97, 0xAD, 0x8B, 0xE1, 0xDF, 0x35, 0x13, 0x29, 0xA7, 0x3D, 0x1B, 0xF1,
-        0xEF, 0xC5, 0xA3, 0x39, 0xB7, 0xCD, 0xAB, 0x01
-    };
-
     /* Transformation matrix; see comments in secp256k1_modinv32_divsteps_30. */
     uint32_t u = 1, v = 0, q = 0, r = 1;
     uint32_t f = f0, g = g0, m;
@@ -297,7 +298,7 @@ static int32_t secp256k1_modinv32_divsteps_30_var(int32_t eta, uint32_t f0, uint
         VERIFY_CHECK(limit > 0 && limit <= 30);
         m = (UINT32_MAX >> (32 - limit)) & 255U;
         /* Find what multiple of f must be added to g to cancel its bottom min(limit, 8) bits. */
-        w = (g * inv256[(f >> 1) & 127]) & m;
+        w = (g * secp256k1_modinv32_inv256[(f >> 1) & 127]) & m;
         /* Do so. */
         g += f * w;
         q += u * w;
@@ -317,6 +318,86 @@ static int32_t secp256k1_modinv32_divsteps_30_var(int32_t eta, uint32_t f0, uint
     return eta;
 }
 
+/* Compute the transition matrix and eta for 30 posdivsteps (variable time, eta=-delta), and keeps track
+ * of the Jacobi symbol along the way. f0 and g0 must be f and g mod 2^32 rather than 2^30, because
+ * Jacobi tracking requires knowing (f mod 8) rather than just (f mod 2).
+ *
+ * Input:        eta: initial eta
+ *               f0:  bottom limb of initial f
+ *               g0:  bottom limb of initial g
+ * Output:       t: transition matrix
+ * Input/Output: (*jacp & 1) is bitflipped if and only if the Jacobi symbol of (f | g) changes sign
+ *               by applying the returned transformation matrix to it. The other bits of *jacp may
+ *               change, but are meaningless.
+ * Return: final eta
+ */
+static int32_t secp256k1_modinv32_posdivsteps_30_var(int32_t eta, uint32_t f0, uint32_t g0, secp256k1_modinv32_trans2x2 *t, int *jacp) {
+    /* Transformation matrix. */
+    uint32_t u = 1, v = 0, q = 0, r = 1;
+    uint32_t f = f0, g = g0, m;
+    uint16_t w;
+    int i = 30, limit, zeros;
+    int jac = *jacp;
+
+    for (;;) {
+        /* Use a sentinel bit to count zeros only up to i. */
+        zeros = secp256k1_ctz32_var(g | (UINT32_MAX << i));
+        /* Perform zeros divsteps at once; they all just divide g by two. */
+        g >>= zeros;
+        u <<= zeros;
+        v <<= zeros;
+        eta -= zeros;
+        i -= zeros;
+        /* Update the bottom bit of jac: when dividing g by an odd power of 2,
+         * if (f mod 8) is 3 or 5, the Jacobi symbol changes sign. */
+        jac ^= (zeros & ((f >> 1) ^ (f >> 2)));
+        /* We're done once we've done 30 posdivsteps. */
+        if (i == 0) break;
+        VERIFY_CHECK((f & 1) == 1);
+        VERIFY_CHECK((g & 1) == 1);
+        VERIFY_CHECK((u * f0 + v * g0) == f << (30 - i));
+        VERIFY_CHECK((q * f0 + r * g0) == g << (30 - i));
+        /* If eta is negative, negate it and replace f,g with g,f. */
+        if (eta < 0) {
+            uint32_t tmp;
+            eta = -eta;
+            /* Update bottom bit of jac: when swapping f and g, the Jacobi symbol changes sign
+             * if both f and g are 3 mod 4. */
+            jac ^= ((f & g) >> 1);
+            tmp = f; f = g; g = tmp;
+            tmp = u; u = q; q = tmp;
+            tmp = v; v = r; r = tmp;
+        }
+        /* eta is now >= 0. In what follows we're going to cancel out the bottom bits of g. No more
+         * than i can be cancelled out (as we'd be done before that point), and no more than eta+1
+         * can be done as its sign will flip once that happens. */
+        limit = ((int)eta + 1) > i ? i : ((int)eta + 1);
+        /* m is a mask for the bottom min(limit, 8) bits (our table only supports 8 bits). */
+        VERIFY_CHECK(limit > 0 && limit <= 30);
+        m = (UINT32_MAX >> (32 - limit)) & 255U;
+        /* Find what multiple of f must be added to g to cancel its bottom min(limit, 8) bits. */
+        w = (g * secp256k1_modinv32_inv256[(f >> 1) & 127]) & m;
+        /* Do so. */
+        g += f * w;
+        q += u * w;
+        r += v * w;
+        VERIFY_CHECK((g & m) == 0);
+    }
+    /* Return data in t and return value. */
+    t->u = (int32_t)u;
+    t->v = (int32_t)v;
+    t->q = (int32_t)q;
+    t->r = (int32_t)r;
+    /* The determinant of t must be a power of two. This guarantees that multiplication with t
+     * does not change the gcd of f and g, apart from adding a power-of-2 factor to it (which
+     * will be divided out again). As each divstep's individual matrix has determinant 2 or -2,
+     * the aggregate of 30 of them will have determinant 2^30 or -2^30. */
+    VERIFY_CHECK((int64_t)t->u * t->r - (int64_t)t->v * t->q == ((int64_t)1) << 30 ||
+                 (int64_t)t->u * t->r - (int64_t)t->v * t->q == -(((int64_t)1) << 30));
+    *jacp = jac;
+    return eta;
+}
+
 /* Compute (t/2^30) * [d, e] mod modulus, where t is a transition matrix for 30 divsteps.
  *
  * On input and output, d and e are in range (-2*modulus,modulus). All output limbs will be in range
@@ -330,16 +411,13 @@ static void secp256k1_modinv32_update_de_30(secp256k1_modinv32_signed30 *d, secp
     int32_t di, ei, md, me, sd, se;
     int64_t cd, ce;
     int i;
-#ifdef VERIFY
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(d, 9, &modinfo->modulus, -2) > 0); /* d > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(d, 9, &modinfo->modulus, 1) < 0);  /* d <    modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, 1) < 0);  /* e <    modulus */
-    VERIFY_CHECK((labs(u) + labs(v)) >= 0); /* |u|+|v| doesn't overflow */
-    VERIFY_CHECK((labs(q) + labs(r)) >= 0); /* |q|+|r| doesn't overflow */
-    VERIFY_CHECK((labs(u) + labs(v)) <= M30 + 1); /* |u|+|v| <= 2^30 */
-    VERIFY_CHECK((labs(q) + labs(r)) <= M30 + 1); /* |q|+|r| <= 2^30 */
-#endif
+    VERIFY_CHECK(labs(u) <= (M30 + 1 - labs(v))); /* |u|+|v| <= 2^30 */
+    VERIFY_CHECK(labs(q) <= (M30 + 1 - labs(r))); /* |q|+|r| <= 2^30 */
+
     /* [md,me] start as zero; plus [u,q] if d is negative; plus [v,r] if e is negative. */
     sd = d->v[8] >> 31;
     se = e->v[8] >> 31;
@@ -374,12 +452,11 @@ static void secp256k1_modinv32_update_de_30(secp256k1_modinv32_signed30 *d, secp
     /* What remains is limb 9 of t*[d,e]+modulus*[md,me]; store it as output limb 8. */
     d->v[8] = (int32_t)cd;
     e->v[8] = (int32_t)ce;
-#ifdef VERIFY
+
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(d, 9, &modinfo->modulus, -2) > 0); /* d > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(d, 9, &modinfo->modulus, 1) < 0);  /* d <    modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, 1) < 0);  /* e <    modulus */
-#endif
 }
 
 /* Compute (t/2^30) * [f, g], where t is a transition matrix for 30 divsteps.
@@ -469,25 +546,23 @@ static void secp256k1_modinv32(secp256k1_modinv32_signed30 *x, const secp256k1_m
         /* Update d,e using that transition matrix. */
         secp256k1_modinv32_update_de_30(&d, &e, &t, modinfo);
         /* Update f,g using that transition matrix. */
-#ifdef VERIFY
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, 9, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, 9, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
+
         secp256k1_modinv32_update_fg_30(&f, &g, &t);
-#ifdef VERIFY
+
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, 9, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, 9, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
     }
 
     /* At this point sufficient iterations have been performed that g must have reached 0
      * and (if g was not originally 0) f must now equal +/- GCD of the initial f, g
      * values i.e. +/- 1, and d now contains +/- the modular inverse. */
-#ifdef VERIFY
+
     /* g == 0 */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, 9, &SECP256K1_SIGNED30_ONE, 0) == 0);
     /* |f| == 1, or (x == 0 and d == 0 and |f|=modulus) */
@@ -497,7 +572,6 @@ static void secp256k1_modinv32(secp256k1_modinv32_signed30 *x, const secp256k1_m
                   secp256k1_modinv32_mul_cmp_30(&d, 9, &SECP256K1_SIGNED30_ONE, 0) == 0 &&
                   (secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, 1) == 0 ||
                    secp256k1_modinv32_mul_cmp_30(&f, 9, &modinfo->modulus, -1) == 0)));
-#endif
 
     /* Optionally negate d, normalize to [0,modulus), and return it. */
     secp256k1_modinv32_normalize_30(&d, f.v[8], modinfo);
@@ -526,12 +600,12 @@ static void secp256k1_modinv32_var(secp256k1_modinv32_signed30 *x, const secp256
         /* Update d,e using that transition matrix. */
         secp256k1_modinv32_update_de_30(&d, &e, &t, modinfo);
         /* Update f,g using that transition matrix. */
-#ifdef VERIFY
+
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
+
         secp256k1_modinv32_update_fg_30_var(len, &f, &g, &t);
         /* If the bottom limb of g is 0, there is a chance g=0. */
         if (g.v[0] == 0) {
@@ -556,18 +630,17 @@ static void secp256k1_modinv32_var(secp256k1_modinv32_signed30 *x, const secp256
             g.v[len - 2] |= (uint32_t)gn << 30;
             --len;
         }
-#ifdef VERIFY
+
         VERIFY_CHECK(++i < 25); /* We should never need more than 25*30 = 750 divsteps */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
     }
 
     /* At this point g is 0 and (if g was not originally 0) f must now equal +/- GCD of
      * the initial f, g values i.e. +/- 1, and d now contains +/- the modular inverse. */
-#ifdef VERIFY
+
     /* g == 0 */
     VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &SECP256K1_SIGNED30_ONE, 0) == 0);
     /* |f| == 1, or (x == 0 and d == 0 and |f|=modulus) */
@@ -577,11 +650,78 @@ static void secp256k1_modinv32_var(secp256k1_modinv32_signed30 *x, const secp256
                   secp256k1_modinv32_mul_cmp_30(&d, 9, &SECP256K1_SIGNED30_ONE, 0) == 0 &&
                   (secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 1) == 0 ||
                    secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, -1) == 0)));
-#endif
 
     /* Optionally negate d, normalize to [0,modulus), and return it. */
     secp256k1_modinv32_normalize_30(&d, f.v[len - 1], modinfo);
     *x = d;
 }
 
+/* Do up to 50 iterations of 30 posdivsteps (up to 1500 steps; more is extremely rare) each until f=1.
+ * In VERIFY mode use a lower number of iterations (750, close to the median 756), so failure actually occurs. */
+#ifdef VERIFY
+#define JACOBI32_ITERATIONS 25
+#else
+#define JACOBI32_ITERATIONS 50
+#endif
+
+/* Compute the Jacobi symbol of x modulo modinfo->modulus (variable time). gcd(x,modulus) must be 1. */
+static int secp256k1_jacobi32_maybe_var(const secp256k1_modinv32_signed30 *x, const secp256k1_modinv32_modinfo *modinfo) {
+    /* Start with f=modulus, g=x, eta=-1. */
+    secp256k1_modinv32_signed30 f = modinfo->modulus;
+    secp256k1_modinv32_signed30 g = *x;
+    int j, len = 9;
+    int32_t eta = -1; /* eta = -delta; delta is initially 1 */
+    int32_t cond, fn, gn;
+    int jac = 0;
+    int count;
+
+    /* The input limbs must all be non-negative. */
+    VERIFY_CHECK(g.v[0] >= 0 && g.v[1] >= 0 && g.v[2] >= 0 && g.v[3] >= 0 && g.v[4] >= 0 && g.v[5] >= 0 && g.v[6] >= 0 && g.v[7] >= 0 && g.v[8] >= 0);
+
+    /* If x > 0, then if the loop below converges, it converges to f=g=gcd(x,modulus). Since we
+     * require that gcd(x,modulus)=1 and modulus>=3, x cannot be 0. Thus, we must reach f=1 (or
+     * time out). */
+    VERIFY_CHECK((g.v[0] | g.v[1] | g.v[2] | g.v[3] | g.v[4] | g.v[5] | g.v[6] | g.v[7] | g.v[8]) != 0);
+
+    for (count = 0; count < JACOBI32_ITERATIONS; ++count) {
+        /* Compute transition matrix and new eta after 30 posdivsteps. */
+        secp256k1_modinv32_trans2x2 t;
+        eta = secp256k1_modinv32_posdivsteps_30_var(eta, f.v[0] | ((uint32_t)f.v[1] << 30), g.v[0] | ((uint32_t)g.v[1] << 30), &t, &jac);
+        /* Update f,g using that transition matrix. */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 0) > 0); /* f > 0 */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 0) > 0); /* g > 0 */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 1) < 0);  /* g < modulus */
+
+        secp256k1_modinv32_update_fg_30_var(len, &f, &g, &t);
+        /* If the bottom limb of f is 1, there is a chance that f=1. */
+        if (f.v[0] == 1) {
+            cond = 0;
+            /* Check if the other limbs are also 0. */
+            for (j = 1; j < len; ++j) {
+                cond |= f.v[j];
+            }
+            /* If so, we're done. If f=1, the Jacobi symbol (g | f)=1. */
+            if (cond == 0) return 1 - 2*(jac & 1);
+        }
+
+        /* Determine if len>1 and limb (len-1) of both f and g is 0. */
+        fn = f.v[len - 1];
+        gn = g.v[len - 1];
+        cond = ((int32_t)len - 2) >> 31;
+        cond |= fn;
+        cond |= gn;
+        /* If so, reduce length. */
+        if (cond == 0) --len;
+
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 0) > 0); /* f > 0 */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 0) > 0); /* g > 0 */
+        VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(&g, len, &modinfo->modulus, 1) < 0);  /* g < modulus */
+    }
+
+    /* The loop failed to converge to f=g after 1500 iterations. Return 0, indicating unknown result. */
+    return 0;
+}
+
 #endif /* SECP256K1_MODINV32_IMPL_H */

src/modinv64.h

@@ -7,10 +7,6 @@
 #ifndef SECP256K1_MODINV64_H
 #define SECP256K1_MODINV64_H
 
-#if defined HAVE_CONFIG_H
-#include "libsecp256k1-config.h"
-#endif
-
 #include "util.h"
 
 #ifndef SECP256K1_WIDEMUL_INT128
@@ -43,4 +39,9 @@ static void secp256k1_modinv64_var(secp256k1_modinv64_signed62 *x, const secp256
 /* Same as secp256k1_modinv64_var, but constant time in x (not in the modulus). */
 static void secp256k1_modinv64(secp256k1_modinv64_signed62 *x, const secp256k1_modinv64_modinfo *modinfo);
 
+/* Compute the Jacobi symbol for (x | modinfo->modulus). x must be coprime with modulus (and thus
+ * cannot be 0, as modulus >= 3). All limbs of x must be non-negative. Returns 0 if the result
+ * cannot be computed. */
+static int secp256k1_jacobi64_maybe_var(const secp256k1_modinv64_signed62 *x, const secp256k1_modinv64_modinfo *modinfo);
+
 #endif /* SECP256K1_MODINV64_H */

src/modinv64_impl.h

@@ -39,13 +39,13 @@ static const secp256k1_modinv64_signed62 SECP256K1_SIGNED62_ONE = {{1}};
 
 /* Compute a*factor and put it in r. All but the top limb in r will be in range [0,2^62). */
 static void secp256k1_modinv64_mul_62(secp256k1_modinv64_signed62 *r, const secp256k1_modinv64_signed62 *a, int alen, int64_t factor) {
-    const int64_t M62 = (int64_t)(UINT64_MAX >> 2);
+    const uint64_t M62 = UINT64_MAX >> 2;
     secp256k1_int128 c, d;
     int i;
     secp256k1_i128_from_i64(&c, 0);
     for (i = 0; i < 4; ++i) {
         if (i < alen) secp256k1_i128_accum_mul(&c, a->v[i], factor);
-        r->v[i] = secp256k1_i128_to_i64(&c) & M62; secp256k1_i128_rshift(&c, 62);
+        r->v[i] = secp256k1_i128_to_u64(&c) & M62; secp256k1_i128_rshift(&c, 62);
     }
     if (4 < alen) secp256k1_i128_accum_mul(&c, a->v[4], factor);
     secp256k1_i128_from_i64(&d, secp256k1_i128_to_i64(&c));
@@ -71,11 +71,13 @@ static int secp256k1_modinv64_mul_cmp_62(const secp256k1_modinv64_signed62 *a, i
     return 0;
 }
 
-/* Check if the determinant of t is equal to 1 << n. */
-static int secp256k1_modinv64_det_check_pow2(const secp256k1_modinv64_trans2x2 *t, unsigned int n) {
+/* Check if the determinant of t is equal to 1 << n. If abs, check if |det t| == 1 << n. */
+static int secp256k1_modinv64_det_check_pow2(const secp256k1_modinv64_trans2x2 *t, unsigned int n, int abs) {
     secp256k1_int128 a;
     secp256k1_i128_det(&a, t->u, t->v, t->q, t->r);
-    return secp256k1_i128_check_pow2(&a, n);
+    if (secp256k1_i128_check_pow2(&a, n, 1)) return 1;
+    if (abs && secp256k1_i128_check_pow2(&a, n, -1)) return 1;
+    return 0;
 }
 #endif
 
@@ -86,7 +88,7 @@ static int secp256k1_modinv64_det_check_pow2(const secp256k1_modinv64_trans2x2 *
 static void secp256k1_modinv64_normalize_62(secp256k1_modinv64_signed62 *r, int64_t sign, const secp256k1_modinv64_modinfo *modinfo) {
     const int64_t M62 = (int64_t)(UINT64_MAX >> 2);
     int64_t r0 = r->v[0], r1 = r->v[1], r2 = r->v[2], r3 = r->v[3], r4 = r->v[4];
-    int64_t cond_add, cond_negate;
+    volatile int64_t cond_add, cond_negate;
 
 #ifdef VERIFY
     /* Verify that all limbs are in range (-2^62,2^62). */
@@ -142,7 +144,6 @@ static void secp256k1_modinv64_normalize_62(secp256k1_modinv64_signed62 *r, int6
     r->v[3] = r3;
     r->v[4] = r4;
 
-#ifdef VERIFY
     VERIFY_CHECK(r0 >> 62 == 0);
     VERIFY_CHECK(r1 >> 62 == 0);
     VERIFY_CHECK(r2 >> 62 == 0);
@@ -150,7 +151,6 @@ static void secp256k1_modinv64_normalize_62(secp256k1_modinv64_signed62 *r, int6
     VERIFY_CHECK(r4 >> 62 == 0);
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(r, 5, &modinfo->modulus, 0) >= 0); /* r >= 0 */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(r, 5, &modinfo->modulus, 1) < 0); /* r < modulus */
-#endif
 }
 
 /* Compute the transition matrix and eta for 59 divsteps (where zeta=-(delta+1/2)).
@@ -173,7 +173,8 @@ static int64_t secp256k1_modinv64_divsteps_59(int64_t zeta, uint64_t f0, uint64_
      * being inside [-2^63,2^63) means that casting to signed works correctly.
      */
     uint64_t u = 8, v = 0, q = 0, r = 8;
-    uint64_t c1, c2, f = f0, g = g0, x, y, z;
+    volatile uint64_t c1, c2;
+    uint64_t mask1, mask2, f = f0, g = g0, x, y, z;
     int i;
 
     for (i = 3; i < 62; ++i) {
@@ -182,23 +183,25 @@ static int64_t secp256k1_modinv64_divsteps_59(int64_t zeta, uint64_t f0, uint64_
         VERIFY_CHECK((q * f0 + r * g0) == g << i);
         /* Compute conditional masks for (zeta < 0) and for (g & 1). */
         c1 = zeta >> 63;
-        c2 = -(g & 1);
+        mask1 = c1;
+        c2 = g & 1;
+        mask2 = -c2;
         /* Compute x,y,z, conditionally negated versions of f,u,v. */
-        x = (f ^ c1) - c1;
-        y = (u ^ c1) - c1;
-        z = (v ^ c1) - c1;
+        x = (f ^ mask1) - mask1;
+        y = (u ^ mask1) - mask1;
+        z = (v ^ mask1) - mask1;
         /* Conditionally add x,y,z to g,q,r. */
-        g += x & c2;
-        q += y & c2;
-        r += z & c2;
+        g += x & mask2;
+        q += y & mask2;
+        r += z & mask2;
         /* In what follows, c1 is a condition mask for (zeta < 0) and (g & 1). */
-        c1 &= c2;
+        mask1 &= mask2;
         /* Conditionally change zeta into -zeta-2 or zeta-1. */
-        zeta = (zeta ^ c1) - 1;
+        zeta = (zeta ^ mask1) - 1;
         /* Conditionally add g,q,r to f,u,v. */
-        f += g & c1;
-        u += q & c1;
-        v += r & c1;
+        f += g & mask1;
+        u += q & mask1;
+        v += r & mask1;
         /* Shifts */
         g >>= 1;
         u <<= 1;
@@ -211,15 +214,15 @@ static int64_t secp256k1_modinv64_divsteps_59(int64_t zeta, uint64_t f0, uint64_
     t->v = (int64_t)v;
     t->q = (int64_t)q;
     t->r = (int64_t)r;
-#ifdef VERIFY
+
     /* The determinant of t must be a power of two. This guarantees that multiplication with t
      * does not change the gcd of f and g, apart from adding a power-of-2 factor to it (which
      * will be divided out again). As each divstep's individual matrix has determinant 2, the
      * aggregate of 59 of them will have determinant 2^59. Multiplying with the initial
      * 8*identity (which has determinant 2^6) means the overall outputs has determinant
      * 2^65. */
-    VERIFY_CHECK(secp256k1_modinv64_det_check_pow2(t, 65));
-#endif
+    VERIFY_CHECK(secp256k1_modinv64_det_check_pow2(t, 65, 0));
+
     return zeta;
 }
 
@@ -266,7 +269,7 @@ static int64_t secp256k1_modinv64_divsteps_62_var(int64_t eta, uint64_t f0, uint
             tmp = v; v = r; r = -tmp;
             /* Use a formula to cancel out up to 6 bits of g. Also, no more than i can be cancelled
              * out (as we'd be done before that point), and no more than eta+1 can be done as its
-             * will flip again once that happens. */
+             * sign will flip again once that happens. */
             limit = ((int)eta + 1) > i ? i : ((int)eta + 1);
             VERIFY_CHECK(limit > 0 && limit <= 62);
             /* m is a mask for the bottom min(limit, 6) bits. */
@@ -296,13 +299,105 @@ static int64_t secp256k1_modinv64_divsteps_62_var(int64_t eta, uint64_t f0, uint
     t->v = (int64_t)v;
     t->q = (int64_t)q;
     t->r = (int64_t)r;
-#ifdef VERIFY
+
     /* The determinant of t must be a power of two. This guarantees that multiplication with t
      * does not change the gcd of f and g, apart from adding a power-of-2 factor to it (which
      * will be divided out again). As each divstep's individual matrix has determinant 2, the
      * aggregate of 62 of them will have determinant 2^62. */
-    VERIFY_CHECK(secp256k1_modinv64_det_check_pow2(t, 62));
-#endif
+    VERIFY_CHECK(secp256k1_modinv64_det_check_pow2(t, 62, 0));
+
+    return eta;
+}
+
+/* Compute the transition matrix and eta for 62 posdivsteps (variable time, eta=-delta), and keeps track
+ * of the Jacobi symbol along the way. f0 and g0 must be f and g mod 2^64 rather than 2^62, because
+ * Jacobi tracking requires knowing (f mod 8) rather than just (f mod 2).
+ *
+ * Input:        eta: initial eta
+ *               f0:  bottom limb of initial f
+ *               g0:  bottom limb of initial g
+ * Output:       t: transition matrix
+ * Input/Output: (*jacp & 1) is bitflipped if and only if the Jacobi symbol of (f | g) changes sign
+ *               by applying the returned transformation matrix to it. The other bits of *jacp may
+ *               change, but are meaningless.
+ * Return:       final eta
+ */
+static int64_t secp256k1_modinv64_posdivsteps_62_var(int64_t eta, uint64_t f0, uint64_t g0, secp256k1_modinv64_trans2x2 *t, int *jacp) {
+    /* Transformation matrix; see comments in secp256k1_modinv64_divsteps_62. */
+    uint64_t u = 1, v = 0, q = 0, r = 1;
+    uint64_t f = f0, g = g0, m;
+    uint32_t w;
+    int i = 62, limit, zeros;
+    int jac = *jacp;
+
+    for (;;) {
+        /* Use a sentinel bit to count zeros only up to i. */
+        zeros = secp256k1_ctz64_var(g | (UINT64_MAX << i));
+        /* Perform zeros divsteps at once; they all just divide g by two. */
+        g >>= zeros;
+        u <<= zeros;
+        v <<= zeros;
+        eta -= zeros;
+        i -= zeros;
+        /* Update the bottom bit of jac: when dividing g by an odd power of 2,
+         * if (f mod 8) is 3 or 5, the Jacobi symbol changes sign. */
+        jac ^= (zeros & ((f >> 1) ^ (f >> 2)));
+        /* We're done once we've done 62 posdivsteps. */
+        if (i == 0) break;
+        VERIFY_CHECK((f & 1) == 1);
+        VERIFY_CHECK((g & 1) == 1);
+        VERIFY_CHECK((u * f0 + v * g0) == f << (62 - i));
+        VERIFY_CHECK((q * f0 + r * g0) == g << (62 - i));
+        /* If eta is negative, negate it and replace f,g with g,f. */
+        if (eta < 0) {
+            uint64_t tmp;
+            eta = -eta;
+            tmp = f; f = g; g = tmp;
+            tmp = u; u = q; q = tmp;
+            tmp = v; v = r; r = tmp;
+            /* Update bottom bit of jac: when swapping f and g, the Jacobi symbol changes sign
+             * if both f and g are 3 mod 4. */
+            jac ^= ((f & g) >> 1);
+            /* Use a formula to cancel out up to 6 bits of g. Also, no more than i can be cancelled
+             * out (as we'd be done before that point), and no more than eta+1 can be done as its
+             * sign will flip again once that happens. */
+            limit = ((int)eta + 1) > i ? i : ((int)eta + 1);
+            VERIFY_CHECK(limit > 0 && limit <= 62);
+            /* m is a mask for the bottom min(limit, 6) bits. */
+            m = (UINT64_MAX >> (64 - limit)) & 63U;
+            /* Find what multiple of f must be added to g to cancel its bottom min(limit, 6)
+             * bits. */
+            w = (f * g * (f * f - 2)) & m;
+        } else {
+            /* In this branch, use a simpler formula that only lets us cancel up to 4 bits of g, as
+             * eta tends to be smaller here. */
+            limit = ((int)eta + 1) > i ? i : ((int)eta + 1);
+            VERIFY_CHECK(limit > 0 && limit <= 62);
+            /* m is a mask for the bottom min(limit, 4) bits. */
+            m = (UINT64_MAX >> (64 - limit)) & 15U;
+            /* Find what multiple of f must be added to g to cancel its bottom min(limit, 4)
+             * bits. */
+            w = f + (((f + 1) & 4) << 1);
+            w = (-w * g) & m;
+        }
+        g += f * w;
+        q += u * w;
+        r += v * w;
+        VERIFY_CHECK((g & m) == 0);
+    }
+    /* Return data in t and return value. */
+    t->u = (int64_t)u;
+    t->v = (int64_t)v;
+    t->q = (int64_t)q;
+    t->r = (int64_t)r;
+
+    /* The determinant of t must be a power of two. This guarantees that multiplication with t
+     * does not change the gcd of f and g, apart from adding a power-of-2 factor to it (which
+     * will be divided out again). As each divstep's individual matrix has determinant 2 or -2,
+     * the aggregate of 62 of them will have determinant 2^62 or -2^62. */
+    VERIFY_CHECK(secp256k1_modinv64_det_check_pow2(t, 62, 1));
+
+    *jacp = jac;
     return eta;
 }
 
@@ -314,22 +409,19 @@ static int64_t secp256k1_modinv64_divsteps_62_var(int64_t eta, uint64_t f0, uint
  * This implements the update_de function from the explanation.
  */
 static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp256k1_modinv64_signed62 *e, const secp256k1_modinv64_trans2x2 *t, const secp256k1_modinv64_modinfo* modinfo) {
-    const int64_t M62 = (int64_t)(UINT64_MAX >> 2);
+    const uint64_t M62 = UINT64_MAX >> 2;
     const int64_t d0 = d->v[0], d1 = d->v[1], d2 = d->v[2], d3 = d->v[3], d4 = d->v[4];
     const int64_t e0 = e->v[0], e1 = e->v[1], e2 = e->v[2], e3 = e->v[3], e4 = e->v[4];
     const int64_t u = t->u, v = t->v, q = t->q, r = t->r;
     int64_t md, me, sd, se;
     secp256k1_int128 cd, ce;
-#ifdef VERIFY
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(d, 5, &modinfo->modulus, -2) > 0); /* d > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(d, 5, &modinfo->modulus, 1) < 0);  /* d <    modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, 1) < 0);  /* e <    modulus */
-    VERIFY_CHECK((secp256k1_modinv64_abs(u) + secp256k1_modinv64_abs(v)) >= 0); /* |u|+|v| doesn't overflow */
-    VERIFY_CHECK((secp256k1_modinv64_abs(q) + secp256k1_modinv64_abs(r)) >= 0); /* |q|+|r| doesn't overflow */
-    VERIFY_CHECK((secp256k1_modinv64_abs(u) + secp256k1_modinv64_abs(v)) <= M62 + 1); /* |u|+|v| <= 2^62 */
-    VERIFY_CHECK((secp256k1_modinv64_abs(q) + secp256k1_modinv64_abs(r)) <= M62 + 1); /* |q|+|r| <= 2^62 */
-#endif
+    VERIFY_CHECK(secp256k1_modinv64_abs(u) <= (((int64_t)1 << 62) - secp256k1_modinv64_abs(v))); /* |u|+|v| <= 2^62 */
+    VERIFY_CHECK(secp256k1_modinv64_abs(q) <= (((int64_t)1 << 62) - secp256k1_modinv64_abs(r))); /* |q|+|r| <= 2^62 */
+
     /* [md,me] start as zero; plus [u,q] if d is negative; plus [v,r] if e is negative. */
     sd = d4 >> 63;
     se = e4 >> 63;
@@ -341,14 +433,14 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
     secp256k1_i128_mul(&ce, q, d0);
     secp256k1_i128_accum_mul(&ce, r, e0);
     /* Correct md,me so that t*[d,e]+modulus*[md,me] has 62 zero bottom bits. */
-    md -= (modinfo->modulus_inv62 * (uint64_t)secp256k1_i128_to_i64(&cd) + md) & M62;
-    me -= (modinfo->modulus_inv62 * (uint64_t)secp256k1_i128_to_i64(&ce) + me) & M62;
+    md -= (modinfo->modulus_inv62 * secp256k1_i128_to_u64(&cd) + md) & M62;
+    me -= (modinfo->modulus_inv62 * secp256k1_i128_to_u64(&ce) + me) & M62;
     /* Update the beginning of computation for t*[d,e]+modulus*[md,me] now md,me are known. */
     secp256k1_i128_accum_mul(&cd, modinfo->modulus.v[0], md);
     secp256k1_i128_accum_mul(&ce, modinfo->modulus.v[0], me);
     /* Verify that the low 62 bits of the computation are indeed zero, and then throw them away. */
-    VERIFY_CHECK((secp256k1_i128_to_i64(&cd) & M62) == 0); secp256k1_i128_rshift(&cd, 62);
-    VERIFY_CHECK((secp256k1_i128_to_i64(&ce) & M62) == 0); secp256k1_i128_rshift(&ce, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&cd) & M62) == 0); secp256k1_i128_rshift(&cd, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&ce) & M62) == 0); secp256k1_i128_rshift(&ce, 62);
     /* Compute limb 1 of t*[d,e]+modulus*[md,me], and store it as output limb 0 (= down shift). */
     secp256k1_i128_accum_mul(&cd, u, d1);
     secp256k1_i128_accum_mul(&cd, v, e1);
@@ -358,8 +450,8 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
         secp256k1_i128_accum_mul(&cd, modinfo->modulus.v[1], md);
         secp256k1_i128_accum_mul(&ce, modinfo->modulus.v[1], me);
     }
-    d->v[0] = secp256k1_i128_to_i64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
-    e->v[0] = secp256k1_i128_to_i64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
+    d->v[0] = secp256k1_i128_to_u64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
+    e->v[0] = secp256k1_i128_to_u64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
     /* Compute limb 2 of t*[d,e]+modulus*[md,me], and store it as output limb 1. */
     secp256k1_i128_accum_mul(&cd, u, d2);
     secp256k1_i128_accum_mul(&cd, v, e2);
@@ -369,8 +461,8 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
         secp256k1_i128_accum_mul(&cd, modinfo->modulus.v[2], md);
         secp256k1_i128_accum_mul(&ce, modinfo->modulus.v[2], me);
     }
-    d->v[1] = secp256k1_i128_to_i64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
-    e->v[1] = secp256k1_i128_to_i64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
+    d->v[1] = secp256k1_i128_to_u64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
+    e->v[1] = secp256k1_i128_to_u64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
     /* Compute limb 3 of t*[d,e]+modulus*[md,me], and store it as output limb 2. */
     secp256k1_i128_accum_mul(&cd, u, d3);
     secp256k1_i128_accum_mul(&cd, v, e3);
@@ -380,8 +472,8 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
         secp256k1_i128_accum_mul(&cd, modinfo->modulus.v[3], md);
         secp256k1_i128_accum_mul(&ce, modinfo->modulus.v[3], me);
     }
-    d->v[2] = secp256k1_i128_to_i64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
-    e->v[2] = secp256k1_i128_to_i64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
+    d->v[2] = secp256k1_i128_to_u64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
+    e->v[2] = secp256k1_i128_to_u64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
     /* Compute limb 4 of t*[d,e]+modulus*[md,me], and store it as output limb 3. */
     secp256k1_i128_accum_mul(&cd, u, d4);
     secp256k1_i128_accum_mul(&cd, v, e4);
@@ -389,17 +481,16 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
     secp256k1_i128_accum_mul(&ce, r, e4);
     secp256k1_i128_accum_mul(&cd, modinfo->modulus.v[4], md);
     secp256k1_i128_accum_mul(&ce, modinfo->modulus.v[4], me);
-    d->v[3] = secp256k1_i128_to_i64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
-    e->v[3] = secp256k1_i128_to_i64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
+    d->v[3] = secp256k1_i128_to_u64(&cd) & M62; secp256k1_i128_rshift(&cd, 62);
+    e->v[3] = secp256k1_i128_to_u64(&ce) & M62; secp256k1_i128_rshift(&ce, 62);
     /* What remains is limb 5 of t*[d,e]+modulus*[md,me]; store it as output limb 4. */
     d->v[4] = secp256k1_i128_to_i64(&cd);
     e->v[4] = secp256k1_i128_to_i64(&ce);
-#ifdef VERIFY
+
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(d, 5, &modinfo->modulus, -2) > 0); /* d > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(d, 5, &modinfo->modulus, 1) < 0);  /* d <    modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, 1) < 0);  /* e <    modulus */
-#endif
 }
 
 /* Compute (t/2^62) * [f, g], where t is a transition matrix scaled by 2^62.
@@ -407,7 +498,7 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
  * This implements the update_fg function from the explanation.
  */
 static void secp256k1_modinv64_update_fg_62(secp256k1_modinv64_signed62 *f, secp256k1_modinv64_signed62 *g, const secp256k1_modinv64_trans2x2 *t) {
-    const int64_t M62 = (int64_t)(UINT64_MAX >> 2);
+    const uint64_t M62 = UINT64_MAX >> 2;
     const int64_t f0 = f->v[0], f1 = f->v[1], f2 = f->v[2], f3 = f->v[3], f4 = f->v[4];
     const int64_t g0 = g->v[0], g1 = g->v[1], g2 = g->v[2], g3 = g->v[3], g4 = g->v[4];
     const int64_t u = t->u, v = t->v, q = t->q, r = t->r;
@@ -418,36 +509,36 @@ static void secp256k1_modinv64_update_fg_62(secp256k1_modinv64_signed62 *f, secp
     secp256k1_i128_mul(&cg, q, f0);
     secp256k1_i128_accum_mul(&cg, r, g0);
     /* Verify that the bottom 62 bits of the result are zero, and then throw them away. */
-    VERIFY_CHECK((secp256k1_i128_to_i64(&cf) & M62) == 0); secp256k1_i128_rshift(&cf, 62);
-    VERIFY_CHECK((secp256k1_i128_to_i64(&cg) & M62) == 0); secp256k1_i128_rshift(&cg, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&cf) & M62) == 0); secp256k1_i128_rshift(&cf, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&cg) & M62) == 0); secp256k1_i128_rshift(&cg, 62);
     /* Compute limb 1 of t*[f,g], and store it as output limb 0 (= down shift). */
     secp256k1_i128_accum_mul(&cf, u, f1);
     secp256k1_i128_accum_mul(&cf, v, g1);
     secp256k1_i128_accum_mul(&cg, q, f1);
     secp256k1_i128_accum_mul(&cg, r, g1);
-    f->v[0] = secp256k1_i128_to_i64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
-    g->v[0] = secp256k1_i128_to_i64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
+    f->v[0] = secp256k1_i128_to_u64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
+    g->v[0] = secp256k1_i128_to_u64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
     /* Compute limb 2 of t*[f,g], and store it as output limb 1. */
     secp256k1_i128_accum_mul(&cf, u, f2);
     secp256k1_i128_accum_mul(&cf, v, g2);
     secp256k1_i128_accum_mul(&cg, q, f2);
     secp256k1_i128_accum_mul(&cg, r, g2);
-    f->v[1] = secp256k1_i128_to_i64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
-    g->v[1] = secp256k1_i128_to_i64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
+    f->v[1] = secp256k1_i128_to_u64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
+    g->v[1] = secp256k1_i128_to_u64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
     /* Compute limb 3 of t*[f,g], and store it as output limb 2. */
     secp256k1_i128_accum_mul(&cf, u, f3);
     secp256k1_i128_accum_mul(&cf, v, g3);
     secp256k1_i128_accum_mul(&cg, q, f3);
     secp256k1_i128_accum_mul(&cg, r, g3);
-    f->v[2] = secp256k1_i128_to_i64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
-    g->v[2] = secp256k1_i128_to_i64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
+    f->v[2] = secp256k1_i128_to_u64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
+    g->v[2] = secp256k1_i128_to_u64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
     /* Compute limb 4 of t*[f,g], and store it as output limb 3. */
     secp256k1_i128_accum_mul(&cf, u, f4);
     secp256k1_i128_accum_mul(&cf, v, g4);
     secp256k1_i128_accum_mul(&cg, q, f4);
     secp256k1_i128_accum_mul(&cg, r, g4);
-    f->v[3] = secp256k1_i128_to_i64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
-    g->v[3] = secp256k1_i128_to_i64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
+    f->v[3] = secp256k1_i128_to_u64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
+    g->v[3] = secp256k1_i128_to_u64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
     /* What remains is limb 5 of t*[f,g]; store it as output limb 4. */
     f->v[4] = secp256k1_i128_to_i64(&cf);
     g->v[4] = secp256k1_i128_to_i64(&cg);
@@ -460,7 +551,7 @@ static void secp256k1_modinv64_update_fg_62(secp256k1_modinv64_signed62 *f, secp
  * This implements the update_fg function from the explanation.
  */
 static void secp256k1_modinv64_update_fg_62_var(int len, secp256k1_modinv64_signed62 *f, secp256k1_modinv64_signed62 *g, const secp256k1_modinv64_trans2x2 *t) {
-    const int64_t M62 = (int64_t)(UINT64_MAX >> 2);
+    const uint64_t M62 = UINT64_MAX >> 2;
     const int64_t u = t->u, v = t->v, q = t->q, r = t->r;
     int64_t fi, gi;
     secp256k1_int128 cf, cg;
@@ -474,8 +565,8 @@ static void secp256k1_modinv64_update_fg_62_var(int len, secp256k1_modinv64_sign
     secp256k1_i128_mul(&cg, q, fi);
     secp256k1_i128_accum_mul(&cg, r, gi);
     /* Verify that the bottom 62 bits of the result are zero, and then throw them away. */
-    VERIFY_CHECK((secp256k1_i128_to_i64(&cf) & M62) == 0); secp256k1_i128_rshift(&cf, 62);
-    VERIFY_CHECK((secp256k1_i128_to_i64(&cg) & M62) == 0); secp256k1_i128_rshift(&cg, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&cf) & M62) == 0); secp256k1_i128_rshift(&cf, 62);
+    VERIFY_CHECK((secp256k1_i128_to_u64(&cg) & M62) == 0); secp256k1_i128_rshift(&cg, 62);
     /* Now iteratively compute limb i=1..len of t*[f,g], and store them in output limb i-1 (shifting
      * down by 62 bits). */
     for (i = 1; i < len; ++i) {
@@ -485,8 +576,8 @@ static void secp256k1_modinv64_update_fg_62_var(int len, secp256k1_modinv64_sign
         secp256k1_i128_accum_mul(&cf, v, gi);
         secp256k1_i128_accum_mul(&cg, q, fi);
         secp256k1_i128_accum_mul(&cg, r, gi);
-        f->v[i - 1] = secp256k1_i128_to_i64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
-        g->v[i - 1] = secp256k1_i128_to_i64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
+        f->v[i - 1] = secp256k1_i128_to_u64(&cf) & M62; secp256k1_i128_rshift(&cf, 62);
+        g->v[i - 1] = secp256k1_i128_to_u64(&cg) & M62; secp256k1_i128_rshift(&cg, 62);
     }
     /* What remains is limb (len) of t*[f,g]; store it as output limb (len-1). */
     f->v[len - 1] = secp256k1_i128_to_i64(&cf);
@@ -511,25 +602,23 @@ static void secp256k1_modinv64(secp256k1_modinv64_signed62 *x, const secp256k1_m
         /* Update d,e using that transition matrix. */
         secp256k1_modinv64_update_de_62(&d, &e, &t, modinfo);
         /* Update f,g using that transition matrix. */
-#ifdef VERIFY
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, 5, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, 5, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
+
         secp256k1_modinv64_update_fg_62(&f, &g, &t);
-#ifdef VERIFY
+
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, 5, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, 5, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
     }
 
     /* At this point sufficient iterations have been performed that g must have reached 0
      * and (if g was not originally 0) f must now equal +/- GCD of the initial f, g
      * values i.e. +/- 1, and d now contains +/- the modular inverse. */
-#ifdef VERIFY
+
     /* g == 0 */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, 5, &SECP256K1_SIGNED62_ONE, 0) == 0);
     /* |f| == 1, or (x == 0 and d == 0 and |f|=modulus) */
@@ -539,7 +628,6 @@ static void secp256k1_modinv64(secp256k1_modinv64_signed62 *x, const secp256k1_m
                   secp256k1_modinv64_mul_cmp_62(&d, 5, &SECP256K1_SIGNED62_ONE, 0) == 0 &&
                   (secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, 1) == 0 ||
                    secp256k1_modinv64_mul_cmp_62(&f, 5, &modinfo->modulus, -1) == 0)));
-#endif
 
     /* Optionally negate d, normalize to [0,modulus), and return it. */
     secp256k1_modinv64_normalize_62(&d, f.v[4], modinfo);
@@ -568,12 +656,11 @@ static void secp256k1_modinv64_var(secp256k1_modinv64_signed62 *x, const secp256
         /* Update d,e using that transition matrix. */
         secp256k1_modinv64_update_de_62(&d, &e, &t, modinfo);
         /* Update f,g using that transition matrix. */
-#ifdef VERIFY
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
+
         secp256k1_modinv64_update_fg_62_var(len, &f, &g, &t);
         /* If the bottom limb of g is zero, there is a chance that g=0. */
         if (g.v[0] == 0) {
@@ -598,18 +685,17 @@ static void secp256k1_modinv64_var(secp256k1_modinv64_signed62 *x, const secp256
             g.v[len - 2] |= (uint64_t)gn << 62;
             --len;
         }
-#ifdef VERIFY
+
         VERIFY_CHECK(++i < 12); /* We should never need more than 12*62 = 744 divsteps */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, -1) > 0); /* f > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, -1) > 0); /* g > -modulus */
         VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 1) < 0);  /* g <  modulus */
-#endif
     }
 
     /* At this point g is 0 and (if g was not originally 0) f must now equal +/- GCD of
      * the initial f, g values i.e. +/- 1, and d now contains +/- the modular inverse. */
-#ifdef VERIFY
+
     /* g == 0 */
     VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &SECP256K1_SIGNED62_ONE, 0) == 0);
     /* |f| == 1, or (x == 0 and d == 0 and |f|=modulus) */
@@ -619,11 +705,78 @@ static void secp256k1_modinv64_var(secp256k1_modinv64_signed62 *x, const secp256
                   secp256k1_modinv64_mul_cmp_62(&d, 5, &SECP256K1_SIGNED62_ONE, 0) == 0 &&
                   (secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 1) == 0 ||
                    secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, -1) == 0)));
-#endif
 
     /* Optionally negate d, normalize to [0,modulus), and return it. */
     secp256k1_modinv64_normalize_62(&d, f.v[len - 1], modinfo);
     *x = d;
 }
 
+/* Do up to 25 iterations of 62 posdivsteps (up to 1550 steps; more is extremely rare) each until f=1.
+ * In VERIFY mode use a lower number of iterations (744, close to the median 756), so failure actually occurs. */
+#ifdef VERIFY
+#define JACOBI64_ITERATIONS 12
+#else
+#define JACOBI64_ITERATIONS 25
+#endif
+
+/* Compute the Jacobi symbol of x modulo modinfo->modulus (variable time). gcd(x,modulus) must be 1. */
+static int secp256k1_jacobi64_maybe_var(const secp256k1_modinv64_signed62 *x, const secp256k1_modinv64_modinfo *modinfo) {
+    /* Start with f=modulus, g=x, eta=-1. */
+    secp256k1_modinv64_signed62 f = modinfo->modulus;
+    secp256k1_modinv64_signed62 g = *x;
+    int j, len = 5;
+    int64_t eta = -1; /* eta = -delta; delta is initially 1 */
+    int64_t cond, fn, gn;
+    int jac = 0;
+    int count;
+
+    /* The input limbs must all be non-negative. */
+    VERIFY_CHECK(g.v[0] >= 0 && g.v[1] >= 0 && g.v[2] >= 0 && g.v[3] >= 0 && g.v[4] >= 0);
+
+    /* If x > 0, then if the loop below converges, it converges to f=g=gcd(x,modulus). Since we
+     * require that gcd(x,modulus)=1 and modulus>=3, x cannot be 0. Thus, we must reach f=1 (or
+     * time out). */
+    VERIFY_CHECK((g.v[0] | g.v[1] | g.v[2] | g.v[3] | g.v[4]) != 0);
+
+    for (count = 0; count < JACOBI64_ITERATIONS; ++count) {
+        /* Compute transition matrix and new eta after 62 posdivsteps. */
+        secp256k1_modinv64_trans2x2 t;
+        eta = secp256k1_modinv64_posdivsteps_62_var(eta, f.v[0] | ((uint64_t)f.v[1] << 62), g.v[0] | ((uint64_t)g.v[1] << 62), &t, &jac);
+        /* Update f,g using that transition matrix. */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 0) > 0); /* f > 0 */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 0) > 0); /* g > 0 */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 1) < 0);  /* g < modulus */
+
+        secp256k1_modinv64_update_fg_62_var(len, &f, &g, &t);
+        /* If the bottom limb of f is 1, there is a chance that f=1. */
+        if (f.v[0] == 1) {
+            cond = 0;
+            /* Check if the other limbs are also 0. */
+            for (j = 1; j < len; ++j) {
+                cond |= f.v[j];
+            }
+            /* If so, we're done. When f=1, the Jacobi symbol (g | f)=1. */
+            if (cond == 0) return 1 - 2*(jac & 1);
+        }
+
+        /* Determine if len>1 and limb (len-1) of both f and g is 0. */
+        fn = f.v[len - 1];
+        gn = g.v[len - 1];
+        cond = ((int64_t)len - 2) >> 63;
+        cond |= fn;
+        cond |= gn;
+        /* If so, reduce length. */
+        if (cond == 0) --len;
+
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 0) > 0); /* f > 0 */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&f, len, &modinfo->modulus, 1) <= 0); /* f <= modulus */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 0) > 0); /* g > 0 */
+        VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(&g, len, &modinfo->modulus, 1) < 0);  /* g < modulus */
+    }
+
+    /* The loop failed to converge to f=g after 1550 iterations. Return 0, indicating unknown result. */
+    return 0;
+}
+
 #endif /* SECP256K1_MODINV64_IMPL_H */

src/modules/ecdh/bench_impl.h

@@ -42,7 +42,7 @@ static void bench_ecdh(void* arg, int iters) {
     }
 }
 
-void run_ecdh_bench(int iters, int argc, char** argv) {
+static void run_ecdh_bench(int iters, int argc, char** argv) {
     bench_ecdh_data data;
     int d = argc == 1;
 

src/modules/ecdh/main_impl.h

@@ -50,7 +50,7 @@ int secp256k1_ecdh(const secp256k1_context* ctx, unsigned char *output, const se
     overflow |= secp256k1_scalar_is_zero(&s);
     secp256k1_scalar_cmov(&s, &secp256k1_scalar_one, overflow);
 
-    secp256k1_ecmult_const(&res, &pt, &s, 256);
+    secp256k1_ecmult_const(&res, &pt, &s);
     secp256k1_ge_set_gej(&pt, &res);
 
     /* Compute a hash of the point */

src/modules/ecdh/tests_impl.h

@@ -7,7 +7,7 @@
 #ifndef SECP256K1_MODULE_ECDH_TESTS_H
 #define SECP256K1_MODULE_ECDH_TESTS_H
 
-int ecdh_hash_function_test_fail(unsigned char *output, const unsigned char *x, const unsigned char *y, void *data) {
+static int ecdh_hash_function_test_fail(unsigned char *output, const unsigned char *x, const unsigned char *y, void *data) {
     (void)output;
     (void)x;
     (void)y;
@@ -15,7 +15,7 @@ int ecdh_hash_function_test_fail(unsigned char *output, const unsigned char *x,
     return 0;
 }
 
-int ecdh_hash_function_custom(unsigned char *output, const unsigned char *x, const unsigned char *y, void *data) {
+static int ecdh_hash_function_custom(unsigned char *output, const unsigned char *x, const unsigned char *y, void *data) {
     (void)data;
     /* Save x and y as uncompressed public key */
     output[0] = 0x04;
@@ -24,43 +24,30 @@ int ecdh_hash_function_custom(unsigned char *output, const unsigned char *x, con
     return 1;
 }
 
-void test_ecdh_api(void) {
-    /* Setup context that just counts errors */
-    secp256k1_context *tctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+static void test_ecdh_api(void) {
     secp256k1_pubkey point;
     unsigned char res[32];
     unsigned char s_one[32] = { 0 };
-    int32_t ecount = 0;
     s_one[31] = 1;
 
-    secp256k1_context_set_error_callback(tctx, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_illegal_callback(tctx, counting_illegal_callback_fn, &ecount);
-    CHECK(secp256k1_ec_pubkey_create(tctx, &point, s_one) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &point, s_one) == 1);
 
     /* Check all NULLs are detected */
-    CHECK(secp256k1_ecdh(tctx, res, &point, s_one, NULL, NULL) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_ecdh(tctx, NULL, &point, s_one, NULL, NULL) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_ecdh(tctx, res, NULL, s_one, NULL, NULL) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_ecdh(tctx, res, &point, NULL, NULL, NULL) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_ecdh(tctx, res, &point, s_one, NULL, NULL) == 1);
-    CHECK(ecount == 3);
-
-    /* Cleanup */
-    secp256k1_context_destroy(tctx);
+    CHECK(secp256k1_ecdh(CTX, res, &point, s_one, NULL, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_ecdh(CTX, NULL, &point, s_one, NULL, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdh(CTX, res, NULL, s_one, NULL, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdh(CTX, res, &point, NULL, NULL, NULL));
+    CHECK(secp256k1_ecdh(CTX, res, &point, s_one, NULL, NULL) == 1);
 }
 
-void test_ecdh_generator_basepoint(void) {
+static void test_ecdh_generator_basepoint(void) {
     unsigned char s_one[32] = { 0 };
     secp256k1_pubkey point[2];
     int i;
 
     s_one[31] = 1;
     /* Check against pubkey creation when the basepoint is the generator */
-    for (i = 0; i < 2 * count; ++i) {
+    for (i = 0; i < 2 * COUNT; ++i) {
         secp256k1_sha256 sha;
         unsigned char s_b32[32];
         unsigned char output_ecdh[65];
@@ -72,20 +59,20 @@ void test_ecdh_generator_basepoint(void) {
         random_scalar_order(&s);
         secp256k1_scalar_get_b32(s_b32, &s);
 
-        CHECK(secp256k1_ec_pubkey_create(ctx, &point[0], s_one) == 1);
-        CHECK(secp256k1_ec_pubkey_create(ctx, &point[1], s_b32) == 1);
+        CHECK(secp256k1_ec_pubkey_create(CTX, &point[0], s_one) == 1);
+        CHECK(secp256k1_ec_pubkey_create(CTX, &point[1], s_b32) == 1);
 
         /* compute using ECDH function with custom hash function */
-        CHECK(secp256k1_ecdh(ctx, output_ecdh, &point[0], s_b32, ecdh_hash_function_custom, NULL) == 1);
+        CHECK(secp256k1_ecdh(CTX, output_ecdh, &point[0], s_b32, ecdh_hash_function_custom, NULL) == 1);
         /* compute "explicitly" */
-        CHECK(secp256k1_ec_pubkey_serialize(ctx, point_ser, &point_ser_len, &point[1], SECP256K1_EC_UNCOMPRESSED) == 1);
+        CHECK(secp256k1_ec_pubkey_serialize(CTX, point_ser, &point_ser_len, &point[1], SECP256K1_EC_UNCOMPRESSED) == 1);
         /* compare */
         CHECK(secp256k1_memcmp_var(output_ecdh, point_ser, 65) == 0);
 
         /* compute using ECDH function with default hash function */
-        CHECK(secp256k1_ecdh(ctx, output_ecdh, &point[0], s_b32, NULL, NULL) == 1);
+        CHECK(secp256k1_ecdh(CTX, output_ecdh, &point[0], s_b32, NULL, NULL) == 1);
         /* compute "explicitly" */
-        CHECK(secp256k1_ec_pubkey_serialize(ctx, point_ser, &point_ser_len, &point[1], SECP256K1_EC_COMPRESSED) == 1);
+        CHECK(secp256k1_ec_pubkey_serialize(CTX, point_ser, &point_ser_len, &point[1], SECP256K1_EC_COMPRESSED) == 1);
         secp256k1_sha256_initialize(&sha);
         secp256k1_sha256_write(&sha, point_ser, point_ser_len);
         secp256k1_sha256_finalize(&sha, output_ser);
@@ -94,7 +81,7 @@ void test_ecdh_generator_basepoint(void) {
     }
 }
 
-void test_bad_scalar(void) {
+static void test_bad_scalar(void) {
     unsigned char s_zero[32] = { 0 };
     unsigned char s_overflow[32] = {
         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
@@ -110,21 +97,21 @@ void test_bad_scalar(void) {
     /* Create random point */
     random_scalar_order(&rand);
     secp256k1_scalar_get_b32(s_rand, &rand);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &point, s_rand) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &point, s_rand) == 1);
 
     /* Try to multiply it by bad values */
-    CHECK(secp256k1_ecdh(ctx, output, &point, s_zero, NULL, NULL) == 0);
-    CHECK(secp256k1_ecdh(ctx, output, &point, s_overflow, NULL, NULL) == 0);
+    CHECK(secp256k1_ecdh(CTX, output, &point, s_zero, NULL, NULL) == 0);
+    CHECK(secp256k1_ecdh(CTX, output, &point, s_overflow, NULL, NULL) == 0);
     /* ...and a good one */
     s_overflow[31] -= 1;
-    CHECK(secp256k1_ecdh(ctx, output, &point, s_overflow, NULL, NULL) == 1);
+    CHECK(secp256k1_ecdh(CTX, output, &point, s_overflow, NULL, NULL) == 1);
 
     /* Hash function failure results in ecdh failure */
-    CHECK(secp256k1_ecdh(ctx, output, &point, s_overflow, ecdh_hash_function_test_fail, NULL) == 0);
+    CHECK(secp256k1_ecdh(CTX, output, &point, s_overflow, ecdh_hash_function_test_fail, NULL) == 0);
 }
 
 /** Test that ECDH(sG, 1/s) == ECDH((1/s)G, s) == ECDH(G, 1) for a few random s. */
-void test_result_basepoint(void) {
+static void test_result_basepoint(void) {
     secp256k1_pubkey point;
     secp256k1_scalar rand;
     unsigned char s[32];
@@ -136,26 +123,26 @@ void test_result_basepoint(void) {
 
     unsigned char s_one[32] = { 0 };
     s_one[31] = 1;
-    CHECK(secp256k1_ec_pubkey_create(ctx, &point, s_one) == 1);
-    CHECK(secp256k1_ecdh(ctx, out_base, &point, s_one, NULL, NULL) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &point, s_one) == 1);
+    CHECK(secp256k1_ecdh(CTX, out_base, &point, s_one, NULL, NULL) == 1);
 
-    for (i = 0; i < 2 * count; i++) {
+    for (i = 0; i < 2 * COUNT; i++) {
         random_scalar_order(&rand);
         secp256k1_scalar_get_b32(s, &rand);
         secp256k1_scalar_inverse(&rand, &rand);
         secp256k1_scalar_get_b32(s_inv, &rand);
 
-        CHECK(secp256k1_ec_pubkey_create(ctx, &point, s) == 1);
-        CHECK(secp256k1_ecdh(ctx, out, &point, s_inv, NULL, NULL) == 1);
+        CHECK(secp256k1_ec_pubkey_create(CTX, &point, s) == 1);
+        CHECK(secp256k1_ecdh(CTX, out, &point, s_inv, NULL, NULL) == 1);
         CHECK(secp256k1_memcmp_var(out, out_base, 32) == 0);
 
-        CHECK(secp256k1_ec_pubkey_create(ctx, &point, s_inv) == 1);
-        CHECK(secp256k1_ecdh(ctx, out_inv, &point, s, NULL, NULL) == 1);
+        CHECK(secp256k1_ec_pubkey_create(CTX, &point, s_inv) == 1);
+        CHECK(secp256k1_ecdh(CTX, out_inv, &point, s, NULL, NULL) == 1);
         CHECK(secp256k1_memcmp_var(out_inv, out_base, 32) == 0);
     }
 }
 
-void run_ecdh_tests(void) {
+static void run_ecdh_tests(void) {
     test_ecdh_api();
     test_ecdh_generator_basepoint();
     test_bad_scalar();

src/modules/ellswift/Makefile.am.include

@@ -0,0 +1,5 @@
+include_HEADERS += include/secp256k1_ellswift.h
+noinst_HEADERS += src/modules/ellswift/bench_impl.h
+noinst_HEADERS += src/modules/ellswift/main_impl.h
+noinst_HEADERS += src/modules/ellswift/tests_impl.h
+noinst_HEADERS += src/modules/ellswift/tests_exhaustive_impl.h

src/modules/ellswift/bench_impl.h

@@ -0,0 +1,106 @@
+/***********************************************************************
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_MODULE_ELLSWIFT_BENCH_H
+#define SECP256K1_MODULE_ELLSWIFT_BENCH_H
+
+#include "../../../include/secp256k1_ellswift.h"
+
+typedef struct {
+    secp256k1_context *ctx;
+    secp256k1_pubkey point[256];
+    unsigned char rnd64[64];
+} bench_ellswift_data;
+
+static void bench_ellswift_setup(void *arg) {
+    int i;
+    bench_ellswift_data *data = (bench_ellswift_data*)arg;
+    static const unsigned char init[64] = {
+        0x78, 0x1f, 0xb7, 0xd4, 0x67, 0x7f, 0x08, 0x68,
+        0xdb, 0xe3, 0x1d, 0x7f, 0x1b, 0xb0, 0xf6, 0x9e,
+        0x0a, 0x64, 0xca, 0x32, 0x9e, 0xc6, 0x20, 0x79,
+        0x03, 0xf3, 0xd0, 0x46, 0x7a, 0x0f, 0xd2, 0x21,
+        0xb0, 0x2c, 0x46, 0xd8, 0xba, 0xca, 0x26, 0x4f,
+        0x8f, 0x8c, 0xd4, 0xdd, 0x2d, 0x04, 0xbe, 0x30,
+        0x48, 0x51, 0x1e, 0xd4, 0x16, 0xfd, 0x42, 0x85,
+        0x62, 0xc9, 0x02, 0xf9, 0x89, 0x84, 0xff, 0xdc
+    };
+    memcpy(data->rnd64, init, 64);
+    for (i = 0; i < 256; ++i) {
+        int j;
+        CHECK(secp256k1_ellswift_decode(data->ctx, &data->point[i], data->rnd64));
+        for (j = 0; j < 64; ++j) {
+            data->rnd64[j] += 1;
+        }
+    }
+    CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[255], init + 16));
+}
+
+static void bench_ellswift_encode(void *arg, int iters) {
+    int i;
+    bench_ellswift_data *data = (bench_ellswift_data*)arg;
+
+    for (i = 0; i < iters; i++) {
+        CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[i & 255], data->rnd64 + 16));
+    }
+}
+
+static void bench_ellswift_create(void *arg, int iters) {
+    int i;
+    bench_ellswift_data *data = (bench_ellswift_data*)arg;
+
+    for (i = 0; i < iters; i++) {
+        unsigned char buf[64];
+        CHECK(secp256k1_ellswift_create(data->ctx, buf, data->rnd64, data->rnd64 + 32));
+        memcpy(data->rnd64, buf, 64);
+    }
+}
+
+static void bench_ellswift_decode(void *arg, int iters) {
+    int i;
+    secp256k1_pubkey out;
+    size_t len;
+    bench_ellswift_data *data = (bench_ellswift_data*)arg;
+
+    for (i = 0; i < iters; i++) {
+        CHECK(secp256k1_ellswift_decode(data->ctx, &out, data->rnd64) == 1);
+        len = 33;
+        CHECK(secp256k1_ec_pubkey_serialize(data->ctx, data->rnd64 + (i % 32), &len, &out, SECP256K1_EC_COMPRESSED));
+    }
+}
+
+static void bench_ellswift_xdh(void *arg, int iters) {
+    int i;
+    bench_ellswift_data *data = (bench_ellswift_data*)arg;
+
+    for (i = 0; i < iters; i++) {
+        int party = i & 1;
+        CHECK(secp256k1_ellswift_xdh(data->ctx,
+                                     data->rnd64 + (i % 33),
+                                     data->rnd64,
+                                     data->rnd64,
+                                     data->rnd64 + ((i + 16) % 33),
+                                     party,
+                                     secp256k1_ellswift_xdh_hash_function_bip324,
+                                     NULL) == 1);
+    }
+}
+
+void run_ellswift_bench(int iters, int argc, char **argv) {
+    bench_ellswift_data data;
+    int d = argc == 1;
+
+    /* create a context with signing capabilities */
+    data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+
+    if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "encode") || have_flag(argc, argv, "ellswift_encode")) run_benchmark("ellswift_encode", bench_ellswift_encode, bench_ellswift_setup, NULL, &data, 10, iters);
+    if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "decode") || have_flag(argc, argv, "ellswift_decode")) run_benchmark("ellswift_decode", bench_ellswift_decode, bench_ellswift_setup, NULL, &data, 10, iters);
+    if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ellswift_keygen")) run_benchmark("ellswift_keygen", bench_ellswift_create, bench_ellswift_setup, NULL, &data, 10, iters);
+    if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "ecdh") || have_flag(argc, argv, "ellswift_ecdh")) run_benchmark("ellswift_ecdh", bench_ellswift_xdh, bench_ellswift_setup, NULL, &data, 10, iters);
+
+    secp256k1_context_destroy(data.ctx);
+}
+
+#endif

src/modules/ellswift/main_impl.h

@@ -0,0 +1,590 @@
+/***********************************************************************
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_MODULE_ELLSWIFT_MAIN_H
+#define SECP256K1_MODULE_ELLSWIFT_MAIN_H
+
+#include "../../../include/secp256k1.h"
+#include "../../../include/secp256k1_ellswift.h"
+#include "../../eckey.h"
+#include "../../hash.h"
+
+/** c1 = (sqrt(-3)-1)/2 */
+static const secp256k1_fe secp256k1_ellswift_c1 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa40);
+/** c2 = (-sqrt(-3)-1)/2 = -(c1+1) */
+static const secp256k1_fe secp256k1_ellswift_c2 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ee);
+/** c3 = (-sqrt(-3)+1)/2 = -c1 = c2+1 */
+static const secp256k1_fe secp256k1_ellswift_c3 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ef);
+/** c4 = (sqrt(-3)+1)/2 = -c2 = c1+1 */
+static const secp256k1_fe secp256k1_ellswift_c4 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa41);
+
+/** Decode ElligatorSwift encoding (u, t) to a fraction xn/xd representing a curve X coordinate. */
+static void secp256k1_ellswift_xswiftec_frac_var(secp256k1_fe *xn, secp256k1_fe *xd, const secp256k1_fe *u, const secp256k1_fe *t) {
+    /* The implemented algorithm is the following (all operations in GF(p)):
+     *
+     * - Let c0 = sqrt(-3) = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852.
+     * - If u = 0, set u = 1.
+     * - If t = 0, set t = 1.
+     * - If u^3+7+t^2 = 0, set t = 2*t.
+     * - Let X = (u^3+7-t^2)/(2*t).
+     * - Let Y = (X+t)/(c0*u).
+     * - If x3 = u+4*Y^2 is a valid x coordinate, return it.
+     * - If x2 = (-X/Y-u)/2 is a valid x coordinate, return it.
+     * - Return x1 = (X/Y-u)/2 (which is now guaranteed to be a valid x coordinate).
+     *
+     * Introducing s=t^2, g=u^3+7, and simplifying x1=-(x2+u) we get:
+     *
+     * - Let c0 = ...
+     * - If u = 0, set u = 1.
+     * - If t = 0, set t = 1.
+     * - Let s = t^2
+     * - Let g = u^3+7
+     * - If g+s = 0, set t = 2*t, s = 4*s
+     * - Let X = (g-s)/(2*t).
+     * - Let Y = (X+t)/(c0*u) = (g+s)/(2*c0*t*u).
+     * - If x3 = u+4*Y^2 is a valid x coordinate, return it.
+     * - If x2 = (-X/Y-u)/2 is a valid x coordinate, return it.
+     * - Return x1 = -(x2+u).
+     *
+     * Now substitute Y^2 = -(g+s)^2/(12*s*u^2) and X/Y = c0*u*(g-s)/(g+s). This
+     * means X and Y do not need to be evaluated explicitly anymore.
+     *
+     * - ...
+     * - If g+s = 0, set s = 4*s.
+     * - If x3 = u-(g+s)^2/(3*s*u^2) is a valid x coordinate, return it.
+     * - If x2 = (-c0*u*(g-s)/(g+s)-u)/2 is a valid x coordinate, return it.
+     * - Return x1 = -(x2+u).
+     *
+     * Simplifying x2 using 2 additional constants:
+     *
+     * - Let c1 = (c0-1)/2 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40.
+     * - Let c2 = (-c0-1)/2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee.
+     * - ...
+     * - If x2 = u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it.
+     * - ...
+     *
+     * Writing x3 as a fraction:
+     *
+     * - ...
+     * - If x3 = (3*s*u^3-(g+s)^2)/(3*s*u^2) ...
+     * - ...
+
+     * Overall, we get:
+     *
+     * - Let c1 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40.
+     * - Let c2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee.
+     * - If u = 0, set u = 1.
+     * - If t = 0, set s = 1, else set s = t^2.
+     * - Let g = u^3+7.
+     * - If g+s = 0, set s = 4*s.
+     * - If x3 = (3*s*u^3-(g+s)^2)/(3*s*u^2) is a valid x coordinate, return it.
+     * - If x2 = u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it.
+     * - Return x1 = -(x2+u).
+     */
+    secp256k1_fe u1, s, g, p, d, n, l;
+    u1 = *u;
+    if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&u1), 0)) u1 = secp256k1_fe_one;
+    secp256k1_fe_sqr(&s, t);
+    if (EXPECT(secp256k1_fe_normalizes_to_zero_var(t), 0)) s = secp256k1_fe_one;
+    secp256k1_fe_sqr(&l, &u1);                                   /* l = u^2 */
+    secp256k1_fe_mul(&g, &l, &u1);                               /* g = u^3 */
+    secp256k1_fe_add_int(&g, SECP256K1_B);                       /* g = u^3 + 7 */
+    p = g;                                                       /* p = g */
+    secp256k1_fe_add(&p, &s);                                    /* p = g+s */
+    if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&p), 0)) {
+        secp256k1_fe_mul_int(&s, 4);
+        /* Recompute p = g+s */
+        p = g;                                                   /* p = g */
+        secp256k1_fe_add(&p, &s);                                /* p = g+s */
+    }
+    secp256k1_fe_mul(&d, &s, &l);                                /* d = s*u^2 */
+    secp256k1_fe_mul_int(&d, 3);                                 /* d = 3*s*u^2 */
+    secp256k1_fe_sqr(&l, &p);                                    /* l = (g+s)^2 */
+    secp256k1_fe_negate(&l, &l, 1);                              /* l = -(g+s)^2 */
+    secp256k1_fe_mul(&n, &d, &u1);                               /* n = 3*s*u^3 */
+    secp256k1_fe_add(&n, &l);                                    /* n = 3*s*u^3-(g+s)^2 */
+    if (secp256k1_ge_x_frac_on_curve_var(&n, &d)) {
+        /* Return x3 = n/d = (3*s*u^3-(g+s)^2)/(3*s*u^2) */
+        *xn = n;
+        *xd = d;
+        return;
+    }
+    *xd = p;
+    secp256k1_fe_mul(&l, &secp256k1_ellswift_c1, &s);            /* l = c1*s */
+    secp256k1_fe_mul(&n, &secp256k1_ellswift_c2, &g);            /* n = c2*g */
+    secp256k1_fe_add(&n, &l);                                    /* n = c1*s+c2*g */
+    secp256k1_fe_mul(&n, &n, &u1);                               /* n = u*(c1*s+c2*g) */
+    /* Possible optimization: in the invocation below, p^2 = (g+s)^2 is computed,
+     * which we already have computed above. This could be deduplicated. */
+    if (secp256k1_ge_x_frac_on_curve_var(&n, &p)) {
+        /* Return x2 = n/p = u*(c1*s+c2*g)/(g+s) */
+        *xn = n;
+        return;
+    }
+    secp256k1_fe_mul(&l, &p, &u1);                               /* l = u*(g+s) */
+    secp256k1_fe_add(&n, &l);                                    /* n = u*(c1*s+c2*g)+u*(g+s) */
+    secp256k1_fe_negate(xn, &n, 2);                              /* n = -u*(c1*s+c2*g)-u*(g+s) */
+
+    VERIFY_CHECK(secp256k1_ge_x_frac_on_curve_var(xn, &p));
+    /* Return x3 = n/p = -(u*(c1*s+c2*g)/(g+s)+u) */
+}
+
+/** Decode ElligatorSwift encoding (u, t) to X coordinate. */
+static void secp256k1_ellswift_xswiftec_var(secp256k1_fe *x, const secp256k1_fe *u, const secp256k1_fe *t) {
+    secp256k1_fe xn, xd;
+    secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, u, t);
+    secp256k1_fe_inv_var(&xd, &xd);
+    secp256k1_fe_mul(x, &xn, &xd);
+}
+
+/** Decode ElligatorSwift encoding (u, t) to point P. */
+static void secp256k1_ellswift_swiftec_var(secp256k1_ge *p, const secp256k1_fe *u, const secp256k1_fe *t) {
+    secp256k1_fe x;
+    secp256k1_ellswift_xswiftec_var(&x, u, t);
+    secp256k1_ge_set_xo_var(p, &x, secp256k1_fe_is_odd(t));
+}
+
+/* Try to complete an ElligatorSwift encoding (u, t) for X coordinate x, given u and x.
+ *
+ * There may be up to 8 distinct t values such that (u, t) decodes back to x, but also
+ * fewer, or none at all. Each such partial inverse can be accessed individually using a
+ * distinct input argument c (in range 0-7), and some or all of these may return failure.
+ * The following guarantees exist:
+ * - Given (x, u), no two distinct c values give the same successful result t.
+ * - Every successful result maps back to x through secp256k1_ellswift_xswiftec_var.
+ * - Given (x, u), all t values that map back to x can be reached by combining the
+ *   successful results from this function over all c values, with the exception of:
+ *   - this function cannot be called with u=0
+ *   - no result with t=0 will be returned
+ *   - no result for which u^3 + t^2 + 7 = 0 will be returned.
+ *
+ * The rather unusual encoding of bits in c (a large "if" based on the middle bit, and then
+ * using the low and high bits to pick signs of square roots) is to match the paper's
+ * encoding more closely: c=0 through c=3 match branches 1..4 in the paper, while c=4 through
+ * c=7 are copies of those with an additional negation of sqrt(w).
+ */
+static int secp256k1_ellswift_xswiftec_inv_var(secp256k1_fe *t, const secp256k1_fe *x_in, const secp256k1_fe *u_in, int c) {
+    /* The implemented algorithm is this (all arithmetic, except involving c, is mod p):
+     *
+     * - If (c & 2) = 0:
+     *   - If (-x-u) is a valid X coordinate, fail.
+     *   - Let s=-(u^3+7)/(u^2+u*x+x^2).
+     *   - If s is not square, fail.
+     *   - Let v=x.
+     * - If (c & 2) = 2:
+     *   - Let s=x-u.
+     *   - If s is not square, fail.
+     *   - Let r=sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist.
+     *   - If (c & 1) = 1 and r = 0, fail.
+     *   - If s=0, fail.
+     *   - Let v=(r/s-u)/2.
+     * - Let w=sqrt(s).
+     * - If (c & 5) = 0: return -w*(c3*u + v).
+     * - If (c & 5) = 1: return  w*(c4*u + v).
+     * - If (c & 5) = 4: return  w*(c3*u + v).
+     * - If (c & 5) = 5: return -w*(c4*u + v).
+     */
+    secp256k1_fe x = *x_in, u = *u_in, g, v, s, m, r, q;
+    int ret;
+
+    secp256k1_fe_normalize_weak(&x);
+    secp256k1_fe_normalize_weak(&u);
+
+    VERIFY_CHECK(c >= 0 && c < 8);
+    VERIFY_CHECK(secp256k1_ge_x_on_curve_var(&x));
+
+    if (!(c & 2)) {
+        /* c is in {0, 1, 4, 5}. In this case we look for an inverse under the x1 (if c=0 or
+         * c=4) formula, or x2 (if c=1 or c=5) formula. */
+
+        /* If -u-x is a valid X coordinate, fail. This would yield an encoding that roundtrips
+         * back under the x3 formula instead (which has priority over x1 and x2, so the decoding
+         * would not match x). */
+        m = x;                                          /* m = x */
+        secp256k1_fe_add(&m, &u);                       /* m = u+x */
+        secp256k1_fe_negate(&m, &m, 2);                 /* m = -u-x */
+        /* Test if (-u-x) is a valid X coordinate. If so, fail. */
+        if (secp256k1_ge_x_on_curve_var(&m)) return 0;
+
+        /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [first part] */
+        secp256k1_fe_sqr(&s, &m);                       /* s = (u+x)^2 */
+        secp256k1_fe_negate(&s, &s, 1);                 /* s = -(u+x)^2 */
+        secp256k1_fe_mul(&m, &u, &x);                   /* m = u*x */
+        secp256k1_fe_add(&s, &m);                       /* s = -(u^2 + u*x + x^2) */
+
+        /* Note that at this point, s = 0 is impossible. If it were the case:
+         *             s = -(u^2 + u*x + x^2) = 0
+         * =>                 u^2 + u*x + x^2 = 0
+         * =>   (u + 2*x) * (u^2 + u*x + x^2) = 0
+         * => 2*x^3 + 3*x^2*u + 3*x*u^2 + u^3 = 0
+         * =>                 (x + u)^3 + x^3 = 0
+         * =>                             x^3 = -(x + u)^3
+         * =>                         x^3 + B = (-u - x)^3 + B
+         *
+         * However, we know x^3 + B is square (because x is on the curve) and
+         * that (-u-x)^3 + B is not square (the secp256k1_ge_x_on_curve_var(&m)
+         * test above would have failed). This is a contradiction, and thus the
+         * assumption s=0 is false. */
+        VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(&s));
+
+        /* If s is not square, fail. We have not fully computed s yet, but s is square iff
+         * -(u^3+7)*(u^2+u*x+x^2) is square (because a/b is square iff a*b is square and b is
+         * nonzero). */
+        secp256k1_fe_sqr(&g, &u);                       /* g = u^2 */
+        secp256k1_fe_mul(&g, &g, &u);                   /* g = u^3 */
+        secp256k1_fe_add_int(&g, SECP256K1_B);          /* g = u^3+7 */
+        secp256k1_fe_mul(&m, &s, &g);                   /* m = -(u^3 + 7)*(u^2 + u*x + x^2) */
+        if (!secp256k1_fe_is_square_var(&m)) return 0;
+
+        /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [second part] */
+        secp256k1_fe_inv_var(&s, &s);                   /* s = -1/(u^2 + u*x + x^2) [no div by 0] */
+        secp256k1_fe_mul(&s, &s, &g);                   /* s = -(u^3 + 7)/(u^2 + u*x + x^2) */
+
+        /* Let v = x. */
+        v = x;
+    } else {
+        /* c is in {2, 3, 6, 7}. In this case we look for an inverse under the x3 formula. */
+
+        /* Let s = x-u. */
+        secp256k1_fe_negate(&m, &u, 1);                 /* m = -u */
+        s = m;                                          /* s = -u */
+        secp256k1_fe_add(&s, &x);                       /* s = x-u */
+
+        /* If s is not square, fail. */
+        if (!secp256k1_fe_is_square_var(&s)) return 0;
+
+        /* Let r = sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist. */
+        secp256k1_fe_sqr(&g, &u);                       /* g = u^2 */
+        secp256k1_fe_mul(&q, &s, &g);                   /* q = s*u^2 */
+        secp256k1_fe_mul_int(&q, 3);                    /* q = 3*s*u^2 */
+        secp256k1_fe_mul(&g, &g, &u);                   /* g = u^3 */
+        secp256k1_fe_mul_int(&g, 4);                    /* g = 4*u^3 */
+        secp256k1_fe_add_int(&g, 4 * SECP256K1_B);      /* g = 4*(u^3+7) */
+        secp256k1_fe_add(&q, &g);                       /* q = 4*(u^3+7)+3*s*u^2 */
+        secp256k1_fe_mul(&q, &q, &s);                   /* q = s*(4*(u^3+7)+3*u^2*s) */
+        secp256k1_fe_negate(&q, &q, 1);                 /* q = -s*(4*(u^3+7)+3*u^2*s) */
+        if (!secp256k1_fe_is_square_var(&q)) return 0;
+        ret = secp256k1_fe_sqrt(&r, &q);                /* r = sqrt(-s*(4*(u^3+7)+3*u^2*s)) */
+#ifdef VERIFY
+        VERIFY_CHECK(ret);
+#else
+        (void)ret;
+#endif
+
+        /* If (c & 1) = 1 and r = 0, fail. */
+        if (EXPECT((c & 1) && secp256k1_fe_normalizes_to_zero_var(&r), 0)) return 0;
+
+        /* If s = 0, fail. */
+        if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&s), 0)) return 0;
+
+        /* Let v = (r/s-u)/2. */
+        secp256k1_fe_inv_var(&v, &s);                   /* v = 1/s [no div by 0] */
+        secp256k1_fe_mul(&v, &v, &r);                   /* v = r/s */
+        secp256k1_fe_add(&v, &m);                       /* v = r/s-u */
+        secp256k1_fe_half(&v);                          /* v = (r/s-u)/2 */
+    }
+
+    /* Let w = sqrt(s). */
+    ret = secp256k1_fe_sqrt(&m, &s);                    /* m = sqrt(s) = w */
+    VERIFY_CHECK(ret);
+
+    /* Return logic. */
+    if ((c & 5) == 0 || (c & 5) == 5) {
+        secp256k1_fe_negate(&m, &m, 1);                 /* m = -w */
+    }
+    /* Now m = {-w if c&5=0 or c&5=5; w otherwise}. */
+    secp256k1_fe_mul(&u, &u, c&1 ? &secp256k1_ellswift_c4 : &secp256k1_ellswift_c3);
+    /* u = {c4 if c&1=1; c3 otherwise}*u */
+    secp256k1_fe_add(&u, &v);                           /* u = {c4 if c&1=1; c3 otherwise}*u + v */
+    secp256k1_fe_mul(t, &m, &u);
+    return 1;
+}
+
+/** Use SHA256 as a PRNG, returning SHA256(hasher || cnt).
+ *
+ * hasher is a SHA256 object to which an incrementing 4-byte counter is written to generate randomness.
+ * Writing 13 bytes (4 bytes for counter, plus 9 bytes for the SHA256 padding) cannot cross a
+ * 64-byte block size boundary (to make sure it only triggers a single SHA256 compression). */
+static void secp256k1_ellswift_prng(unsigned char* out32, const secp256k1_sha256 *hasher, uint32_t cnt) {
+    secp256k1_sha256 hash = *hasher;
+    unsigned char buf4[4];
+#ifdef VERIFY
+    size_t blocks = hash.bytes >> 6;
+#endif
+    buf4[0] = cnt;
+    buf4[1] = cnt >> 8;
+    buf4[2] = cnt >> 16;
+    buf4[3] = cnt >> 24;
+    secp256k1_sha256_write(&hash, buf4, 4);
+    secp256k1_sha256_finalize(&hash, out32);
+
+    /* Writing and finalizing together should trigger exactly one SHA256 compression. */
+    VERIFY_CHECK(((hash.bytes) >> 6) == (blocks + 1));
+}
+
+/** Find an ElligatorSwift encoding (u, t) for X coordinate x, and random Y coordinate.
+ *
+ * u32 is the 32-byte big endian encoding of u; t is the output field element t that still
+ * needs encoding.
+ *
+ * hasher is a hasher in the secp256k1_ellswift_prng sense, with the same restrictions. */
+static void secp256k1_ellswift_xelligatorswift_var(unsigned char *u32, secp256k1_fe *t, const secp256k1_fe *x, const secp256k1_sha256 *hasher) {
+    /* Pool of 3-bit branch values. */
+    unsigned char branch_hash[32];
+    /* Number of 3-bit values in branch_hash left. */
+    int branches_left = 0;
+    /* Field elements u and branch values are extracted from RNG based on hasher for consecutive
+     * values of cnt. cnt==0 is first used to populate a pool of 64 4-bit branch values. The 64
+     * cnt values that follow are used to generate field elements u. cnt==65 (and multiples
+     * thereof) are used to repopulate the pool and start over, if that were ever necessary.
+     * On average, 4 iterations are needed. */
+    uint32_t cnt = 0;
+    while (1) {
+        int branch;
+        secp256k1_fe u;
+        /* If the pool of branch values is empty, populate it. */
+        if (branches_left == 0) {
+            secp256k1_ellswift_prng(branch_hash, hasher, cnt++);
+            branches_left = 64;
+        }
+        /* Take a 3-bit branch value from the branch pool (top bit is discarded). */
+        --branches_left;
+        branch = (branch_hash[branches_left >> 1] >> ((branches_left & 1) << 2)) & 7;
+        /* Compute a new u value by hashing. */
+        secp256k1_ellswift_prng(u32, hasher, cnt++);
+        /* overflow is not a problem (we prefer uniform u32 over uniform u). */
+        secp256k1_fe_set_b32_mod(&u, u32);
+        /* Since u is the output of a hash, it should practically never be 0. We could apply the
+         * u=0 to u=1 correction here too to deal with that case still, but it's such a low
+         * probability event that we do not bother. */
+        VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(&u));
+
+        /* Find a remainder t, and return it if found. */
+        if (EXPECT(secp256k1_ellswift_xswiftec_inv_var(t, x, &u, branch), 0)) break;
+    }
+}
+
+/** Find an ElligatorSwift encoding (u, t) for point P.
+ *
+ * This is similar secp256k1_ellswift_xelligatorswift_var, except it takes a full group element p
+ * as input, and returns an encoding that matches the provided Y coordinate rather than a random
+ * one.
+ */
+static void secp256k1_ellswift_elligatorswift_var(unsigned char *u32, secp256k1_fe *t, const secp256k1_ge *p, const secp256k1_sha256 *hasher) {
+    secp256k1_ellswift_xelligatorswift_var(u32, t, &p->x, hasher);
+    secp256k1_fe_normalize_var(t);
+    if (secp256k1_fe_is_odd(t) != secp256k1_fe_is_odd(&p->y)) {
+        secp256k1_fe_negate(t, t, 1);
+        secp256k1_fe_normalize_var(t);
+    }
+}
+
+/** Set hash state to the BIP340 tagged hash midstate for "secp256k1_ellswift_encode". */
+static void secp256k1_ellswift_sha256_init_encode(secp256k1_sha256* hash) {
+    secp256k1_sha256_initialize(hash);
+    hash->s[0] = 0xd1a6524bul;
+    hash->s[1] = 0x028594b3ul;
+    hash->s[2] = 0x96e42f4eul;
+    hash->s[3] = 0x1037a177ul;
+    hash->s[4] = 0x1b8fcb8bul;
+    hash->s[5] = 0x56023885ul;
+    hash->s[6] = 0x2560ede1ul;
+    hash->s[7] = 0xd626b715ul;
+
+    hash->bytes = 64;
+}
+
+int secp256k1_ellswift_encode(const secp256k1_context *ctx, unsigned char *ell64, const secp256k1_pubkey *pubkey, const unsigned char *rnd32) {
+    secp256k1_ge p;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(ell64 != NULL);
+    ARG_CHECK(pubkey != NULL);
+    ARG_CHECK(rnd32 != NULL);
+
+    if (secp256k1_pubkey_load(ctx, &p, pubkey)) {
+        secp256k1_fe t;
+        unsigned char p64[64] = {0};
+        size_t ser_size;
+        int ser_ret;
+        secp256k1_sha256 hash;
+
+        /* Set up hasher state; the used RNG is H(pubkey || "\x00"*31 || rnd32 || cnt++), using
+         * BIP340 tagged hash with tag "secp256k1_ellswift_encode". */
+        secp256k1_ellswift_sha256_init_encode(&hash);
+        ser_ret = secp256k1_eckey_pubkey_serialize(&p, p64, &ser_size, 1);
+#ifdef VERIFY
+        VERIFY_CHECK(ser_ret && ser_size == 33);
+#else
+        (void)ser_ret;
+#endif
+        secp256k1_sha256_write(&hash, p64, sizeof(p64));
+        secp256k1_sha256_write(&hash, rnd32, 32);
+
+        /* Compute ElligatorSwift encoding and construct output. */
+        secp256k1_ellswift_elligatorswift_var(ell64, &t, &p, &hash); /* puts u in ell64[0..32] */
+        secp256k1_fe_get_b32(ell64 + 32, &t); /* puts t in ell64[32..64] */
+        return 1;
+    }
+    /* Only reached in case the provided pubkey is invalid. */
+    memset(ell64, 0, 64);
+    return 0;
+}
+
+/** Set hash state to the BIP340 tagged hash midstate for "secp256k1_ellswift_create". */
+static void secp256k1_ellswift_sha256_init_create(secp256k1_sha256* hash) {
+    secp256k1_sha256_initialize(hash);
+    hash->s[0] = 0xd29e1bf5ul;
+    hash->s[1] = 0xf7025f42ul;
+    hash->s[2] = 0x9b024773ul;
+    hash->s[3] = 0x094cb7d5ul;
+    hash->s[4] = 0xe59ed789ul;
+    hash->s[5] = 0x03bc9786ul;
+    hash->s[6] = 0x68335b35ul;
+    hash->s[7] = 0x4e363b53ul;
+
+    hash->bytes = 64;
+}
+
+int secp256k1_ellswift_create(const secp256k1_context *ctx, unsigned char *ell64, const unsigned char *seckey32, const unsigned char *auxrnd32) {
+    secp256k1_ge p;
+    secp256k1_fe t;
+    secp256k1_sha256 hash;
+    secp256k1_scalar seckey_scalar;
+    int ret;
+    static const unsigned char zero32[32] = {0};
+
+    /* Sanity check inputs. */
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(ell64 != NULL);
+    memset(ell64, 0, 64);
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(seckey32 != NULL);
+
+    /* Compute (affine) public key */
+    ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey32);
+    secp256k1_declassify(ctx, &p, sizeof(p)); /* not constant time in produced pubkey */
+    secp256k1_fe_normalize_var(&p.x);
+    secp256k1_fe_normalize_var(&p.y);
+
+    /* Set up hasher state. The used RNG is H(privkey || "\x00"*32 [|| auxrnd32] || cnt++),
+     * using BIP340 tagged hash with tag "secp256k1_ellswift_create". */
+    secp256k1_ellswift_sha256_init_create(&hash);
+    secp256k1_sha256_write(&hash, seckey32, 32);
+    secp256k1_sha256_write(&hash, zero32, sizeof(zero32));
+    secp256k1_declassify(ctx, &hash, sizeof(hash)); /* private key is hashed now */
+    if (auxrnd32) secp256k1_sha256_write(&hash, auxrnd32, 32);
+
+    /* Compute ElligatorSwift encoding and construct output. */
+    secp256k1_ellswift_elligatorswift_var(ell64, &t, &p, &hash); /* puts u in ell64[0..32] */
+    secp256k1_fe_get_b32(ell64 + 32, &t); /* puts t in ell64[32..64] */
+
+    secp256k1_memczero(ell64, 64, !ret);
+    secp256k1_scalar_clear(&seckey_scalar);
+
+    return ret;
+}
+
+int secp256k1_ellswift_decode(const secp256k1_context *ctx, secp256k1_pubkey *pubkey, const unsigned char *ell64) {
+    secp256k1_fe u, t;
+    secp256k1_ge p;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    ARG_CHECK(ell64 != NULL);
+
+    secp256k1_fe_set_b32_mod(&u, ell64);
+    secp256k1_fe_set_b32_mod(&t, ell64 + 32);
+    secp256k1_fe_normalize_var(&t);
+    secp256k1_ellswift_swiftec_var(&p, &u, &t);
+    secp256k1_pubkey_save(pubkey, &p);
+    return 1;
+}
+
+static int ellswift_xdh_hash_function_prefix(unsigned char *output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) {
+    secp256k1_sha256 sha;
+
+    secp256k1_sha256_initialize(&sha);
+    secp256k1_sha256_write(&sha, data, 64);
+    secp256k1_sha256_write(&sha, ell_a64, 64);
+    secp256k1_sha256_write(&sha, ell_b64, 64);
+    secp256k1_sha256_write(&sha, x32, 32);
+    secp256k1_sha256_finalize(&sha, output);
+
+    return 1;
+}
+
+/** Set hash state to the BIP340 tagged hash midstate for "bip324_ellswift_xonly_ecdh". */
+static void secp256k1_ellswift_sha256_init_bip324(secp256k1_sha256* hash) {
+    secp256k1_sha256_initialize(hash);
+    hash->s[0] = 0x8c12d730ul;
+    hash->s[1] = 0x827bd392ul;
+    hash->s[2] = 0x9e4fb2eeul;
+    hash->s[3] = 0x207b373eul;
+    hash->s[4] = 0x2292bd7aul;
+    hash->s[5] = 0xaa5441bcul;
+    hash->s[6] = 0x15c3779ful;
+    hash->s[7] = 0xcfb52549ul;
+
+    hash->bytes = 64;
+}
+
+static int ellswift_xdh_hash_function_bip324(unsigned char* output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) {
+    secp256k1_sha256 sha;
+
+    (void)data;
+
+    secp256k1_ellswift_sha256_init_bip324(&sha);
+    secp256k1_sha256_write(&sha, ell_a64, 64);
+    secp256k1_sha256_write(&sha, ell_b64, 64);
+    secp256k1_sha256_write(&sha, x32, 32);
+    secp256k1_sha256_finalize(&sha, output);
+
+    return 1;
+}
+
+const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_prefix = ellswift_xdh_hash_function_prefix;
+const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_bip324 = ellswift_xdh_hash_function_bip324;
+
+int secp256k1_ellswift_xdh(const secp256k1_context *ctx, unsigned char *output, const unsigned char *ell_a64, const unsigned char *ell_b64, const unsigned char *seckey32, int party, secp256k1_ellswift_xdh_hash_function hashfp, void *data) {
+    int ret = 0;
+    int overflow;
+    secp256k1_scalar s;
+    secp256k1_fe xn, xd, px, u, t;
+    unsigned char sx[32];
+    const unsigned char* theirs64;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(output != NULL);
+    ARG_CHECK(ell_a64 != NULL);
+    ARG_CHECK(ell_b64 != NULL);
+    ARG_CHECK(seckey32 != NULL);
+    ARG_CHECK(hashfp != NULL);
+
+    /* Load remote public key (as fraction). */
+    theirs64 = party ? ell_a64 : ell_b64;
+    secp256k1_fe_set_b32_mod(&u, theirs64);
+    secp256k1_fe_set_b32_mod(&t, theirs64 + 32);
+    secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, &u, &t);
+
+    /* Load private key (using one if invalid). */
+    secp256k1_scalar_set_b32(&s, seckey32, &overflow);
+    overflow = secp256k1_scalar_is_zero(&s);
+    secp256k1_scalar_cmov(&s, &secp256k1_scalar_one, overflow);
+
+    /* Compute shared X coordinate. */
+    secp256k1_ecmult_const_xonly(&px, &xn, &xd, &s, 1);
+    secp256k1_fe_normalize(&px);
+    secp256k1_fe_get_b32(sx, &px);
+
+    /* Invoke hasher */
+    ret = hashfp(output, sx, ell_a64, ell_b64, data);
+
+    memset(sx, 0, 32);
+    secp256k1_fe_clear(&px);
+    secp256k1_scalar_clear(&s);
+
+    return !!ret & !overflow;
+}
+
+#endif

src/modules/ellswift/tests_exhaustive_impl.h

@@ -0,0 +1,39 @@
+/***********************************************************************
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_MODULE_ELLSWIFT_TESTS_EXHAUSTIVE_H
+#define SECP256K1_MODULE_ELLSWIFT_TESTS_EXHAUSTIVE_H
+
+#include "../../../include/secp256k1_ellswift.h"
+#include "main_impl.h"
+
+static void test_exhaustive_ellswift(const secp256k1_context *ctx, const secp256k1_ge *group) {
+    int i;
+
+    /* Note that SwiftEC/ElligatorSwift are inherently curve operations, not
+     * group operations, and this test only checks the curve points which are in
+     * a tiny subgroup. In that sense it can't be really seen as exhaustive as
+     * it doesn't (and for computational reasons obviously cannot) test the
+     * entire domain ellswift operates under. */
+    for (i = 1; i < EXHAUSTIVE_TEST_ORDER; i++) {
+        secp256k1_scalar scalar_i;
+        unsigned char sec32[32];
+        unsigned char ell64[64];
+        secp256k1_pubkey pub_decoded;
+        secp256k1_ge ge_decoded;
+
+        /* Construct ellswift pubkey from exhaustive loop scalar i. */
+        secp256k1_scalar_set_int(&scalar_i, i);
+        secp256k1_scalar_get_b32(sec32, &scalar_i);
+        CHECK(secp256k1_ellswift_create(ctx, ell64, sec32, NULL));
+
+        /* Decode ellswift pubkey and check that it matches the precomputed group element. */
+        secp256k1_ellswift_decode(ctx, &pub_decoded, ell64);
+        secp256k1_pubkey_load(ctx, &ge_decoded, &pub_decoded);
+        CHECK(secp256k1_ge_eq_var(&ge_decoded, &group[i]));
+    }
+}
+
+#endif

src/modules/ellswift/tests_impl.h

@@ -0,0 +1,436 @@
+/***********************************************************************
+ * Distributed under the MIT software license, see the accompanying    *
+ * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
+ ***********************************************************************/
+
+#ifndef SECP256K1_MODULE_ELLSWIFT_TESTS_H
+#define SECP256K1_MODULE_ELLSWIFT_TESTS_H
+
+#include "../../../include/secp256k1_ellswift.h"
+
+struct ellswift_xswiftec_inv_test {
+    int enc_bitmap;
+    secp256k1_fe u;
+    secp256k1_fe x;
+    secp256k1_fe encs[8];
+};
+
+struct ellswift_decode_test {
+    unsigned char enc[64];
+    secp256k1_fe x;
+    int odd_y;
+};
+
+struct ellswift_xdh_test {
+    unsigned char priv_ours[32];
+    unsigned char ellswift_ours[64];
+    unsigned char ellswift_theirs[64];
+    int initiating;
+    unsigned char shared_secret[32];
+};
+
+/* Set of (point, encodings) test vectors, selected to maximize branch coverage, part of the BIP324
+ * test vectors. Created using an independent implementation, and tested decoding against paper
+ * authors' code. */
+static const struct ellswift_xswiftec_inv_test ellswift_xswiftec_inv_tests[] = {
+    {0xcc, SECP256K1_FE_CONST(0x05ff6bda, 0xd900fc32, 0x61bc7fe3, 0x4e2fb0f5, 0x69f06e09, 0x1ae437d3, 0xa52e9da0, 0xcbfb9590), SECP256K1_FE_CONST(0x80cdf637, 0x74ec7022, 0xc89a5a85, 0x58e373a2, 0x79170285, 0xe0ab2741, 0x2dbce510, 0xbdfe23fc), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x45654798, 0xece071ba, 0x79286d04, 0xf7f3eb1c, 0x3f1d17dd, 0x883610f2, 0xad2efd82, 0xa287466b), SECP256K1_FE_CONST(0x0aeaa886, 0xf6b76c71, 0x58452418, 0xcbf5033a, 0xdc5747e9, 0xe9b5d3b2, 0x303db969, 0x36528557), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xba9ab867, 0x131f8e45, 0x86d792fb, 0x080c14e3, 0xc0e2e822, 0x77c9ef0d, 0x52d1027c, 0x5d78b5c4), SECP256K1_FE_CONST(0xf5155779, 0x0948938e, 0xa7badbe7, 0x340afcc5, 0x23a8b816, 0x164a2c4d, 0xcfc24695, 0xc9ad76d8)}},
+    {0x33, SECP256K1_FE_CONST(0x1737a85f, 0x4c8d146c, 0xec96e3ff, 0xdca76d99, 0x03dcf3bd, 0x53061868, 0xd478c78c, 0x63c2aa9e), SECP256K1_FE_CONST(0x39e48dd1, 0x50d2f429, 0xbe088dfd, 0x5b61882e, 0x7e840748, 0x3702ae9a, 0x5ab35927, 0xb15f85ea), {SECP256K1_FE_CONST(0x1be8cc0b, 0x04be0c68, 0x1d0c6a68, 0xf733f82c, 0x6c896e0c, 0x8a262fcd, 0x392918e3, 0x03a7abf4), SECP256K1_FE_CONST(0x605b5814, 0xbf9b8cb0, 0x66667c9e, 0x5480d22d, 0xc5b6c92f, 0x14b4af3e, 0xe0a9eb83, 0xb03685e3), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xe41733f4, 0xfb41f397, 0xe2f39597, 0x08cc07d3, 0x937691f3, 0x75d9d032, 0xc6d6e71b, 0xfc58503b), SECP256K1_FE_CONST(0x9fa4a7eb, 0x4064734f, 0x99998361, 0xab7f2dd2, 0x3a4936d0, 0xeb4b50c1, 0x1f56147b, 0x4fc9764c), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0x1aaa1cce, 0xbf9c7241, 0x91033df3, 0x66b36f69, 0x1c4d902c, 0x228033ff, 0x4516d122, 0xb2564f68), SECP256K1_FE_CONST(0xc7554125, 0x9d3ba98f, 0x207eaa30, 0xc69634d1, 0x87d0b6da, 0x594e719e, 0x420f4898, 0x638fc5b0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x33, SECP256K1_FE_CONST(0x2323a1d0, 0x79b0fd72, 0xfc8bb62e, 0xc34230a8, 0x15cb0596, 0xc2bfac99, 0x8bd6b842, 0x60f5dc26), SECP256K1_FE_CONST(0x239342df, 0xb675500a, 0x34a19631, 0x0b8d87d5, 0x4f49dcac, 0x9da50c17, 0x43ceab41, 0xa7b249ff), {SECP256K1_FE_CONST(0xf63580b8, 0xaa49c484, 0x6de56e39, 0xe1b3e73f, 0x171e881e, 0xba8c66f6, 0x14e67e5c, 0x975dfc07), SECP256K1_FE_CONST(0xb6307b33, 0x2e699f1c, 0xf77841d9, 0x0af25365, 0x404deb7f, 0xed5edb30, 0x90db49e6, 0x42a156b6), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x09ca7f47, 0x55b63b7b, 0x921a91c6, 0x1e4c18c0, 0xe8e177e1, 0x45739909, 0xeb1981a2, 0x68a20028), SECP256K1_FE_CONST(0x49cf84cc, 0xd19660e3, 0x0887be26, 0xf50dac9a, 0xbfb21480, 0x12a124cf, 0x6f24b618, 0xbd5ea579), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x33, SECP256K1_FE_CONST(0x2dc90e64, 0x0cb646ae, 0x9164c0b5, 0xa9ef0169, 0xfebe34dc, 0x4437d6e4, 0x6acb0e27, 0xe219d1e8), SECP256K1_FE_CONST(0xd236f19b, 0xf349b951, 0x6e9b3f4a, 0x5610fe96, 0x0141cb23, 0xbbc8291b, 0x9534f1d7, 0x1de62a47), {SECP256K1_FE_CONST(0xe69df7d9, 0xc026c366, 0x00ebdf58, 0x80726758, 0x47c0c431, 0xc8eb7306, 0x82533e96, 0x4b6252c9), SECP256K1_FE_CONST(0x4f18bbdf, 0x7c2d6c5f, 0x818c1880, 0x2fa35cd0, 0x69eaa79f, 0xff74e4fc, 0x837c80d9, 0x3fece2f8), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x19620826, 0x3fd93c99, 0xff1420a7, 0x7f8d98a7, 0xb83f3bce, 0x37148cf9, 0x7dacc168, 0xb49da966), SECP256K1_FE_CONST(0xb0e74420, 0x83d293a0, 0x7e73e77f, 0xd05ca32f, 0x96155860, 0x008b1b03, 0x7c837f25, 0xc0131937), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xcc, SECP256K1_FE_CONST(0x3edd7b39, 0x80e2f2f3, 0x4d1409a2, 0x07069f88, 0x1fda5f96, 0xf08027ac, 0x4465b63d, 0xc278d672), SECP256K1_FE_CONST(0x053a98de, 0x4a27b196, 0x1155822b, 0x3a3121f0, 0x3b2a1445, 0x8bd80eb4, 0xa560c4c7, 0xa85c149c), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb3dae4b7, 0xdcf858e4, 0xc6968057, 0xcef2b156, 0x46543152, 0x6538199c, 0xf52dc1b2, 0xd62fda30), SECP256K1_FE_CONST(0x4aa77dd5, 0x5d6b6d3c, 0xfa10cc9d, 0x0fe42f79, 0x232e4575, 0x661049ae, 0x36779c1d, 0x0c666d88), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x4c251b48, 0x2307a71b, 0x39697fa8, 0x310d4ea9, 0xb9abcead, 0x9ac7e663, 0x0ad23e4c, 0x29d021ff), SECP256K1_FE_CONST(0xb558822a, 0xa29492c3, 0x05ef3362, 0xf01bd086, 0xdcd1ba8a, 0x99efb651, 0xc98863e1, 0xf3998ea7)}},
+    {0x00, SECP256K1_FE_CONST(0x4295737e, 0xfcb1da6f, 0xb1d96b9c, 0xa7dcd1e3, 0x20024b37, 0xa736c494, 0x8b625981, 0x73069f70), SECP256K1_FE_CONST(0xfa7ffe4f, 0x25f88362, 0x831c087a, 0xfe2e8a9b, 0x0713e2ca, 0xc1ddca6a, 0x383205a2, 0x66f14307), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xff, SECP256K1_FE_CONST(0x587c1a0c, 0xee91939e, 0x7f784d23, 0xb963004a, 0x3bf44f5d, 0x4e32a008, 0x1995ba20, 0xb0fca59e), SECP256K1_FE_CONST(0x2ea98853, 0x0715e8d1, 0x0363907f, 0xf2512452, 0x4d471ba2, 0x454d5ce3, 0xbe3f0419, 0x4dfd3a3c), {SECP256K1_FE_CONST(0xcfd5a094, 0xaa0b9b88, 0x91b76c6a, 0xb9438f66, 0xaa1c095a, 0x65f9f701, 0x35e81712, 0x92245e74), SECP256K1_FE_CONST(0xa89057d7, 0xc6563f0d, 0x6efa19ae, 0x84412b8a, 0x7b47e791, 0xa191ecdf, 0xdf2af84f, 0xd97bc339), SECP256K1_FE_CONST(0x475d0ae9, 0xef46920d, 0xf07b3411, 0x7be5a081, 0x7de1023e, 0x3cc32689, 0xe9be145b, 0x406b0aef), SECP256K1_FE_CONST(0xa0759178, 0xad802324, 0x54f827ef, 0x05ea3e72, 0xad8d7541, 0x8e6d4cc1, 0xcd4f5306, 0xc5e7c453), SECP256K1_FE_CONST(0x302a5f6b, 0x55f46477, 0x6e489395, 0x46bc7099, 0x55e3f6a5, 0x9a0608fe, 0xca17e8ec, 0x6ddb9dbb), SECP256K1_FE_CONST(0x576fa828, 0x39a9c0f2, 0x9105e651, 0x7bbed475, 0x84b8186e, 0x5e6e1320, 0x20d507af, 0x268438f6), SECP256K1_FE_CONST(0xb8a2f516, 0x10b96df2, 0x0f84cbee, 0x841a5f7e, 0x821efdc1, 0xc33cd976, 0x1641eba3, 0xbf94f140), SECP256K1_FE_CONST(0x5f8a6e87, 0x527fdcdb, 0xab07d810, 0xfa15c18d, 0x52728abe, 0x7192b33e, 0x32b0acf8, 0x3a1837dc)}},
+    {0xcc, SECP256K1_FE_CONST(0x5fa88b33, 0x65a635cb, 0xbcee003c, 0xce9ef51d, 0xd1a310de, 0x277e441a, 0xbccdb7be, 0x1e4ba249), SECP256K1_FE_CONST(0x79461ff6, 0x2bfcbcac, 0x4249ba84, 0xdd040f2c, 0xec3c63f7, 0x25204dc7, 0xf464c16b, 0xf0ff3170), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x6bb700e1, 0xf4d7e236, 0xe8d193ff, 0x4a76c1b3, 0xbcd4e2b2, 0x5acac3d5, 0x1c8dac65, 0x3fe909a0), SECP256K1_FE_CONST(0xf4c73410, 0x633da7f6, 0x3a4f1d55, 0xaec6dd32, 0xc4c6d89e, 0xe74075ed, 0xb5515ed9, 0x0da9e683), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x9448ff1e, 0x0b281dc9, 0x172e6c00, 0xb5893e4c, 0x432b1d4d, 0xa5353c2a, 0xe3725399, 0xc016f28f), SECP256K1_FE_CONST(0x0b38cbef, 0x9cc25809, 0xc5b0e2aa, 0x513922cd, 0x3b392761, 0x18bf8a12, 0x4aaea125, 0xf25615ac)}},
+    {0xcc, SECP256K1_FE_CONST(0x6fb31c75, 0x31f03130, 0xb42b155b, 0x952779ef, 0xbb46087d, 0xd9807d24, 0x1a48eac6, 0x3c3d96d6), SECP256K1_FE_CONST(0x56f81be7, 0x53e8d4ae, 0x4940ea6f, 0x46f6ec9f, 0xda66a6f9, 0x6cc95f50, 0x6cb2b574, 0x90e94260), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x59059774, 0x795bdb7a, 0x837fbe11, 0x40a5fa59, 0x984f48af, 0x8df95d57, 0xdd6d1c05, 0x437dcec1), SECP256K1_FE_CONST(0x22a644db, 0x79376ad4, 0xe7b3a009, 0xe58b3f13, 0x137c54fd, 0xf911122c, 0xc93667c4, 0x7077d784), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xa6fa688b, 0x86a42485, 0x7c8041ee, 0xbf5a05a6, 0x67b0b750, 0x7206a2a8, 0x2292e3f9, 0xbc822d6e), SECP256K1_FE_CONST(0xdd59bb24, 0x86c8952b, 0x184c5ff6, 0x1a74c0ec, 0xec83ab02, 0x06eeedd3, 0x36c9983a, 0x8f8824ab)}},
+    {0x00, SECP256K1_FE_CONST(0x704cd226, 0xe71cb682, 0x6a590e80, 0xdac90f2d, 0x2f5830f0, 0xfdf135a3, 0xeae3965b, 0xff25ff12), SECP256K1_FE_CONST(0x138e0afa, 0x68936ee6, 0x70bd2b8d, 0xb53aedbb, 0x7bea2a85, 0x97388b24, 0xd0518edd, 0x22ad66ec), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x33, SECP256K1_FE_CONST(0x725e9147, 0x92cb8c89, 0x49e7e116, 0x8b7cdd8a, 0x8094c91c, 0x6ec2202c, 0xcd53a6a1, 0x8771edeb), SECP256K1_FE_CONST(0x8da16eb8, 0x6d347376, 0xb6181ee9, 0x74832275, 0x7f6b36e3, 0x913ddfd3, 0x32ac595d, 0x788e0e44), {SECP256K1_FE_CONST(0xdd357786, 0xb9f68733, 0x30391aa5, 0x62580965, 0x4e43116e, 0x82a5a5d8, 0x2ffd1d66, 0x24101fc4), SECP256K1_FE_CONST(0xa0b7efca, 0x01814594, 0xc59c9aae, 0x8e497001, 0x86ca5d95, 0xe88bcc80, 0x399044d9, 0xc2d8613d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x22ca8879, 0x460978cc, 0xcfc6e55a, 0x9da7f69a, 0xb1bcee91, 0x7d5a5a27, 0xd002e298, 0xdbefdc6b), SECP256K1_FE_CONST(0x5f481035, 0xfe7eba6b, 0x3a636551, 0x71b68ffe, 0x7935a26a, 0x1774337f, 0xc66fbb25, 0x3d279af2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0x78fe6b71, 0x7f2ea4a3, 0x2708d79c, 0x151bf503, 0xa5312a18, 0xc0963437, 0xe865cc6e, 0xd3f6ae97), SECP256K1_FE_CONST(0x8701948e, 0x80d15b5c, 0xd8f72863, 0xeae40afc, 0x5aced5e7, 0x3f69cbc8, 0x179a3390, 0x2c094d98), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x44, SECP256K1_FE_CONST(0x7c37bb9c, 0x5061dc07, 0x413f11ac, 0xd5a34006, 0xe64c5c45, 0x7fdb9a43, 0x8f217255, 0xa961f50d), SECP256K1_FE_CONST(0x5c1a76b4, 0x4568eb59, 0xd6789a74, 0x42d9ed7c, 0xdc6226b7, 0x752b4ff8, 0xeaf8e1a9, 0x5736e507), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb94d30cd, 0x7dbff60b, 0x64620c17, 0xca0fafaa, 0x40b3d1f5, 0x2d077a60, 0xa2e0cafd, 0x145086c2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x46b2cf32, 0x824009f4, 0x9b9df3e8, 0x35f05055, 0xbf4c2e0a, 0xd2f8859f, 0x5d1f3501, 0xebaf756d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0x82388888, 0x967f82a6, 0xb444438a, 0x7d44838e, 0x13c0d478, 0xb9ca060d, 0xa95a41fb, 0x94303de6), SECP256K1_FE_CONST(0x29e96541, 0x70628fec, 0x8b497289, 0x8b113cf9, 0x8807f460, 0x9274f4f3, 0x140d0674, 0x157c90a0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x33, SECP256K1_FE_CONST(0x91298f57, 0x70af7a27, 0xf0a47188, 0xd24c3b7b, 0xf98ab299, 0x0d84b0b8, 0x98507e3c, 0x561d6472), SECP256K1_FE_CONST(0x144f4ccb, 0xd9a74698, 0xa88cbf6f, 0xd00ad886, 0xd339d29e, 0xa19448f2, 0xc572cac0, 0xa07d5562), {SECP256K1_FE_CONST(0xe6a0ffa3, 0x807f09da, 0xdbe71e0f, 0x4be4725f, 0x2832e76c, 0xad8dc1d9, 0x43ce8393, 0x75eff248), SECP256K1_FE_CONST(0x837b8e68, 0xd4917544, 0x764ad090, 0x3cb11f86, 0x15d2823c, 0xefbb06d8, 0x9049dbab, 0xc69befda), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x195f005c, 0x7f80f625, 0x2418e1f0, 0xb41b8da0, 0xd7cd1893, 0x52723e26, 0xbc317c6b, 0x8a1009e7), SECP256K1_FE_CONST(0x7c847197, 0x2b6e8abb, 0x89b52f6f, 0xc34ee079, 0xea2d7dc3, 0x1044f927, 0x6fb62453, 0x39640c55), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0xb682f3d0, 0x3bbb5dee, 0x4f54b5eb, 0xfba931b4, 0xf52f6a19, 0x1e5c2f48, 0x3c73c66e, 0x9ace97e1), SECP256K1_FE_CONST(0x904717bf, 0x0bc0cb78, 0x73fcdc38, 0xaa97f19e, 0x3a626309, 0x72acff92, 0xb24cc6dd, 0xa197cb96), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x77, SECP256K1_FE_CONST(0xc17ec69e, 0x665f0fb0, 0xdbab48d9, 0xc2f94d12, 0xec8a9d7e, 0xacb58084, 0x83309180, 0x1eb0b80b), SECP256K1_FE_CONST(0x147756e6, 0x6d96e31c, 0x426d3cc8, 0x5ed0c4cf, 0xbef6341d, 0xd8b28558, 0x5aa574ea, 0x0204b55e), {SECP256K1_FE_CONST(0x6f4aea43, 0x1a0043bd, 0xd03134d6, 0xd9159119, 0xce034b88, 0xc32e50e8, 0xe36c4ee4, 0x5eac7ae9), SECP256K1_FE_CONST(0xfd5be16d, 0x4ffa2690, 0x126c67c3, 0xef7cb9d2, 0x9b74d397, 0xc78b06b3, 0x605fda34, 0xdc9696a6), SECP256K1_FE_CONST(0x5e9c6079, 0x2a2f000e, 0x45c6250f, 0x296f875e, 0x174efc0e, 0x9703e628, 0x706103a9, 0xdd2d82c7), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x90b515bc, 0xe5ffbc42, 0x2fcecb29, 0x26ea6ee6, 0x31fcb477, 0x3cd1af17, 0x1c93b11a, 0xa1538146), SECP256K1_FE_CONST(0x02a41e92, 0xb005d96f, 0xed93983c, 0x1083462d, 0x648b2c68, 0x3874f94c, 0x9fa025ca, 0x23696589), SECP256K1_FE_CONST(0xa1639f86, 0xd5d0fff1, 0xba39daf0, 0xd69078a1, 0xe8b103f1, 0x68fc19d7, 0x8f9efc55, 0x22d27968), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xcc, SECP256K1_FE_CONST(0xc25172fc, 0x3f29b6fc, 0x4a1155b8, 0x57523315, 0x5486b274, 0x64b74b8b, 0x260b499a, 0x3f53cb14), SECP256K1_FE_CONST(0x1ea9cbdb, 0x35cf6e03, 0x29aa31b0, 0xbb0a702a, 0x65123ed0, 0x08655a93, 0xb7dcd528, 0x0e52e1ab), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x7422edc7, 0x843136af, 0x0053bb88, 0x54448a82, 0x99994f9d, 0xdcefd3a9, 0xa92d4546, 0x2c59298a), SECP256K1_FE_CONST(0x78c7774a, 0x266f8b97, 0xea23d05d, 0x064f033c, 0x77319f92, 0x3f6b78bc, 0xe4e20bf0, 0x5fa5398d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x8bdd1238, 0x7bcec950, 0xffac4477, 0xabbb757d, 0x6666b062, 0x23102c56, 0x56d2bab8, 0xd3a6d2a5), SECP256K1_FE_CONST(0x873888b5, 0xd9907468, 0x15dc2fa2, 0xf9b0fcc3, 0x88ce606d, 0xc0948743, 0x1b1df40e, 0xa05ac2a2)}},
+    {0x00, SECP256K1_FE_CONST(0xcab6626f, 0x832a4b12, 0x80ba7add, 0x2fc5322f, 0xf011caed, 0xedf7ff4d, 0xb6735d50, 0x26dc0367), SECP256K1_FE_CONST(0x2b2bef08, 0x52c6f7c9, 0x5d72ac99, 0xa23802b8, 0x75029cd5, 0x73b248d1, 0xf1b3fc80, 0x33788eb6), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x33, SECP256K1_FE_CONST(0xd8621b4f, 0xfc85b9ed, 0x56e99d8d, 0xd1dd24ae, 0xdcecb147, 0x63b861a1, 0x7112dc77, 0x1a104fd2), SECP256K1_FE_CONST(0x812cabe9, 0x72a22aa6, 0x7c7da0c9, 0x4d8a9362, 0x96eb9949, 0xd70c37cb, 0x2b248757, 0x4cb3ce58), {SECP256K1_FE_CONST(0xfbc5febc, 0x6fdbc9ae, 0x3eb88a93, 0xb982196e, 0x8b6275a6, 0xd5a73c17, 0x387e000c, 0x711bd0e3), SECP256K1_FE_CONST(0x8724c96b, 0xd4e5527f, 0x2dd195a5, 0x1c468d2d, 0x211ba2fa, 0xc7cbe0b4, 0xb3434253, 0x409fb42d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x043a0143, 0x90243651, 0xc147756c, 0x467de691, 0x749d8a59, 0x2a58c3e8, 0xc781fff2, 0x8ee42b4c), SECP256K1_FE_CONST(0x78db3694, 0x2b1aad80, 0xd22e6a5a, 0xe3b972d2, 0xdee45d05, 0x38341f4b, 0x4cbcbdab, 0xbf604802), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0xda463164, 0xc6f4bf71, 0x29ee5f0e, 0xc00f65a6, 0x75a8adf1, 0xbd931b39, 0xb64806af, 0xdcda9a22), SECP256K1_FE_CONST(0x25b9ce9b, 0x390b408e, 0xd611a0f1, 0x3ff09a59, 0x8a57520e, 0x426ce4c6, 0x49b7f94f, 0x2325620d), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xcc, SECP256K1_FE_CONST(0xdafc971e, 0x4a3a7b6d, 0xcfb42a08, 0xd9692d82, 0xad9e7838, 0x523fcbda, 0x1d4827e1, 0x4481ae2d), SECP256K1_FE_CONST(0x250368e1, 0xb5c58492, 0x304bd5f7, 0x2696d27d, 0x526187c7, 0xadc03425, 0xe2b7d81d, 0xbb7e4e02), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x370c28f1, 0xbe665efa, 0xcde6aa43, 0x6bf86fe2, 0x1e6e314c, 0x1e53dd04, 0x0e6c73a4, 0x6b4c8c49), SECP256K1_FE_CONST(0xcd8acee9, 0x8ffe5653, 0x1a84d7eb, 0x3e48fa40, 0x34206ce8, 0x25ace907, 0xd0edf0ea, 0xeb5e9ca2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xc8f3d70e, 0x4199a105, 0x321955bc, 0x9407901d, 0xe191ceb3, 0xe1ac22fb, 0xf1938c5a, 0x94b36fe6), SECP256K1_FE_CONST(0x32753116, 0x7001a9ac, 0xe57b2814, 0xc1b705bf, 0xcbdf9317, 0xda5316f8, 0x2f120f14, 0x14a15f8d)}},
+    {0x44, SECP256K1_FE_CONST(0xe0294c8b, 0xc1a36b41, 0x66ee92bf, 0xa70a5c34, 0x976fa982, 0x9405efea, 0x8f9cd54d, 0xcb29b99e), SECP256K1_FE_CONST(0xae9690d1, 0x3b8d20a0, 0xfbbf37be, 0xd8474f67, 0xa04e142f, 0x56efd787, 0x70a76b35, 0x9165d8a1), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xdcd45d93, 0x5613916a, 0xf167b029, 0x058ba3a7, 0x00d37150, 0xb9df3472, 0x8cb05412, 0xc16d4182), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x232ba26c, 0xa9ec6e95, 0x0e984fd6, 0xfa745c58, 0xff2c8eaf, 0x4620cb8d, 0x734fabec, 0x3e92baad), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0x00, SECP256K1_FE_CONST(0xe148441c, 0xd7b92b8b, 0x0e4fa3bd, 0x68712cfd, 0x0d709ad1, 0x98cace61, 0x1493c10e, 0x97f5394e), SECP256K1_FE_CONST(0x164a6397, 0x94d74c53, 0xafc4d329, 0x4e79cdb3, 0xcd25f99f, 0x6df45c00, 0x0f758aba, 0x54d699c0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xff, SECP256K1_FE_CONST(0xe4b00ec9, 0x7aadcca9, 0x7644d3b0, 0xc8a931b1, 0x4ce7bcf7, 0xbc877954, 0x6d6e35aa, 0x5937381c), SECP256K1_FE_CONST(0x94e9588d, 0x41647b3f, 0xcc772dc8, 0xd83c67ce, 0x3be00353, 0x8517c834, 0x103d2cd4, 0x9d62ef4d), {SECP256K1_FE_CONST(0xc88d25f4, 0x1407376b, 0xb2c03a7f, 0xffeb3ec7, 0x811cc434, 0x91a0c3aa, 0xc0378cdc, 0x78357bee), SECP256K1_FE_CONST(0x51c02636, 0xce00c234, 0x5ecd89ad, 0xb6089fe4, 0xd5e18ac9, 0x24e3145e, 0x6669501c, 0xd37a00d4), SECP256K1_FE_CONST(0x205b3512, 0xdb40521c, 0xb200952e, 0x67b46f67, 0xe09e7839, 0xe0de4400, 0x4138329e, 0xbd9138c5), SECP256K1_FE_CONST(0x58aab390, 0xab6fb55c, 0x1d1b8089, 0x7a207ce9, 0x4a78fa5b, 0x4aa61a33, 0x398bcae9, 0xadb20d3e), SECP256K1_FE_CONST(0x3772da0b, 0xebf8c894, 0x4d3fc580, 0x0014c138, 0x7ee33bcb, 0x6e5f3c55, 0x3fc87322, 0x87ca8041), SECP256K1_FE_CONST(0xae3fd9c9, 0x31ff3dcb, 0xa1327652, 0x49f7601b, 0x2a1e7536, 0xdb1ceba1, 0x9996afe2, 0x2c85fb5b), SECP256K1_FE_CONST(0xdfa4caed, 0x24bfade3, 0x4dff6ad1, 0x984b9098, 0x1f6187c6, 0x1f21bbff, 0xbec7cd60, 0x426ec36a), SECP256K1_FE_CONST(0xa7554c6f, 0x54904aa3, 0xe2e47f76, 0x85df8316, 0xb58705a4, 0xb559e5cc, 0xc6743515, 0x524deef1)}},
+    {0x00, SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xff, SECP256K1_FE_CONST(0xe6bcb5c3, 0xd63467d4, 0x90bfa54f, 0xbbc6092a, 0x7248c25e, 0x11b248dc, 0x2964a6e1, 0x5edb1457), SECP256K1_FE_CONST(0x19434a3c, 0x29cb982b, 0x6f405ab0, 0x4439f6d5, 0x8db73da1, 0xee4db723, 0xd69b591d, 0xa124e7d8), {SECP256K1_FE_CONST(0x67119877, 0x832ab8f4, 0x59a82165, 0x6d8261f5, 0x44a553b8, 0x9ae4f25c, 0x52a97134, 0xb70f3426), SECP256K1_FE_CONST(0xffee02f5, 0xe649c07f, 0x0560eff1, 0x867ec7b3, 0x2d0e595e, 0x9b1c0ea6, 0xe2a4fc70, 0xc97cd71f), SECP256K1_FE_CONST(0xb5e0c189, 0xeb5b4bac, 0xd025b744, 0x4d74178b, 0xe8d5246c, 0xfa4a9a20, 0x7964a057, 0xee969992), SECP256K1_FE_CONST(0x5746e459, 0x1bf7f4c3, 0x044609ea, 0x372e9086, 0x03975d27, 0x9fdef834, 0x9f0b08d3, 0x2f07619d), SECP256K1_FE_CONST(0x98ee6788, 0x7cd5470b, 0xa657de9a, 0x927d9e0a, 0xbb5aac47, 0x651b0da3, 0xad568eca, 0x48f0c809), SECP256K1_FE_CONST(0x0011fd0a, 0x19b63f80, 0xfa9f100e, 0x7981384c, 0xd2f1a6a1, 0x64e3f159, 0x1d5b038e, 0x36832510), SECP256K1_FE_CONST(0x4a1f3e76, 0x14a4b453, 0x2fda48bb, 0xb28be874, 0x172adb93, 0x05b565df, 0x869b5fa7, 0x1169629d), SECP256K1_FE_CONST(0xa8b91ba6, 0xe4080b3c, 0xfbb9f615, 0xc8d16f79, 0xfc68a2d8, 0x602107cb, 0x60f4f72b, 0xd0f89a92)}},
+    {0x33, SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), {SECP256K1_FE_CONST(0x4f867ad8, 0xbb3d8404, 0x09d26b67, 0x307e6210, 0x0153273f, 0x72fa4b74, 0x84becfa1, 0x4ebe7408), SECP256K1_FE_CONST(0x5bbc4f59, 0xe452cc5f, 0x22a99144, 0xb10ce898, 0x9a89a995, 0xec3cea1c, 0x91ae10e8, 0xf721bb5d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb0798527, 0x44c27bfb, 0xf62d9498, 0xcf819def, 0xfeacd8c0, 0x8d05b48b, 0x7b41305d, 0xb1418827), SECP256K1_FE_CONST(0xa443b0a6, 0x1bad33a0, 0xdd566ebb, 0x4ef31767, 0x6576566a, 0x13c315e3, 0x6e51ef16, 0x08de40d2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+    {0xcc, SECP256K1_FE_CONST(0xf455605b, 0xc85bf48e, 0x3a908c31, 0x023faf98, 0x381504c6, 0xc6d3aeb9, 0xede55f8d, 0xd528924d), SECP256K1_FE_CONST(0xd31fbcd5, 0xcdb798f6, 0xc00db669, 0x2f8fe896, 0x7fa9c79d, 0xd10958f4, 0xa194f013, 0x74905e99), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x0c00c571, 0x5b56fe63, 0x2d814ad8, 0xa77f8e66, 0x628ea47a, 0x6116834f, 0x8c1218f3, 0xa03cbd50), SECP256K1_FE_CONST(0xdf88e44f, 0xac84fa52, 0xdf4d59f4, 0x8819f18f, 0x6a8cd415, 0x1d162afa, 0xf773166f, 0x57c7ff46), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xf3ff3a8e, 0xa4a9019c, 0xd27eb527, 0x58807199, 0x9d715b85, 0x9ee97cb0, 0x73ede70b, 0x5fc33edf), SECP256K1_FE_CONST(0x20771bb0, 0x537b05ad, 0x20b2a60b, 0x77e60e70, 0x95732bea, 0xe2e9d505, 0x088ce98f, 0xa837fce9)}},
+    {0xff, SECP256K1_FE_CONST(0xf58cd4d9, 0x830bad32, 0x2699035e, 0x8246007d, 0x4be27e19, 0xb6f53621, 0x317b4f30, 0x9b3daa9d), SECP256K1_FE_CONST(0x78ec2b3d, 0xc0948de5, 0x60148bbc, 0x7c6dc963, 0x3ad5df70, 0xa5a5750c, 0xbed72180, 0x4f082a3b), {SECP256K1_FE_CONST(0x6c4c580b, 0x76c75940, 0x43569f9d, 0xae16dc28, 0x01c16a1f, 0xbe128608, 0x81b75f8e, 0xf929bce5), SECP256K1_FE_CONST(0x94231355, 0xe7385c5f, 0x25ca436a, 0xa6419147, 0x1aea4393, 0xd6e86ab7, 0xa35fe2af, 0xacaefd0d), SECP256K1_FE_CONST(0xdff2a195, 0x1ada6db5, 0x74df8340, 0x48149da3, 0x397a75b8, 0x29abf58c, 0x7e69db1b, 0x41ac0989), SECP256K1_FE_CONST(0xa52b66d3, 0xc9070355, 0x48028bf8, 0x04711bf4, 0x22aba95f, 0x1a666fc8, 0x6f4648e0, 0x5f29caae), SECP256K1_FE_CONST(0x93b3a7f4, 0x8938a6bf, 0xbca96062, 0x51e923d7, 0xfe3e95e0, 0x41ed79f7, 0x7e48a070, 0x06d63f4a), SECP256K1_FE_CONST(0x6bdcecaa, 0x18c7a3a0, 0xda35bc95, 0x59be6eb8, 0xe515bc6c, 0x29179548, 0x5ca01d4f, 0x5350ff22), SECP256K1_FE_CONST(0x200d5e6a, 0xe525924a, 0x8b207cbf, 0xb7eb625c, 0xc6858a47, 0xd6540a73, 0x819624e3, 0xbe53f2a6), SECP256K1_FE_CONST(0x5ad4992c, 0x36f8fcaa, 0xb7fd7407, 0xfb8ee40b, 0xdd5456a0, 0xe5999037, 0x90b9b71e, 0xa0d63181)}},
+    {0x00, SECP256K1_FE_CONST(0xfd7d912a, 0x40f182a3, 0x588800d6, 0x9ebfb504, 0x8766da20, 0x6fd7ebc8, 0xd2436c81, 0xcbef6421), SECP256K1_FE_CONST(0x8d37c862, 0x054debe7, 0x31694536, 0xff46b273, 0xec122b35, 0xa9bf1445, 0xac3c4ff9, 0xf262c952), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}},
+};
+
+/* Set of (encoding, xcoord) test vectors, selected to maximize branch coverage, part of the BIP324
+ * test vectors. Created using an independent implementation, and tested decoding against the paper
+ * authors' code. */
+static const struct ellswift_decode_test ellswift_decode_tests[] = {
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xbd, 0xe7, 0x0d, 0xf5, 0x19, 0x39, 0xb9, 0x4c, 0x9c, 0x24, 0x97, 0x9f, 0xa7, 0xdd, 0x04, 0xeb, 0xd9, 0xb3, 0x57, 0x2d, 0xa7, 0x80, 0x22, 0x90, 0x43, 0x8a, 0xf2, 0xa6, 0x81, 0x89, 0x54, 0x41}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 1},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0},
+    {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0},
+    {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0},
+    {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0},
+    {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x74e880b3, 0xffd18fe3, 0xcddf7902, 0x522551dd, 0xf97fa4a3, 0x5a3cfda8, 0x197f9470, 0x81a57b8f), 0},
+    {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x377b643f, 0xce2271f6, 0x4e5c8101, 0x566107c1, 0xbe498074, 0x50917838, 0x04f65478, 0x1ac9217c), 1},
+    {{0x12, 0x36, 0x58, 0x44, 0x4f, 0x32, 0xbe, 0x8f, 0x02, 0xea, 0x20, 0x34, 0xaf, 0xa7, 0xef, 0x4b, 0xbe, 0x8a, 0xdc, 0x91, 0x8c, 0xeb, 0x49, 0xb1, 0x27, 0x73, 0xb6, 0x25, 0xf4, 0x90, 0xb3, 0x68, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8d, 0xc5, 0xfe, 0x11}, SECP256K1_FE_CONST(0xed16d65c, 0xf3a9538f, 0xcb2c139f, 0x1ecbc143, 0xee148271, 0x20cbc265, 0x9e667256, 0x800b8142), 0},
+    {{0x14, 0x6f, 0x92, 0x46, 0x4d, 0x15, 0xd3, 0x6e, 0x35, 0x38, 0x2b, 0xd3, 0xca, 0x5b, 0x0f, 0x97, 0x6c, 0x95, 0xcb, 0x08, 0xac, 0xdc, 0xf2, 0xd5, 0xb3, 0x57, 0x06, 0x17, 0x99, 0x08, 0x39, 0xd7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x31, 0x45, 0xe9, 0x3b}, SECP256K1_FE_CONST(0x0d5cd840, 0x427f941f, 0x65193079, 0xab8e2e83, 0x024ef2ee, 0x7ca558d8, 0x8879ffd8, 0x79fb6657), 0},
+    {{0x15, 0xfd, 0xf5, 0xcf, 0x09, 0xc9, 0x07, 0x59, 0xad, 0xd2, 0x27, 0x2d, 0x57, 0x4d, 0x2b, 0xb5, 0xfe, 0x14, 0x29, 0xf9, 0xf3, 0xc1, 0x4c, 0x65, 0xe3, 0x19, 0x4b, 0xf6, 0x1b, 0x82, 0xaa, 0x73, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x04, 0xcf, 0xd9, 0x06}, SECP256K1_FE_CONST(0x16d0e439, 0x46aec93f, 0x62d57eb8, 0xcde68951, 0xaf136cf4, 0xb307938d, 0xd1447411, 0xe07bffe1), 1},
+    {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0},
+    {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0},
+    {{0x1f, 0xe1, 0xe5, 0xef, 0x3f, 0xce, 0xb5, 0xc1, 0x35, 0xab, 0x77, 0x41, 0x33, 0x3c, 0xe5, 0xa6, 0xe8, 0x0d, 0x68, 0x16, 0x76, 0x53, 0xf6, 0xb2, 0xb2, 0x4b, 0xcb, 0xcf, 0xaa, 0xaf, 0xf5, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x98bec3b2, 0xa351fa96, 0xcfd191c1, 0x77835193, 0x1b9e9ba9, 0xad1149f6, 0xd9eadca8, 0x0981b801), 0},
+    {{0x40, 0x56, 0xa3, 0x4a, 0x21, 0x0e, 0xec, 0x78, 0x92, 0xe8, 0x82, 0x06, 0x75, 0xc8, 0x60, 0x09, 0x9f, 0x85, 0x7b, 0x26, 0xaa, 0xd8, 0x54, 0x70, 0xee, 0x6d, 0x3c, 0xf1, 0x30, 0x4a, 0x9d, 0xcf, 0x37, 0x5e, 0x70, 0x37, 0x42, 0x71, 0xf2, 0x0b, 0x13, 0xc9, 0x98, 0x6e, 0xd7, 0xd3, 0xc1, 0x77, 0x99, 0x69, 0x8c, 0xfc, 0x43, 0x5d, 0xbe, 0xd3, 0xa9, 0xf3, 0x4b, 0x38, 0xc8, 0x23, 0xc2, 0xb4}, SECP256K1_FE_CONST(0x868aac20, 0x03b29dbc, 0xad1a3e80, 0x3855e078, 0xa89d1654, 0x3ac64392, 0xd1224172, 0x98cec76e), 0},
+    {{0x41, 0x97, 0xec, 0x37, 0x23, 0xc6, 0x54, 0xcf, 0xdd, 0x32, 0xab, 0x07, 0x55, 0x06, 0x64, 0x8b, 0x2f, 0xf5, 0x07, 0x03, 0x62, 0xd0, 0x1a, 0x4f, 0xff, 0x14, 0xb3, 0x36, 0xb7, 0x8f, 0x96, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb3, 0xab, 0x1e, 0x95}, SECP256K1_FE_CONST(0xba5a6314, 0x502a8952, 0xb8f456e0, 0x85928105, 0xf665377a, 0x8ce27726, 0xa5b0eb7e, 0xc1ac0286), 0},
+    {{0x47, 0xeb, 0x3e, 0x20, 0x8f, 0xed, 0xcd, 0xf8, 0x23, 0x4c, 0x94, 0x21, 0xe9, 0xcd, 0x9a, 0x7a, 0xe8, 0x73, 0xbf, 0xbd, 0xbc, 0x39, 0x37, 0x23, 0xd1, 0xba, 0x1e, 0x1e, 0x6a, 0x8e, 0x6b, 0x24, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7c, 0xd1, 0x2c, 0xb1}, SECP256K1_FE_CONST(0xd192d520, 0x07e541c9, 0x807006ed, 0x0468df77, 0xfd214af0, 0xa795fe11, 0x9359666f, 0xdcf08f7c), 0},
+    {{0x5e, 0xb9, 0x69, 0x6a, 0x23, 0x36, 0xfe, 0x2c, 0x3c, 0x66, 0x6b, 0x02, 0xc7, 0x55, 0xdb, 0x4c, 0x0c, 0xfd, 0x62, 0x82, 0x5c, 0x7b, 0x58, 0x9a, 0x7b, 0x7b, 0xb4, 0x42, 0xe1, 0x41, 0xc1, 0xd6, 0x93, 0x41, 0x3f, 0x00, 0x52, 0xd4, 0x9e, 0x64, 0xab, 0xec, 0x6d, 0x58, 0x31, 0xd6, 0x6c, 0x43, 0x61, 0x28, 0x30, 0xa1, 0x7d, 0xf1, 0xfe, 0x43, 0x83, 0xdb, 0x89, 0x64, 0x68, 0x10, 0x02, 0x21}, SECP256K1_FE_CONST(0xef6e1da6, 0xd6c7627e, 0x80f7a723, 0x4cb08a02, 0x2c1ee1cf, 0x29e4d0f9, 0x642ae924, 0xcef9eb38), 1},
+    {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0},
+    {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0},
+    {{0x85, 0x1b, 0x1c, 0xa9, 0x45, 0x49, 0x37, 0x1c, 0x4f, 0x1f, 0x71, 0x87, 0x32, 0x1d, 0x39, 0xbf, 0x51, 0xc6, 0xb7, 0xfb, 0x61, 0xf7, 0xcb, 0xf0, 0x27, 0xc9, 0xda, 0x62, 0x02, 0x1b, 0x7a, 0x65, 0xfc, 0x54, 0xc9, 0x68, 0x37, 0xfb, 0x22, 0xb3, 0x62, 0xed, 0xa6, 0x3e, 0xc5, 0x2e, 0xc8, 0x3d, 0x81, 0xbe, 0xdd, 0x16, 0x0c, 0x11, 0xb2, 0x2d, 0x96, 0x5d, 0x9f, 0x4a, 0x6d, 0x64, 0xd2, 0x51}, SECP256K1_FE_CONST(0x3e731051, 0xe12d3323, 0x7eb324f2, 0xaa5b16bb, 0x868eb49a, 0x1aa1fadc, 0x19b6e876, 0x1b5a5f7b), 1},
+    {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0},
+    {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0},
+    {{0xa0, 0xf1, 0x84, 0x92, 0x18, 0x3e, 0x61, 0xe8, 0x06, 0x3e, 0x57, 0x36, 0x06, 0x59, 0x14, 0x21, 0xb0, 0x6b, 0xc3, 0x51, 0x36, 0x31, 0x57, 0x8a, 0x73, 0xa3, 0x9c, 0x1c, 0x33, 0x06, 0x23, 0x9f, 0x2f, 0x32, 0x90, 0x4f, 0x0d, 0x2a, 0x33, 0xec, 0xca, 0x8a, 0x54, 0x51, 0x70, 0x5b, 0xb5, 0x37, 0xd3, 0xbf, 0x44, 0xe0, 0x71, 0x22, 0x60, 0x25, 0xcd, 0xbf, 0xd2, 0x49, 0xfe, 0x0f, 0x7a, 0xd6}, SECP256K1_FE_CONST(0x97a09cf1, 0xa2eae7c4, 0x94df3c6f, 0x8a9445bf, 0xb8c09d60, 0x832f9b0b, 0x9d5eabe2, 0x5fbd14b9), 0},
+    {{0xa1, 0xed, 0x0a, 0x0b, 0xd7, 0x9d, 0x8a, 0x23, 0xcf, 0xe4, 0xec, 0x5f, 0xef, 0x5b, 0xa5, 0xcc, 0xcf, 0xd8, 0x44, 0xe4, 0xff, 0x5c, 0xb4, 0xb0, 0xf2, 0xe7, 0x16, 0x27, 0x34, 0x1f, 0x1c, 0x5b, 0x17, 0xc4, 0x99, 0x24, 0x9e, 0x0a, 0xc0, 0x8d, 0x5d, 0x11, 0xea, 0x1c, 0x2c, 0x8c, 0xa7, 0x00, 0x16, 0x16, 0x55, 0x9a, 0x79, 0x94, 0xea, 0xde, 0xc9, 0xca, 0x10, 0xfb, 0x4b, 0x85, 0x16, 0xdc}, SECP256K1_FE_CONST(0x65a89640, 0x744192cd, 0xac64b2d2, 0x1ddf989c, 0xdac75007, 0x25b645be, 0xf8e2200a, 0xe39691f2), 0},
+    {{0xba, 0x94, 0x59, 0x4a, 0x43, 0x27, 0x21, 0xaa, 0x35, 0x80, 0xb8, 0x4c, 0x16, 0x1d, 0x0d, 0x13, 0x4b, 0xc3, 0x54, 0xb6, 0x90, 0x40, 0x4d, 0x7c, 0xd4, 0xec, 0x57, 0xc1, 0x6d, 0x3f, 0xbe, 0x98, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xea, 0x50, 0x7d, 0xd7}, SECP256K1_FE_CONST(0x5e0d7656, 0x4aae92cb, 0x347e01a6, 0x2afd389a, 0x9aa401c7, 0x6c8dd227, 0x543dc9cd, 0x0efe685a), 0},
+    {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x2d97f96c, 0xac882dfe, 0x73dc44db, 0x6ce0f1d3, 0x1d624135, 0x8dd5d74e, 0xb3d3b500, 0x03d24c2b), 0},
+    {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x65, 0x07, 0xd0, 0x9a}, SECP256K1_FE_CONST(0xe7008afe, 0x6e8cbd50, 0x55df120b, 0xd748757c, 0x686dadb4, 0x1cce75e4, 0xaddcc5e0, 0x2ec02b44), 1},
+    {{0xc5, 0x98, 0x1b, 0xae, 0x27, 0xfd, 0x84, 0x40, 0x1c, 0x72, 0xa1, 0x55, 0xe5, 0x70, 0x7f, 0xbb, 0x81, 0x1b, 0x2b, 0x62, 0x06, 0x45, 0xd1, 0x02, 0x8e, 0xa2, 0x70, 0xcb, 0xe0, 0xee, 0x22, 0x5d, 0x4b, 0x62, 0xaa, 0x4d, 0xca, 0x65, 0x06, 0xc1, 0xac, 0xdb, 0xec, 0xc0, 0x55, 0x25, 0x69, 0xb4, 0xb2, 0x14, 0x36, 0xa5, 0x69, 0x2e, 0x25, 0xd9, 0x0d, 0x3b, 0xc2, 0xeb, 0x7c, 0xe2, 0x40, 0x78}, SECP256K1_FE_CONST(0x948b40e7, 0x181713bc, 0x018ec170, 0x2d3d054d, 0x15746c59, 0xa7020730, 0xdd13ecf9, 0x85a010d7), 0},
+    {{0xc8, 0x94, 0xce, 0x48, 0xbf, 0xec, 0x43, 0x30, 0x14, 0xb9, 0x31, 0xa6, 0xad, 0x42, 0x26, 0xd7, 0xdb, 0xd8, 0xea, 0xa7, 0xb6, 0xe3, 0xfa, 0xa8, 0xd0, 0xef, 0x94, 0x05, 0x2b, 0xcf, 0x8c, 0xff, 0x33, 0x6e, 0xeb, 0x39, 0x19, 0xe2, 0xb4, 0xef, 0xb7, 0x46, 0xc7, 0xf7, 0x1b, 0xbc, 0xa7, 0xe9, 0x38, 0x32, 0x30, 0xfb, 0xbc, 0x48, 0xff, 0xaf, 0xe7, 0x7e, 0x8b, 0xcc, 0x69, 0x54, 0x24, 0x71}, SECP256K1_FE_CONST(0xf1c91acd, 0xc2525330, 0xf9b53158, 0x434a4d43, 0xa1c547cf, 0xf29f1550, 0x6f5da4eb, 0x4fe8fa5a), 1},
+    {{0xcb, 0xb0, 0xde, 0xab, 0x12, 0x57, 0x54, 0xf1, 0xfd, 0xb2, 0x03, 0x8b, 0x04, 0x34, 0xed, 0x9c, 0xb3, 0xfb, 0x53, 0xab, 0x73, 0x53, 0x91, 0x12, 0x99, 0x94, 0xa5, 0x35, 0xd9, 0x25, 0xf6, 0x73, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x872d81ed, 0x8831d999, 0x8b67cb71, 0x05243edb, 0xf86c10ed, 0xfebb786c, 0x110b02d0, 0x7b2e67cd), 0},
+    {{0xd9, 0x17, 0xb7, 0x86, 0xda, 0xc3, 0x56, 0x70, 0xc3, 0x30, 0xc9, 0xc5, 0xae, 0x59, 0x71, 0xdf, 0xb4, 0x95, 0xc8, 0xae, 0x52, 0x3e, 0xd9, 0x7e, 0xe2, 0x42, 0x01, 0x17, 0xb1, 0x71, 0xf4, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x20, 0x01, 0xf6, 0xf6}, SECP256K1_FE_CONST(0xe45b71e1, 0x10b831f2, 0xbdad8651, 0x994526e5, 0x8393fde4, 0x328b1ec0, 0x4d598971, 0x42584691), 1},
+    {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0},
+    {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0},
+    {{0xe7, 0xee, 0x58, 0x14, 0xc1, 0x70, 0x6b, 0xf8, 0xa8, 0x93, 0x96, 0xa9, 0xb0, 0x32, 0xbc, 0x01, 0x4c, 0x2c, 0xac, 0x9c, 0x12, 0x11, 0x27, 0xdb, 0xf6, 0xc9, 0x92, 0x78, 0xf8, 0xbb, 0x53, 0xd1, 0xdf, 0xd0, 0x4d, 0xbc, 0xda, 0x8e, 0x35, 0x24, 0x66, 0xb6, 0xfc, 0xd5, 0xf2, 0xde, 0xa3, 0xe1, 0x7d, 0x5e, 0x13, 0x31, 0x15, 0x88, 0x6e, 0xda, 0x20, 0xdb, 0x8a, 0x12, 0xb5, 0x4d, 0xe7, 0x1b}, SECP256K1_FE_CONST(0xe842c6e3, 0x529b2342, 0x70a5e977, 0x44edc34a, 0x04d7ba94, 0xe44b6d25, 0x23c9cf01, 0x95730a50), 1},
+    {{0xf2, 0x92, 0xe4, 0x68, 0x25, 0xf9, 0x22, 0x5a, 0xd2, 0x3d, 0xc0, 0x57, 0xc1, 0xd9, 0x1c, 0x4f, 0x57, 0xfc, 0xb1, 0x38, 0x6f, 0x29, 0xef, 0x10, 0x48, 0x1c, 0xb1, 0xd2, 0x25, 0x18, 0x59, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x11, 0xc9, 0x89}, SECP256K1_FE_CONST(0x3cea2c53, 0xb8b01701, 0x66ac7da6, 0x7194694a, 0xdacc84d5, 0x6389225e, 0x330134da, 0xb85a4d55), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x42, 0x18, 0xf2, 0x0a, 0xe6, 0xc6, 0x46, 0xb3, 0x63, 0xdb, 0x68, 0x60, 0x58, 0x22, 0xfb, 0x14, 0x26, 0x4c, 0xa8, 0xd2, 0x58, 0x7f, 0xdd, 0x6f, 0xbc, 0x75, 0x0d, 0x58, 0x7e, 0x76, 0xa7, 0xee}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x02, 0x8c, 0x59, 0x00, 0x63, 0xf6, 0x4d, 0x5a, 0x7f, 0x1c, 0x14, 0x91, 0x5c, 0xd6, 0x1e, 0xac, 0x88, 0x6a, 0xb2, 0x95, 0xbe, 0xbd, 0x91, 0x99, 0x25, 0x04, 0xcf, 0x77, 0xed, 0xb0, 0x28, 0xbd, 0xd6, 0x26, 0x7f}, SECP256K1_FE_CONST(0x3fde5713, 0xf8282eea, 0xd7d39d42, 0x01f44a7c, 0x85a5ac8a, 0x0681f35e, 0x54085c6b, 0x69543374), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x2c, 0x2c, 0x57, 0x09, 0xe7, 0x15, 0x6c, 0x41, 0x77, 0x17, 0xf2, 0xfe, 0xab, 0x14, 0x71, 0x41, 0xec, 0x3d, 0xa1, 0x9f, 0xb7, 0x59, 0x57, 0x5c, 0xc6, 0xe3, 0x7b, 0x2e, 0xa5, 0xac, 0x93, 0x09, 0xf2, 0x6f, 0x0f, 0x66}, SECP256K1_FE_CONST(0xd2469ab3, 0xe04acbb2, 0x1c65a180, 0x9f39caaf, 0xe7a77c13, 0xd10f9dd3, 0x8f391c01, 0xdc499c52), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3a, 0x08, 0xcc, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf7, 0x60, 0xe9, 0xf0}, SECP256K1_FE_CONST(0x38e2a5ce, 0x6a93e795, 0xe16d2c39, 0x8bc99f03, 0x69202ce2, 0x1e8f09d5, 0x6777b40f, 0xc512bccc), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3e, 0x91, 0x25, 0x7d, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x864b3dc9, 0x02c37670, 0x9c10a93a, 0xd4bbe29f, 0xce0012f3, 0xdc8672c6, 0x286bba28, 0xd7d6d6fc), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x79, 0x5d, 0x6c, 0x1c, 0x32, 0x2c, 0xad, 0xf5, 0x99, 0xdb, 0xb8, 0x64, 0x81, 0x52, 0x2b, 0x3c, 0xc5, 0x5f, 0x15, 0xa6, 0x79, 0x32, 0xdb, 0x2a, 0xfa, 0x01, 0x11, 0xd9, 0xed, 0x69, 0x81, 0xbc, 0xd1, 0x24, 0xbf, 0x44}, SECP256K1_FE_CONST(0x766dfe4a, 0x700d9bee, 0x288b903a, 0xd58870e3, 0xd4fe2f0e, 0xf780bcac, 0x5c823f32, 0x0d9a9bef), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8e, 0x42, 0x6f, 0x03, 0x92, 0x38, 0x90, 0x78, 0xc1, 0x2b, 0x1a, 0x89, 0xe9, 0x54, 0x2f, 0x05, 0x93, 0xbc, 0x96, 0xb6, 0xbf, 0xde, 0x82, 0x24, 0xf8, 0x65, 0x4e, 0xf5, 0xd5, 0xcd, 0xa9, 0x35, 0xa3, 0x58, 0x21, 0x94}, SECP256K1_FE_CONST(0xfaec7bc1, 0x987b6323, 0x3fbc5f95, 0x6edbf37d, 0x54404e74, 0x61c58ab8, 0x631bc68e, 0x451a0478), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x91, 0x19, 0x21, 0x39, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x45, 0xf0, 0xf1, 0xeb}, SECP256K1_FE_CONST(0xec29a50b, 0xae138dbf, 0x7d8e2482, 0x5006bb5f, 0xc1a2cc12, 0x43ba335b, 0xc6116fb9, 0xe498ec1f), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x98, 0xeb, 0x9a, 0xb7, 0x6e, 0x84, 0x49, 0x9c, 0x48, 0x3b, 0x3b, 0xf0, 0x62, 0x14, 0xab, 0xfe, 0x06, 0x5d, 0xdd, 0xf4, 0x3b, 0x86, 0x01, 0xde, 0x59, 0x6d, 0x63, 0xb9, 0xe4, 0x5a, 0x16, 0x6a, 0x58, 0x05, 0x41, 0xfe}, SECP256K1_FE_CONST(0x1e0ff2de, 0xe9b09b13, 0x6292a9e9, 0x10f0d6ac, 0x3e552a64, 0x4bba39e6, 0x4e9dd3e3, 0xbbd3d4d4), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x8b7dd5c3, 0xedba9ee9, 0x7b70eff4, 0x38f22dca, 0x9849c825, 0x4a2f3345, 0xa0a572ff, 0xeaae0928), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x0881950c, 0x8f51d6b9, 0xa6387465, 0xd5f12609, 0xef1bb254, 0x12a08a74, 0xcb2dfb20, 0x0c74bfbf), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa2, 0xf5, 0xcd, 0x83, 0x88, 0x16, 0xc1, 0x6c, 0x4f, 0xe8, 0xa1, 0x66, 0x1d, 0x60, 0x6f, 0xdb, 0x13, 0xcf, 0x9a, 0xf0, 0x4b, 0x97, 0x9a, 0x2e, 0x15, 0x9a, 0x09, 0x40, 0x9e, 0xbc, 0x86, 0x45, 0xd5, 0x8f, 0xde, 0x02}, SECP256K1_FE_CONST(0x2f083207, 0xb9fd9b55, 0x0063c31c, 0xd62b8746, 0xbd543bdc, 0x5bbf10e3, 0xa35563e9, 0x27f440c8), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x64, 0xd1, 0x62, 0x75, 0x05, 0x46, 0xce, 0x42, 0xb0, 0x43, 0x13, 0x61, 0xe5, 0x2d, 0x4f, 0x52, 0x42, 0xd8, 0xf2, 0x4f, 0x33, 0xe6, 0xb1, 0xf9, 0x9b, 0x59, 0x16, 0x47, 0xcb, 0xc8, 0x08, 0xf4, 0x62, 0xaf, 0x51}, SECP256K1_FE_CONST(0xd41244d1, 0x1ca4f652, 0x40687759, 0xf95ca9ef, 0xbab767ed, 0xedb38fd1, 0x8c36e18c, 0xd3b6f6a9), 1},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0xe5, 0xbe, 0x52, 0x37, 0x2d, 0xd6, 0xe8, 0x94, 0xb2, 0xa3, 0x26, 0xfc, 0x36, 0x05, 0xa6, 0xe8, 0xf3, 0xc6, 0x9c, 0x71, 0x0b, 0xf2, 0x7d, 0x63, 0x0d, 0xfe, 0x20, 0x04, 0x98, 0x8b, 0x78, 0xeb, 0x6e, 0xab, 0x36}, SECP256K1_FE_CONST(0x64bf84dd, 0x5e03670f, 0xdb24c0f5, 0xd3c2c365, 0x736f51db, 0x6c92d950, 0x10716ad2, 0xd36134c8), 0},
+    {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfb, 0xb9, 0x82, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf6, 0xd6, 0xdb, 0x1f}, SECP256K1_FE_CONST(0x1c92ccdf, 0xcf4ac550, 0xc28db57c, 0xff0c8515, 0xcb26936c, 0x786584a7, 0x0114008d, 0x6c33a34b), 0},
+};
+
+/* Set of expected ellswift_xdh BIP324 shared secrets, given private key, encodings, initiating,
+ * taken from the BIP324 test vectors. Created using an independent implementation, and tested
+ * against the paper authors' decoding code. */
+static const struct ellswift_xdh_test ellswift_xdh_tests_bip324[] = {
+    {{0x61, 0x06, 0x2e, 0xa5, 0x07, 0x1d, 0x80, 0x0b, 0xbf, 0xd5, 0x9e, 0x2e, 0x8b, 0x53, 0xd4, 0x7d, 0x19, 0x4b, 0x09, 0x5a, 0xe5, 0xa4, 0xdf, 0x04, 0x93, 0x6b, 0x49, 0x77, 0x2e, 0xf0, 0xd4, 0xd7}, {0xec, 0x0a, 0xdf, 0xf2, 0x57, 0xbb, 0xfe, 0x50, 0x0c, 0x18, 0x8c, 0x80, 0xb4, 0xfd, 0xd6, 0x40, 0xf6, 0xb4, 0x5a, 0x48, 0x2b, 0xbc, 0x15, 0xfc, 0x7c, 0xef, 0x59, 0x31, 0xde, 0xff, 0x0a, 0xa1, 0x86, 0xf6, 0xeb, 0x9b, 0xba, 0x7b, 0x85, 0xdc, 0x4d, 0xcc, 0x28, 0xb2, 0x87, 0x22, 0xde, 0x1e, 0x3d, 0x91, 0x08, 0xb9, 0x85, 0xe2, 0x96, 0x70, 0x45, 0x66, 0x8f, 0x66, 0x09, 0x8e, 0x47, 0x5b}, {0xa4, 0xa9, 0x4d, 0xfc, 0xe6, 0x9b, 0x4a, 0x2a, 0x0a, 0x09, 0x93, 0x13, 0xd1, 0x0f, 0x9f, 0x7e, 0x7d, 0x64, 0x9d, 0x60, 0x50, 0x1c, 0x9e, 0x1d, 0x27, 0x4c, 0x30, 0x0e, 0x0d, 0x89, 0xaa, 0xfa, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8f, 0xaf, 0x88, 0xd5}, 1, {0xc6, 0x99, 0x2a, 0x11, 0x7f, 0x5e, 0xdb, 0xea, 0x70, 0xc3, 0xf5, 0x11, 0xd3, 0x2d, 0x26, 0xb9, 0x79, 0x8b, 0xe4, 0xb8, 0x1a, 0x62, 0xea, 0xee, 0x1a, 0x5a, 0xca, 0xa8, 0x45, 0x9a, 0x35, 0x92}},
+    {{0x1f, 0x9c, 0x58, 0x1b, 0x35, 0x23, 0x18, 0x38, 0xf0, 0xf1, 0x7c, 0xf0, 0xc9, 0x79, 0x83, 0x5b, 0xac, 0xcb, 0x7f, 0x3a, 0xbb, 0xbb, 0x96, 0xff, 0xcc, 0x31, 0x8a, 0xb7, 0x1e, 0x6e, 0x12, 0x6f}, {0xa1, 0x85, 0x5e, 0x10, 0xe9, 0x4e, 0x00, 0xba, 0xa2, 0x30, 0x41, 0xd9, 0x16, 0xe2, 0x59, 0xf7, 0x04, 0x4e, 0x49, 0x1d, 0xa6, 0x17, 0x12, 0x69, 0x69, 0x47, 0x63, 0xf0, 0x18, 0xc7, 0xe6, 0x36, 0x93, 0xd2, 0x95, 0x75, 0xdc, 0xb4, 0x64, 0xac, 0x81, 0x6b, 0xaa, 0x1b, 0xe3, 0x53, 0xba, 0x12, 0xe3, 0x87, 0x6c, 0xba, 0x76, 0x28, 0xbd, 0x0b, 0xd8, 0xe7, 0x55, 0xe7, 0x21, 0xeb, 0x01, 0x40}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, 0, {0xa0, 0x13, 0x8f, 0x56, 0x4f, 0x74, 0xd0, 0xad, 0x70, 0xbc, 0x33, 0x7d, 0xac, 0xc9, 0xd0, 0xbf, 0x1d, 0x23, 0x49, 0x36, 0x4c, 0xaf, 0x11, 0x88, 0xa1, 0xe6, 0xe8, 0xdd, 0xb3, 0xb7, 0xb1, 0x84}},
+    {{0x02, 0x86, 0xc4, 0x1c, 0xd3, 0x09, 0x13, 0xdb, 0x0f, 0xdf, 0xf7, 0xa6, 0x4e, 0xbd, 0xa5, 0xc8, 0xe3, 0xe7, 0xce, 0xf1, 0x0f, 0x2a, 0xeb, 0xc0, 0x0a, 0x76, 0x50, 0x44, 0x3c, 0xf4, 0xc6, 0x0d}, {0xd1, 0xee, 0x8a, 0x93, 0xa0, 0x11, 0x30, 0xcb, 0xf2, 0x99, 0x24, 0x9a, 0x25, 0x8f, 0x94, 0xfe, 0xb5, 0xf4, 0x69, 0xe7, 0xd0, 0xf2, 0xf2, 0x8f, 0x69, 0xee, 0x5e, 0x9a, 0xa8, 0xf9, 0xb5, 0x4a, 0x60, 0xf2, 0xc3, 0xff, 0x2d, 0x02, 0x36, 0x34, 0xec, 0x7f, 0x41, 0x27, 0xa9, 0x6c, 0xc1, 0x16, 0x62, 0xe4, 0x02, 0x89, 0x4c, 0xf1, 0xf6, 0x94, 0xfb, 0x9a, 0x7e, 0xaa, 0x5f, 0x1d, 0x92, 0x44}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x22, 0xd5, 0xe4, 0x41, 0x52, 0x4d, 0x57, 0x1a, 0x52, 0xb3, 0xde, 0xf1, 0x26, 0x18, 0x9d, 0x3f, 0x41, 0x68, 0x90, 0xa9, 0x9d, 0x4d, 0xa6, 0xed, 0xe2, 0xb0, 0xcd, 0xe1, 0x76, 0x0c, 0xe2, 0xc3, 0xf9, 0x84, 0x57, 0xae}, 1, {0x25, 0x0b, 0x93, 0x57, 0x0d, 0x41, 0x11, 0x49, 0x10, 0x5a, 0xb8, 0xcb, 0x0b, 0xc5, 0x07, 0x99, 0x14, 0x90, 0x63, 0x06, 0x36, 0x8c, 0x23, 0xe9, 0xd7, 0x7c, 0x2a, 0x33, 0x26, 0x5b, 0x99, 0x4c}},
+    {{0x6c, 0x77, 0x43, 0x2d, 0x1f, 0xda, 0x31, 0xe9, 0xf9, 0x42, 0xf8, 0xaf, 0x44, 0x60, 0x7e, 0x10, 0xf3, 0xad, 0x38, 0xa6, 0x5f, 0x8a, 0x4b, 0xdd, 0xae, 0x82, 0x3e, 0x5e, 0xff, 0x90, 0xdc, 0x38}, {0xd2, 0x68, 0x50, 0x70, 0xc1, 0xe6, 0x37, 0x6e, 0x63, 0x3e, 0x82, 0x52, 0x96, 0x63, 0x4f, 0xd4, 0x61, 0xfa, 0x9e, 0x5b, 0xdf, 0x21, 0x09, 0xbc, 0xeb, 0xd7, 0x35, 0xe5, 0xa9, 0x1f, 0x3e, 0x58, 0x7c, 0x5c, 0xb7, 0x82, 0xab, 0xb7, 0x97, 0xfb, 0xf6, 0xbb, 0x50, 0x74, 0xfd, 0x15, 0x42, 0xa4, 0x74, 0xf2, 0xa4, 0x5b, 0x67, 0x37, 0x63, 0xec, 0x2d, 0xb7, 0xfb, 0x99, 0xb7, 0x37, 0xbb, 0xb9}, {0x56, 0xbd, 0x0c, 0x06, 0xf1, 0x03, 0x52, 0xc3, 0xa1, 0xa9, 0xf4, 0xb4, 0xc9, 0x2f, 0x6f, 0xa2, 0xb2, 0x6d, 0xf1, 0x24, 0xb5, 0x78, 0x78, 0x35, 0x3c, 0x1f, 0xc6, 0x91, 0xc5, 0x1a, 0xbe, 0xa7, 0x7c, 0x88, 0x17, 0xda, 0xee, 0xb9, 0xfa, 0x54, 0x6b, 0x77, 0xc8, 0xda, 0xf7, 0x9d, 0x89, 0xb2, 0x2b, 0x0e, 0x1b, 0x87, 0x57, 0x4e, 0xce, 0x42, 0x37, 0x1f, 0x00, 0x23, 0x7a, 0xa9, 0xd8, 0x3a}, 0, {0x19, 0x18, 0xb7, 0x41, 0xef, 0x5f, 0x9d, 0x1d, 0x76, 0x70, 0xb0, 0x50, 0xc1, 0x52, 0xb4, 0xa4, 0xea, 0xd2, 0xc3, 0x1b, 0xe9, 0xae, 0xcb, 0x06, 0x81, 0xc0, 0xcd, 0x43, 0x24, 0x15, 0x08, 0x53}},
+    {{0xa6, 0xec, 0x25, 0x12, 0x7c, 0xa1, 0xaa, 0x4c, 0xf1, 0x6b, 0x20, 0x08, 0x4b, 0xa1, 0xe6, 0x51, 0x6b, 0xaa, 0xe4, 0xd3, 0x24, 0x22, 0x28, 0x8e, 0x9b, 0x36, 0xd8, 0xbd, 0xdd, 0x2d, 0xe3, 0x5a}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x05, 0x3d, 0x7e, 0xcc, 0xa5, 0x3e, 0x33, 0xe1, 0x85, 0xa8, 0xb9, 0xbe, 0x4e, 0x76, 0x99, 0xa9, 0x7c, 0x6f, 0xf4, 0xc7, 0x95, 0x52, 0x2e, 0x59, 0x18, 0xab, 0x7c, 0xd6, 0xb6, 0x88, 0x4f, 0x67, 0xe6, 0x83, 0xf3, 0xdc}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa7, 0x73, 0x0b, 0xe3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, 1, {0xdd, 0x21, 0x0a, 0xa6, 0x62, 0x9f, 0x20, 0xbb, 0x32, 0x8e, 0x5d, 0x89, 0xda, 0xa6, 0xeb, 0x2a, 0xc3, 0xd1, 0xc6, 0x58, 0xa7, 0x25, 0x53, 0x6f, 0xf1, 0x54, 0xf3, 0x1b, 0x53, 0x6c, 0x23, 0xb2}},
+    {{0x0a, 0xf9, 0x52, 0x65, 0x9e, 0xd7, 0x6f, 0x80, 0xf5, 0x85, 0x96, 0x6b, 0x95, 0xab, 0x6e, 0x6f, 0xd6, 0x86, 0x54, 0x67, 0x28, 0x27, 0x87, 0x86, 0x84, 0xc8, 0xb5, 0x47, 0xb1, 0xb9, 0x4f, 0x5a}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc8, 0x10, 0x17, 0xfd, 0x92, 0xfd, 0x31, 0x63, 0x7c, 0x26, 0xc9, 0x06, 0xb4, 0x20, 0x92, 0xe1, 0x1c, 0xc0, 0xd3, 0xaf, 0xae, 0x8d, 0x90, 0x19, 0xd2, 0x57, 0x8a, 0xf2, 0x27, 0x35, 0xce, 0x7b, 0xc4, 0x69, 0xc7, 0x2d}, {0x96, 0x52, 0xd7, 0x8b, 0xae, 0xfc, 0x02, 0x8c, 0xd3, 0x7a, 0x6a, 0x92, 0x62, 0x5b, 0x8b, 0x8f, 0x85, 0xfd, 0xe1, 0xe4, 0xc9, 0x44, 0xad, 0x3f, 0x20, 0xe1, 0x98, 0xbe, 0xf8, 0xc0, 0x2f, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf2, 0xe9, 0x18, 0x70}, 0, {0x35, 0x68, 0xf2, 0xae, 0xa2, 0xe1, 0x4e, 0xf4, 0xee, 0x4a, 0x3c, 0x2a, 0x8b, 0x8d, 0x31, 0xbc, 0x5e, 0x31, 0x87, 0xba, 0x86, 0xdb, 0x10, 0x73, 0x9b, 0x4f, 0xf8, 0xec, 0x92, 0xff, 0x66, 0x55}},
+    {{0xf9, 0x0e, 0x08, 0x0c, 0x64, 0xb0, 0x58, 0x24, 0xc5, 0xa2, 0x4b, 0x25, 0x01, 0xd5, 0xae, 0xaf, 0x08, 0xaf, 0x38, 0x72, 0xee, 0x86, 0x0a, 0xa8, 0x0b, 0xdc, 0xd4, 0x30, 0xf7, 0xb6, 0x34, 0x94}, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x11, 0x51, 0x73, 0x76, 0x5d, 0xc2, 0x02, 0xcf, 0x02, 0x9a, 0xd3, 0xf1, 0x54, 0x79, 0x73, 0x5d, 0x57, 0x69, 0x7a, 0xf1, 0x2b, 0x01, 0x31, 0xdd, 0x21, 0x43, 0x0d, 0x57, 0x72, 0xe4, 0xef, 0x11, 0x47, 0x4d, 0x58, 0xb9}, {0x12, 0xa5, 0x0f, 0x3f, 0xaf, 0xea, 0x7c, 0x1e, 0xea, 0xda, 0x4c, 0xf8, 0xd3, 0x37, 0x77, 0x70, 0x4b, 0x77, 0x36, 0x14, 0x53, 0xaf, 0xc8, 0x3b, 0xda, 0x91, 0xee, 0xf3, 0x49, 0xae, 0x04, 0x4d, 0x20, 0x12, 0x6c, 0x62, 0x00, 0x54, 0x7e, 0xa5, 0xa6, 0x91, 0x17, 0x76, 0xc0, 0x5d, 0xee, 0x2a, 0x7f, 0x1a, 0x9b, 0xa7, 0xdf, 0xba, 0xbb, 0xbd, 0x27, 0x3c, 0x3e, 0xf2, 0x9e, 0xf4, 0x6e, 0x46}, 1, {0xe2, 0x54, 0x61, 0xfb, 0x0e, 0x4c, 0x16, 0x2e, 0x18, 0x12, 0x3e, 0xcd, 0xe8, 0x83, 0x42, 0xd5, 0x4d, 0x44, 0x96, 0x31, 0xe9, 0xb7, 0x5a, 0x26, 0x6f, 0xd9, 0x26, 0x0c, 0x2b, 0xb2, 0xf4, 0x1d}},
+};
+
+/** This is a hasher for ellswift_xdh which just returns the shared X coordinate.
+ *
+ * This is generally a bad idea as it means changes to the encoding of the
+ * exchanged public keys do not affect the shared secret. However, it's used here
+ * in tests to be able to verify the X coordinate through other means.
+ */
+static int ellswift_xdh_hash_x32(unsigned char *output, const unsigned char *x32, const unsigned char *ell_a64, const unsigned char *ell_b64, void *data) {
+    (void)ell_a64;
+    (void)ell_b64;
+    (void)data;
+    memcpy(output, x32, 32);
+    return 1;
+}
+
+void run_ellswift_tests(void) {
+    int i = 0;
+    /* Test vectors. */
+    for (i = 0; (unsigned)i < sizeof(ellswift_xswiftec_inv_tests) / sizeof(ellswift_xswiftec_inv_tests[0]); ++i) {
+        const struct ellswift_xswiftec_inv_test *testcase = &ellswift_xswiftec_inv_tests[i];
+        int c;
+        for (c = 0; c < 8; ++c) {
+            secp256k1_fe t;
+            int ret = secp256k1_ellswift_xswiftec_inv_var(&t, &testcase->x, &testcase->u, c);
+            CHECK(ret == ((testcase->enc_bitmap >> c) & 1));
+            if (ret) {
+                secp256k1_fe x2;
+                CHECK(check_fe_equal(&t, &testcase->encs[c]));
+                secp256k1_ellswift_xswiftec_var(&x2, &testcase->u, &testcase->encs[c]);
+                CHECK(check_fe_equal(&testcase->x, &x2));
+            }
+        }
+    }
+    for (i = 0; (unsigned)i < sizeof(ellswift_decode_tests) / sizeof(ellswift_decode_tests[0]); ++i) {
+        const struct ellswift_decode_test *testcase = &ellswift_decode_tests[i];
+        secp256k1_pubkey pubkey;
+        secp256k1_ge ge;
+        int ret;
+        ret = secp256k1_ellswift_decode(CTX, &pubkey, testcase->enc);
+        CHECK(ret);
+        ret = secp256k1_pubkey_load(CTX, &ge, &pubkey);
+        CHECK(ret);
+        CHECK(check_fe_equal(&testcase->x, &ge.x));
+        CHECK(secp256k1_fe_is_odd(&ge.y) == testcase->odd_y);
+    }
+    for (i = 0; (unsigned)i < sizeof(ellswift_xdh_tests_bip324) / sizeof(ellswift_xdh_tests_bip324[0]); ++i) {
+        const struct ellswift_xdh_test *test = &ellswift_xdh_tests_bip324[i];
+        unsigned char shared_secret[32];
+        int ret;
+        int party = !test->initiating;
+        const unsigned char* ell_a64 = party ? test->ellswift_theirs : test->ellswift_ours;
+        const unsigned char* ell_b64 = party ? test->ellswift_ours   : test->ellswift_theirs;
+        ret = secp256k1_ellswift_xdh(CTX, shared_secret,
+                                     ell_a64, ell_b64,
+                                     test->priv_ours,
+                                     party,
+                                     secp256k1_ellswift_xdh_hash_function_bip324,
+                                     NULL);
+        CHECK(ret);
+        CHECK(secp256k1_memcmp_var(shared_secret, test->shared_secret, 32) == 0);
+    }
+    /* Verify that secp256k1_ellswift_encode + decode roundtrips. */
+    for (i = 0; i < 1000 * COUNT; i++) {
+        unsigned char rnd32[32];
+        unsigned char ell64[64];
+        secp256k1_ge g, g2;
+        secp256k1_pubkey pubkey, pubkey2;
+        /* Generate random public key and random randomizer. */
+        random_group_element_test(&g);
+        secp256k1_pubkey_save(&pubkey, &g);
+        secp256k1_testrand256(rnd32);
+        /* Convert the public key to ElligatorSwift and back. */
+        secp256k1_ellswift_encode(CTX, ell64, &pubkey, rnd32);
+        secp256k1_ellswift_decode(CTX, &pubkey2, ell64);
+        secp256k1_pubkey_load(CTX, &g2, &pubkey2);
+        /* Compare with original. */
+        CHECK(secp256k1_ge_eq_var(&g, &g2));
+    }
+    /* Verify the behavior of secp256k1_ellswift_create */
+    for (i = 0; i < 400 * COUNT; i++) {
+        unsigned char auxrnd32[32], sec32[32];
+        secp256k1_scalar sec;
+        secp256k1_gej res;
+        secp256k1_ge dec;
+        secp256k1_pubkey pub;
+        unsigned char ell64[64];
+        int ret;
+        /* Generate random secret key and random randomizer. */
+        if (i & 1) secp256k1_testrand256_test(auxrnd32);
+        random_scalar_order_test(&sec);
+        secp256k1_scalar_get_b32(sec32, &sec);
+        /* Construct ElligatorSwift-encoded public keys for that key. */
+        ret = secp256k1_ellswift_create(CTX, ell64, sec32, (i & 1) ? auxrnd32 : NULL);
+        CHECK(ret);
+        /* Decode it, and compare with traditionally-computed public key. */
+        secp256k1_ellswift_decode(CTX, &pub, ell64);
+        secp256k1_pubkey_load(CTX, &dec, &pub);
+        secp256k1_ecmult(&res, NULL, &secp256k1_scalar_zero, &sec);
+        CHECK(secp256k1_gej_eq_ge_var(&res, &dec));
+    }
+    /* Verify that secp256k1_ellswift_xdh computes the right shared X coordinate. */
+    for (i = 0; i < 800 * COUNT; i++) {
+        unsigned char ell64[64], sec32[32], share32[32];
+        secp256k1_scalar sec;
+        secp256k1_ge dec, res;
+        secp256k1_fe share_x;
+        secp256k1_gej decj, resj;
+        secp256k1_pubkey pub;
+        int ret;
+        /* Generate random secret key. */
+        random_scalar_order_test(&sec);
+        secp256k1_scalar_get_b32(sec32, &sec);
+        /* Generate random ElligatorSwift encoding for the remote key and decode it. */
+        secp256k1_testrand256_test(ell64);
+        secp256k1_testrand256_test(ell64 + 32);
+        secp256k1_ellswift_decode(CTX, &pub, ell64);
+        secp256k1_pubkey_load(CTX, &dec, &pub);
+        secp256k1_gej_set_ge(&decj, &dec);
+        /* Compute the X coordinate of seckey*pubkey using ellswift_xdh. Note that we
+         * pass ell64 as claimed (but incorrect) encoding for sec32 here; this works
+         * because the "hasher" function we use here ignores the ell64 arguments. */
+        ret = secp256k1_ellswift_xdh(CTX, share32, ell64, ell64, sec32, i & 1, &ellswift_xdh_hash_x32, NULL);
+        CHECK(ret);
+        (void)secp256k1_fe_set_b32_limit(&share_x, share32); /* no overflow is possible */
+        SECP256K1_FE_VERIFY(&share_x);
+        /* Compute seckey*pubkey directly. */
+        secp256k1_ecmult(&resj, &decj, &sec, NULL);
+        secp256k1_ge_set_gej(&res, &resj);
+        /* Compare. */
+        CHECK(check_fe_equal(&res.x, &share_x));
+    }
+    /* Verify the joint behavior of secp256k1_ellswift_xdh */
+    for (i = 0; i < 200 * COUNT; i++) {
+        unsigned char auxrnd32a[32], auxrnd32b[32], auxrnd32a_bad[32], auxrnd32b_bad[32];
+        unsigned char sec32a[32], sec32b[32], sec32a_bad[32], sec32b_bad[32];
+        secp256k1_scalar seca, secb;
+        unsigned char ell64a[64], ell64b[64], ell64a_bad[64], ell64b_bad[64];
+        unsigned char share32a[32], share32b[32], share32_bad[32];
+        unsigned char prefix64[64];
+        secp256k1_ellswift_xdh_hash_function hash_function;
+        void* data;
+        int ret;
+
+        /* Pick hasher to use. */
+        if ((i % 3) == 0) {
+            hash_function = ellswift_xdh_hash_x32;
+            data = NULL;
+        } else if ((i % 3) == 1) {
+            hash_function = secp256k1_ellswift_xdh_hash_function_bip324;
+            data = NULL;
+        } else {
+            hash_function = secp256k1_ellswift_xdh_hash_function_prefix;
+            secp256k1_testrand256_test(prefix64);
+            secp256k1_testrand256_test(prefix64 + 32);
+            data = prefix64;
+        }
+
+        /* Generate random secret keys and random randomizers. */
+        secp256k1_testrand256_test(auxrnd32a);
+        secp256k1_testrand256_test(auxrnd32b);
+        random_scalar_order_test(&seca);
+        /* Draw secb uniformly at random to make sure that the secret keys
+         * differ */
+        random_scalar_order(&secb);
+        secp256k1_scalar_get_b32(sec32a, &seca);
+        secp256k1_scalar_get_b32(sec32b, &secb);
+
+        /* Construct ElligatorSwift-encoded public keys for those keys. */
+        /* For A: */
+        ret = secp256k1_ellswift_create(CTX, ell64a, sec32a, auxrnd32a);
+        CHECK(ret);
+        /* For B: */
+        ret = secp256k1_ellswift_create(CTX, ell64b, sec32b, auxrnd32b);
+        CHECK(ret);
+
+        /* Compute the shared secret both ways and compare with each other. */
+        /* For A: */
+        ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32a, 0, hash_function, data);
+        CHECK(ret);
+        /* For B: */
+        ret = secp256k1_ellswift_xdh(CTX, share32b, ell64a, ell64b, sec32b, 1, hash_function, data);
+        CHECK(ret);
+        /* And compare: */
+        CHECK(secp256k1_memcmp_var(share32a, share32b, 32) == 0);
+
+        /* Verify that the shared secret doesn't match if other side's public key is incorrect. */
+        /* For A (using a bad public key for B): */
+        memcpy(ell64b_bad, ell64b, sizeof(ell64a_bad));
+        secp256k1_testrand_flip(ell64b_bad, sizeof(ell64b_bad));
+        ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, hash_function, data);
+        CHECK(ret); /* Mismatching encodings don't get detected by secp256k1_ellswift_xdh. */
+        CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0);
+        /* For B (using a bad public key for A): */
+        memcpy(ell64a_bad, ell64a, sizeof(ell64a_bad));
+        secp256k1_testrand_flip(ell64a_bad, sizeof(ell64a_bad));
+        ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, hash_function, data);
+        CHECK(ret);
+        CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0);
+
+        /* Verify that the shared secret doesn't match if the private key is incorrect. */
+        /* For A: */
+        memcpy(sec32a_bad, sec32a, sizeof(sec32a_bad));
+        secp256k1_testrand_flip(sec32a_bad, sizeof(sec32a_bad));
+        ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a_bad, 0, hash_function, data);
+        CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32a, 32) != 0);
+        /* For B: */
+        memcpy(sec32b_bad, sec32b, sizeof(sec32b_bad));
+        secp256k1_testrand_flip(sec32b_bad, sizeof(sec32b_bad));
+        ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b_bad, 1, hash_function, data);
+        CHECK(!ret || secp256k1_memcmp_var(share32_bad, share32b, 32) != 0);
+
+        if (hash_function != ellswift_xdh_hash_x32) {
+            /* Verify that the shared secret doesn't match when a different encoding of the same public key is used. */
+            /* For A (changing B's public key): */
+            memcpy(auxrnd32b_bad, auxrnd32b, sizeof(auxrnd32b_bad));
+            secp256k1_testrand_flip(auxrnd32b_bad, sizeof(auxrnd32b_bad));
+            ret = secp256k1_ellswift_create(CTX, ell64b_bad, sec32b, auxrnd32b_bad);
+            CHECK(ret);
+            ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b_bad, sec32a, 0, hash_function, data);
+            CHECK(ret);
+            CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0);
+            /* For B (changing A's public key): */
+            memcpy(auxrnd32a_bad, auxrnd32a, sizeof(auxrnd32a_bad));
+            secp256k1_testrand_flip(auxrnd32a_bad, sizeof(auxrnd32a_bad));
+            ret = secp256k1_ellswift_create(CTX, ell64a_bad, sec32a, auxrnd32a_bad);
+            CHECK(ret);
+            ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a_bad, ell64b, sec32b, 1, hash_function, data);
+            CHECK(ret);
+            CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0);
+
+            /* Verify that swapping sides changes the shared secret. */
+            /* For A (claiming to be B): */
+            ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32a, 1, hash_function, data);
+            CHECK(ret);
+            CHECK(secp256k1_memcmp_var(share32_bad, share32a, 32) != 0);
+            /* For B (claiming to be A): */
+            ret = secp256k1_ellswift_xdh(CTX, share32_bad, ell64a, ell64b, sec32b, 0, hash_function, data);
+            CHECK(ret);
+            CHECK(secp256k1_memcmp_var(share32_bad, share32b, 32) != 0);
+        }
+    }
+
+    /* Test hash initializers. */
+    {
+        secp256k1_sha256 sha, sha_optimized;
+        static const unsigned char encode_tag[25] = "secp256k1_ellswift_encode";
+        static const unsigned char create_tag[25] = "secp256k1_ellswift_create";
+        static const unsigned char bip324_tag[26] = "bip324_ellswift_xonly_ecdh";
+
+        /* Check that hash initialized by
+         * secp256k1_ellswift_sha256_init_encode has the expected
+         * state. */
+        secp256k1_sha256_initialize_tagged(&sha, encode_tag, sizeof(encode_tag));
+        secp256k1_ellswift_sha256_init_encode(&sha_optimized);
+        test_sha256_eq(&sha, &sha_optimized);
+
+        /* Check that hash initialized by
+         * secp256k1_ellswift_sha256_init_create has the expected
+         * state. */
+        secp256k1_sha256_initialize_tagged(&sha, create_tag, sizeof(create_tag));
+        secp256k1_ellswift_sha256_init_create(&sha_optimized);
+        test_sha256_eq(&sha, &sha_optimized);
+
+        /* Check that hash initialized by
+         * secp256k1_ellswift_sha256_init_bip324 has the expected
+         * state. */
+        secp256k1_sha256_initialize_tagged(&sha, bip324_tag, sizeof(bip324_tag));
+        secp256k1_ellswift_sha256_init_bip324(&sha_optimized);
+        test_sha256_eq(&sha, &sha_optimized);
+    }
+}
+
+#endif

src/modules/extrakeys/main_impl.h

@@ -9,6 +9,7 @@
 
 #include "../../../include/secp256k1.h"
 #include "../../../include/secp256k1_extrakeys.h"
+#include "../../util.h"
 
 static SECP256K1_INLINE int secp256k1_xonly_pubkey_load(const secp256k1_context* ctx, secp256k1_ge *ge, const secp256k1_xonly_pubkey *pubkey) {
     return secp256k1_pubkey_load(ctx, ge, (const secp256k1_pubkey *) pubkey);
@@ -27,7 +28,7 @@ int secp256k1_xonly_pubkey_parse(const secp256k1_context* ctx, secp256k1_xonly_p
     memset(pubkey, 0, sizeof(*pubkey));
     ARG_CHECK(input32 != NULL);
 
-    if (!secp256k1_fe_set_b32(&x, input32)) {
+    if (!secp256k1_fe_set_b32_limit(&x, input32)) {
         return 0;
     }
     if (!secp256k1_ge_set_xo_var(&pk, &x, 0)) {

src/modules/extrakeys/tests_exhaustive_impl.h

@@ -47,8 +47,8 @@ static void test_exhaustive_extrakeys(const secp256k1_context *ctx, const secp25
         CHECK(secp256k1_memcmp_var(xonly_pubkey_bytes[i - 1], buf, 32) == 0);
 
         /* Compare the xonly_pubkey bytes against the precomputed group. */
-        secp256k1_fe_set_b32(&fe, xonly_pubkey_bytes[i - 1]);
-        CHECK(secp256k1_fe_equal_var(&fe, &group[i].x));
+        secp256k1_fe_set_b32_mod(&fe, xonly_pubkey_bytes[i - 1]);
+        CHECK(secp256k1_fe_equal(&fe, &group[i].x));
 
         /* Check the parity against the precomputed group. */
         fe = group[i].y;

src/modules/extrakeys/tests_impl.h

@@ -9,12 +9,7 @@
 
 #include "../../../include/secp256k1_extrakeys.h"
 
-static void set_counting_callbacks(secp256k1_context *ctx0, int *ecount) {
-    secp256k1_context_set_error_callback(ctx0, counting_illegal_callback_fn, ecount);
-    secp256k1_context_set_illegal_callback(ctx0, counting_illegal_callback_fn, ecount);
-}
-
-void test_xonly_pubkey(void) {
+static void test_xonly_pubkey(void) {
     secp256k1_pubkey pk;
     secp256k1_xonly_pubkey xonly_pk, xonly_pk_tmp;
     secp256k1_ge pk1;
@@ -28,107 +23,91 @@ void test_xonly_pubkey(void) {
     int pk_parity;
     int i;
 
-    int ecount;
-
-    set_counting_callbacks(ctx, &ecount);
-
     secp256k1_testrand256(sk);
     memset(ones32, 0xFF, 32);
     secp256k1_testrand256(xy_sk);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk) == 1);
 
     /* Test xonly_pubkey_from_pubkey */
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, NULL, &pk_parity, &pk) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_from_pubkey(CTX, NULL, &pk_parity, &pk));
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, NULL, &pk) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, NULL));
     memset(&pk, 0, sizeof(pk));
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 0);
-    CHECK(ecount == 3);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk));
 
     /* Choose a secret key such that the resulting pubkey and xonly_pubkey match. */
     memset(sk, 0, sizeof(sk));
     sk[0] = 1;
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk) == 1);
     CHECK(secp256k1_memcmp_var(&pk, &xonly_pk, sizeof(pk)) == 0);
     CHECK(pk_parity == 0);
 
     /* Choose a secret key such that pubkey and xonly_pubkey are each others
      * negation. */
     sk[0] = 2;
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk) == 1);
     CHECK(secp256k1_memcmp_var(&xonly_pk, &pk, sizeof(xonly_pk)) != 0);
     CHECK(pk_parity == 1);
-    secp256k1_pubkey_load(ctx, &pk1, &pk);
-    secp256k1_pubkey_load(ctx, &pk2, (secp256k1_pubkey *) &xonly_pk);
+    secp256k1_pubkey_load(CTX, &pk1, &pk);
+    secp256k1_pubkey_load(CTX, &pk2, (secp256k1_pubkey *) &xonly_pk);
     CHECK(secp256k1_fe_equal(&pk1.x, &pk2.x) == 1);
     secp256k1_fe_negate(&y, &pk2.y, 1);
     CHECK(secp256k1_fe_equal(&pk1.y, &y) == 1);
 
     /* Test xonly_pubkey_serialize and xonly_pubkey_parse */
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, NULL, &xonly_pk) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, NULL) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_serialize(CTX, NULL, &xonly_pk));
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_serialize(CTX, buf32, NULL));
     CHECK(secp256k1_memcmp_var(buf32, zeros64, 32) == 0);
-    CHECK(ecount == 2);
     {
         /* A pubkey filled with 0s will fail to serialize due to pubkey_load
          * special casing. */
         secp256k1_xonly_pubkey pk_tmp;
         memset(&pk_tmp, 0, sizeof(pk_tmp));
-        CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &pk_tmp) == 0);
+        /* pubkey_load calls illegal callback */
+        CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_serialize(CTX, buf32, &pk_tmp));
     }
-    /* pubkey_load called illegal callback */
-    CHECK(ecount == 3);
 
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &xonly_pk) == 1);
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, NULL, buf32) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, buf32, &xonly_pk) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_parse(CTX, NULL, buf32));
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_parse(CTX, &xonly_pk, NULL));
 
     /* Serialization and parse roundtrip */
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &xonly_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk_tmp, buf32) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, NULL, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, buf32, &xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &xonly_pk_tmp, buf32) == 1);
     CHECK(secp256k1_memcmp_var(&xonly_pk, &xonly_pk_tmp, sizeof(xonly_pk)) == 0);
 
     /* Test parsing invalid field elements */
     memset(&xonly_pk, 1, sizeof(xonly_pk));
     /* Overflowing field element */
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, ones32) == 0);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &xonly_pk, ones32) == 0);
     CHECK(secp256k1_memcmp_var(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
     memset(&xonly_pk, 1, sizeof(xonly_pk));
     /* There's no point with x-coordinate 0 on secp256k1 */
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, zeros64) == 0);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &xonly_pk, zeros64) == 0);
     CHECK(secp256k1_memcmp_var(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
     /* If a random 32-byte string can not be parsed with ec_pubkey_parse
      * (because interpreted as X coordinate it does not correspond to a point on
      * the curve) then xonly_pubkey_parse should fail as well. */
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         unsigned char rand33[33];
         secp256k1_testrand256(&rand33[1]);
         rand33[0] = SECP256K1_TAG_PUBKEY_EVEN;
-        if (!secp256k1_ec_pubkey_parse(ctx, &pk, rand33, 33)) {
+        if (!secp256k1_ec_pubkey_parse(CTX, &pk, rand33, 33)) {
             memset(&xonly_pk, 1, sizeof(xonly_pk));
-            CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, &rand33[1]) == 0);
+            CHECK(secp256k1_xonly_pubkey_parse(CTX, &xonly_pk, &rand33[1]) == 0);
             CHECK(secp256k1_memcmp_var(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
         } else {
-            CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, &rand33[1]) == 1);
+            CHECK(secp256k1_xonly_pubkey_parse(CTX, &xonly_pk, &rand33[1]) == 1);
         }
     }
-    CHECK(ecount == 2);
 }
 
-void test_xonly_pubkey_comparison(void) {
+static void test_xonly_pubkey_comparison(void) {
     unsigned char pk1_ser[32] = {
         0x58, 0x84, 0xb3, 0xa2, 0x4b, 0x97, 0x37, 0x88, 0x92, 0x38, 0xa6, 0x26, 0x62, 0x52, 0x35, 0x11,
         0xd0, 0x9a, 0xa1, 0x1b, 0x80, 0x0b, 0x5e, 0x93, 0x80, 0x26, 0x11, 0xef, 0x67, 0x4b, 0xd9, 0x23
@@ -139,32 +118,29 @@ void test_xonly_pubkey_comparison(void) {
     };
     secp256k1_xonly_pubkey pk1;
     secp256k1_xonly_pubkey pk2;
-    int ecount = 0;
 
-    set_counting_callbacks(ctx, &ecount);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &pk1, pk1_ser) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &pk2, pk2_ser) == 1);
 
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk1, pk1_ser) == 1);
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk2, pk2_ser) == 1);
-
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, NULL, &pk2) < 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk1, NULL) > 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk1, &pk2) < 0);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk2, &pk1) > 0);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk1, &pk1) == 0);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk2, &pk2) == 0);
-    CHECK(ecount == 2);
+    CHECK_ILLEGAL_VOID(CTX, CHECK(secp256k1_xonly_pubkey_cmp(CTX, NULL, &pk2) < 0));
+    CHECK_ILLEGAL_VOID(CTX, CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk1, NULL) > 0));
+    CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk1, &pk2) < 0);
+    CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk2, &pk1) > 0);
+    CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk1, &pk1) == 0);
+    CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk2, &pk2) == 0);
     memset(&pk1, 0, sizeof(pk1)); /* illegal pubkey */
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk1, &pk2) < 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk1, &pk1) == 0);
-    CHECK(ecount == 5);
-    CHECK(secp256k1_xonly_pubkey_cmp(ctx, &pk2, &pk1) > 0);
-    CHECK(ecount == 6);
+    CHECK_ILLEGAL_VOID(CTX, CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk1, &pk2) < 0));
+    {
+        int32_t ecount = 0;
+        secp256k1_context_set_illegal_callback(CTX, counting_callback_fn, &ecount);
+        CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk1, &pk1) == 0);
+        CHECK(ecount == 2);
+        secp256k1_context_set_illegal_callback(CTX, NULL, NULL);
+    }
+    CHECK_ILLEGAL_VOID(CTX, CHECK(secp256k1_xonly_pubkey_cmp(CTX, &pk2, &pk1) > 0));
 }
 
-void test_xonly_pubkey_tweak(void) {
+static void test_xonly_pubkey_tweak(void) {
     unsigned char zeros64[64] = { 0 };
     unsigned char overflows[32];
     unsigned char sk[32];
@@ -175,63 +151,51 @@ void test_xonly_pubkey_tweak(void) {
     unsigned char tweak[32];
     int i;
 
-    int ecount;
-
-    set_counting_callbacks(ctx, &ecount);
-
     memset(overflows, 0xff, sizeof(overflows));
     secp256k1_testrand256(tweak);
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &internal_pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &internal_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
 
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, NULL, &internal_xonly_pk, tweak) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, NULL, tweak) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add(CTX, NULL, &internal_xonly_pk, tweak));
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, NULL, tweak));
     /* NULL internal_xonly_pk zeroes the output_pk */
     CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk)) == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, NULL) == 0);
-    CHECK(ecount == 3);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, NULL));
     /* NULL tweak zeroes the output_pk */
     CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk)) == 0);
 
     /* Invalid tweak zeroes the output_pk */
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, overflows) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, overflows) == 0);
     CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk))  == 0);
 
     /* A zero tweak is fine */
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, zeros64) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, zeros64) == 1);
 
     /* Fails if the resulting key was infinity */
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         secp256k1_scalar scalar_tweak;
         /* Because sk may be negated before adding, we need to try with tweak =
          * sk as well as tweak = -sk. */
         secp256k1_scalar_set_b32(&scalar_tweak, sk, NULL);
         secp256k1_scalar_negate(&scalar_tweak, &scalar_tweak);
         secp256k1_scalar_get_b32(tweak, &scalar_tweak);
-        CHECK((secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, sk) == 0)
-              || (secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 0));
+        CHECK((secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, sk) == 0)
+              || (secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 0));
         CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk)) == 0);
     }
 
     /* Invalid pk with a valid tweak */
     memset(&internal_xonly_pk, 0, sizeof(internal_xonly_pk));
     secp256k1_testrand256(tweak);
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 0);
-    CHECK(ecount == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak));
     CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk))  == 0);
 }
 
-void test_xonly_pubkey_tweak_check(void) {
+static void test_xonly_pubkey_tweak_check(void) {
     unsigned char zeros64[64] = { 0 };
     unsigned char overflows[32];
     unsigned char sk[32];
@@ -244,60 +208,48 @@ void test_xonly_pubkey_tweak_check(void) {
     int pk_parity;
     unsigned char tweak[32];
 
-    int ecount;
-
-    set_counting_callbacks(ctx, &ecount);
-
     memset(overflows, 0xff, sizeof(overflows));
     secp256k1_testrand256(tweak);
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &internal_pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &internal_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
 
-    ecount = 0;
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &output_xonly_pk, &pk_parity, &output_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &output_xonly_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, NULL, pk_parity, &internal_xonly_pk, tweak) == 0);
-    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &output_xonly_pk, &pk_parity, &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, buf32, &output_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add_check(CTX, NULL, pk_parity, &internal_xonly_pk, tweak));
     /* invalid pk_parity value */
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, 2, &internal_xonly_pk, tweak) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, NULL, tweak) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, NULL) == 0);
-    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, 2, &internal_xonly_pk, tweak) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, NULL, tweak));
+    CHECK_ILLEGAL(CTX, secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, &internal_xonly_pk, NULL));
 
     memset(tweak, 1, sizeof(tweak));
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &internal_xonly_pk, NULL, &internal_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &output_xonly_pk, &pk_parity, &output_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, output_pk32, &output_xonly_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, pk_parity, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &internal_xonly_pk, NULL, &internal_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &output_xonly_pk, &pk_parity, &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, output_pk32, &output_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, output_pk32, pk_parity, &internal_xonly_pk, tweak) == 1);
 
     /* Wrong pk_parity */
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, !pk_parity, &internal_xonly_pk, tweak) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, output_pk32, !pk_parity, &internal_xonly_pk, tweak) == 0);
     /* Wrong public key */
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &internal_xonly_pk) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, tweak) == 0);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, buf32, &internal_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, buf32, pk_parity, &internal_xonly_pk, tweak) == 0);
 
     /* Overflowing tweak not allowed */
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, pk_parity, &internal_xonly_pk, overflows) == 0);
-    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, overflows) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, output_pk32, pk_parity, &internal_xonly_pk, overflows) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk, &internal_xonly_pk, overflows) == 0);
     CHECK(secp256k1_memcmp_var(&output_pk, zeros64, sizeof(output_pk)) == 0);
-    CHECK(ecount == 3);
 }
 
 /* Starts with an initial pubkey and recursively creates N_PUBKEYS - 1
  * additional pubkeys by calling tweak_add. Then verifies every tweak starting
  * from the last pubkey. */
 #define N_PUBKEYS 32
-void test_xonly_pubkey_tweak_recursive(void) {
+static void test_xonly_pubkey_tweak_recursive(void) {
     unsigned char sk[32];
     secp256k1_pubkey pk[N_PUBKEYS];
     unsigned char pk_serialized[32];
@@ -305,28 +257,28 @@ void test_xonly_pubkey_tweak_recursive(void) {
     int i;
 
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk[0], sk) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk[0], sk) == 1);
     /* Add tweaks */
     for (i = 0; i < N_PUBKEYS - 1; i++) {
         secp256k1_xonly_pubkey xonly_pk;
         memset(tweak[i], i + 1, sizeof(tweak[i]));
-        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk[i]) == 1);
-        CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &pk[i + 1], &xonly_pk, tweak[i]) == 1);
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, NULL, &pk[i]) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &pk[i + 1], &xonly_pk, tweak[i]) == 1);
     }
 
     /* Verify tweaks */
     for (i = N_PUBKEYS - 1; i > 0; i--) {
         secp256k1_xonly_pubkey xonly_pk;
         int pk_parity;
-        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk[i]) == 1);
-        CHECK(secp256k1_xonly_pubkey_serialize(ctx, pk_serialized, &xonly_pk) == 1);
-        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk[i - 1]) == 1);
-        CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, pk_serialized, pk_parity, &xonly_pk, tweak[i - 1]) == 1);
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk[i]) == 1);
+        CHECK(secp256k1_xonly_pubkey_serialize(CTX, pk_serialized, &xonly_pk) == 1);
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, NULL, &pk[i - 1]) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, pk_serialized, pk_parity, &xonly_pk, tweak[i - 1]) == 1);
     }
 }
 #undef N_PUBKEYS
 
-void test_keypair(void) {
+static void test_keypair(void) {
     unsigned char sk[32];
     unsigned char sk_tmp[32];
     unsigned char zeros96[96] = { 0 };
@@ -335,166 +287,136 @@ void test_keypair(void) {
     secp256k1_pubkey pk, pk_tmp;
     secp256k1_xonly_pubkey xonly_pk, xonly_pk_tmp;
     int pk_parity, pk_parity_tmp;
-    int ecount;
-    secp256k1_context *sttc = secp256k1_context_clone(secp256k1_context_static);
-
-    set_counting_callbacks(ctx, &ecount);
-    set_counting_callbacks(sttc, &ecount);
 
     CHECK(sizeof(zeros96) == sizeof(keypair));
     memset(overflows, 0xFF, sizeof(overflows));
 
     /* Test keypair_create */
-    ecount = 0;
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) != 0);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) != 0);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_keypair_create(ctx, NULL, sk) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, NULL) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_create(CTX, NULL, sk));
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_create(CTX, &keypair, NULL));
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_keypair_create(sttc, &keypair, sk) == 0);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_keypair_create(STATIC_CTX, &keypair, sk));
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) == 0);
-    CHECK(ecount == 3);
 
     /* Invalid secret key */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, zeros96) == 0);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, zeros96) == 0);
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) == 0);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, overflows) == 0);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, overflows) == 0);
     CHECK(secp256k1_memcmp_var(zeros96, &keypair, sizeof(keypair)) == 0);
 
     /* Test keypair_pub */
-    ecount = 0;
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_pub(ctx, &pk, &keypair) == 1);
-    CHECK(secp256k1_keypair_pub(ctx, NULL, &keypair) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_keypair_pub(ctx, &pk, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_pub(CTX, &pk, &keypair) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_pub(CTX, NULL, &keypair));
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_pub(CTX, &pk, NULL));
     CHECK(secp256k1_memcmp_var(zeros96, &pk, sizeof(pk)) == 0);
 
     /* Using an invalid keypair is fine for keypair_pub */
     memset(&keypair, 0, sizeof(keypair));
-    CHECK(secp256k1_keypair_pub(ctx, &pk, &keypair) == 1);
+    CHECK(secp256k1_keypair_pub(CTX, &pk, &keypair) == 1);
     CHECK(secp256k1_memcmp_var(zeros96, &pk, sizeof(pk)) == 0);
 
     /* keypair holds the same pubkey as pubkey_create */
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_pub(ctx, &pk_tmp, &keypair) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_pub(CTX, &pk_tmp, &keypair) == 1);
     CHECK(secp256k1_memcmp_var(&pk, &pk_tmp, sizeof(pk)) == 0);
 
     /** Test keypair_xonly_pub **/
-    ecount = 0;
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk, &pk_parity, &keypair) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, NULL, &pk_parity, &keypair) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk, NULL, &keypair) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk, &pk_parity, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &xonly_pk, &pk_parity, &keypair) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_pub(CTX, NULL, &pk_parity, &keypair));
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &xonly_pk, NULL, &keypair) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_pub(CTX, &xonly_pk, &pk_parity, NULL));
     CHECK(secp256k1_memcmp_var(zeros96, &xonly_pk, sizeof(xonly_pk)) == 0);
     /* Using an invalid keypair will set the xonly_pk to 0 (first reset
      * xonly_pk). */
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk, &pk_parity, &keypair) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &xonly_pk, &pk_parity, &keypair) == 1);
     memset(&keypair, 0, sizeof(keypair));
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk, &pk_parity, &keypair) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_pub(CTX, &xonly_pk, &pk_parity, &keypair));
     CHECK(secp256k1_memcmp_var(zeros96, &xonly_pk, sizeof(xonly_pk)) == 0);
-    CHECK(ecount == 3);
 
     /** keypair holds the same xonly pubkey as pubkey_create **/
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
-    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &xonly_pk_tmp, &pk_parity_tmp, &keypair) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(CTX, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &xonly_pk_tmp, &pk_parity_tmp, &keypair) == 1);
     CHECK(secp256k1_memcmp_var(&xonly_pk, &xonly_pk_tmp, sizeof(pk)) == 0);
     CHECK(pk_parity == pk_parity_tmp);
 
     /* Test keypair_seckey */
-    ecount = 0;
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_sec(ctx, sk_tmp, &keypair) == 1);
-    CHECK(secp256k1_keypair_sec(ctx, NULL, &keypair) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_keypair_sec(ctx, sk_tmp, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_sec(CTX, sk_tmp, &keypair) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_sec(CTX, NULL, &keypair));
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_sec(CTX, sk_tmp, NULL));
     CHECK(secp256k1_memcmp_var(zeros96, sk_tmp, sizeof(sk_tmp)) == 0);
 
     /* keypair returns the same seckey it got */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_sec(ctx, sk_tmp, &keypair) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_sec(CTX, sk_tmp, &keypair) == 1);
     CHECK(secp256k1_memcmp_var(sk, sk_tmp, sizeof(sk_tmp)) == 0);
 
 
     /* Using an invalid keypair is fine for keypair_seckey */
     memset(&keypair, 0, sizeof(keypair));
-    CHECK(secp256k1_keypair_sec(ctx, sk_tmp, &keypair) == 1);
+    CHECK(secp256k1_keypair_sec(CTX, sk_tmp, &keypair) == 1);
     CHECK(secp256k1_memcmp_var(zeros96, sk_tmp, sizeof(sk_tmp)) == 0);
-    secp256k1_context_destroy(sttc);
 }
 
-void test_keypair_add(void) {
+static void test_keypair_add(void) {
     unsigned char sk[32];
     secp256k1_keypair keypair;
     unsigned char overflows[32];
     unsigned char zeros96[96] = { 0 };
     unsigned char tweak[32];
     int i;
-    int ecount = 0;
-
-    set_counting_callbacks(ctx, &ecount);
 
     CHECK(sizeof(zeros96) == sizeof(keypair));
     secp256k1_testrand256(sk);
     secp256k1_testrand256(tweak);
     memset(overflows, 0xFF, 32);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
 
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, NULL, tweak) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, NULL) == 0);
-    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_tweak_add(CTX, NULL, tweak));
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_tweak_add(CTX, &keypair, NULL));
     /* This does not set the keypair to zeroes */
     CHECK(secp256k1_memcmp_var(&keypair, zeros96, sizeof(keypair)) != 0);
 
     /* Invalid tweak zeroes the keypair */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, overflows) == 0);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, overflows) == 0);
     CHECK(secp256k1_memcmp_var(&keypair, zeros96, sizeof(keypair))  == 0);
 
     /* A zero tweak is fine */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, zeros96) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, zeros96) == 1);
 
     /* Fails if the resulting keypair was (sk=0, pk=infinity) */
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         secp256k1_scalar scalar_tweak;
         secp256k1_keypair keypair_tmp;
         secp256k1_testrand256(sk);
-        CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+        CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
         memcpy(&keypair_tmp, &keypair, sizeof(keypair));
         /* Because sk may be negated before adding, we need to try with tweak =
          * sk as well as tweak = -sk. */
         secp256k1_scalar_set_b32(&scalar_tweak, sk, NULL);
         secp256k1_scalar_negate(&scalar_tweak, &scalar_tweak);
         secp256k1_scalar_get_b32(tweak, &scalar_tweak);
-        CHECK((secp256k1_keypair_xonly_tweak_add(ctx, &keypair, sk) == 0)
-              || (secp256k1_keypair_xonly_tweak_add(ctx, &keypair_tmp, tweak) == 0));
+        CHECK((secp256k1_keypair_xonly_tweak_add(CTX, &keypair, sk) == 0)
+              || (secp256k1_keypair_xonly_tweak_add(CTX, &keypair_tmp, tweak) == 0));
         CHECK(secp256k1_memcmp_var(&keypair, zeros96, sizeof(keypair)) == 0
               || secp256k1_memcmp_var(&keypair_tmp, zeros96, sizeof(keypair_tmp)) == 0);
     }
@@ -502,24 +424,20 @@ void test_keypair_add(void) {
     /* Invalid keypair with a valid tweak */
     memset(&keypair, 0, sizeof(keypair));
     secp256k1_testrand256(tweak);
-    ecount = 0;
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 0);
-    CHECK(ecount == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak));
     CHECK(secp256k1_memcmp_var(&keypair, zeros96, sizeof(keypair))  == 0);
     /* Only seckey part of keypair invalid */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
     memset(&keypair, 0, 32);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 0);
-    CHECK(ecount == 2);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak));
     /* Only pubkey part of keypair invalid */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
     memset(&keypair.data[32], 0, 64);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 0);
-    CHECK(ecount == 3);
+    CHECK_ILLEGAL(CTX, secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak));
 
     /* Check that the keypair_tweak_add implementation is correct */
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    for (i = 0; i < count; i++) {
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    for (i = 0; i < COUNT; i++) {
         secp256k1_xonly_pubkey internal_pk;
         secp256k1_xonly_pubkey output_pk;
         secp256k1_pubkey output_pk_xy;
@@ -529,27 +447,27 @@ void test_keypair_add(void) {
         int pk_parity;
 
         secp256k1_testrand256(tweak);
-        CHECK(secp256k1_keypair_xonly_pub(ctx, &internal_pk, NULL, &keypair) == 1);
-        CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
-        CHECK(secp256k1_keypair_xonly_pub(ctx, &output_pk, &pk_parity, &keypair) == 1);
+        CHECK(secp256k1_keypair_xonly_pub(CTX, &internal_pk, NULL, &keypair) == 1);
+        CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak) == 1);
+        CHECK(secp256k1_keypair_xonly_pub(CTX, &output_pk, &pk_parity, &keypair) == 1);
 
         /* Check that it passes xonly_pubkey_tweak_add_check */
-        CHECK(secp256k1_xonly_pubkey_serialize(ctx, pk32, &output_pk) == 1);
-        CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, pk32, pk_parity, &internal_pk, tweak) == 1);
+        CHECK(secp256k1_xonly_pubkey_serialize(CTX, pk32, &output_pk) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, pk32, pk_parity, &internal_pk, tweak) == 1);
 
         /* Check that the resulting pubkey matches xonly_pubkey_tweak_add */
-        CHECK(secp256k1_keypair_pub(ctx, &output_pk_xy, &keypair) == 1);
-        CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk_expected, &internal_pk, tweak) == 1);
+        CHECK(secp256k1_keypair_pub(CTX, &output_pk_xy, &keypair) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add(CTX, &output_pk_expected, &internal_pk, tweak) == 1);
         CHECK(secp256k1_memcmp_var(&output_pk_xy, &output_pk_expected, sizeof(output_pk_xy)) == 0);
 
         /* Check that the secret key in the keypair is tweaked correctly */
-        CHECK(secp256k1_keypair_sec(ctx, sk32, &keypair) == 1);
-        CHECK(secp256k1_ec_pubkey_create(ctx, &output_pk_expected, sk32) == 1);
+        CHECK(secp256k1_keypair_sec(CTX, sk32, &keypair) == 1);
+        CHECK(secp256k1_ec_pubkey_create(CTX, &output_pk_expected, sk32) == 1);
         CHECK(secp256k1_memcmp_var(&output_pk_xy, &output_pk_expected, sizeof(output_pk_xy)) == 0);
     }
 }
 
-void run_extrakeys_tests(void) {
+static void run_extrakeys_tests(void) {
     /* xonly key test cases */
     test_xonly_pubkey();
     test_xonly_pubkey_tweak();

src/modules/recovery/bench_impl.h

@@ -15,7 +15,7 @@ typedef struct {
     unsigned char sig[64];
 } bench_recover_data;
 
-void bench_recover(void* arg, int iters) {
+static void bench_recover(void* arg, int iters) {
     int i;
     bench_recover_data *data = (bench_recover_data*)arg;
     secp256k1_pubkey pubkey;
@@ -36,7 +36,7 @@ void bench_recover(void* arg, int iters) {
     }
 }
 
-void bench_recover_setup(void* arg) {
+static void bench_recover_setup(void* arg) {
     int i;
     bench_recover_data *data = (bench_recover_data*)arg;
 
@@ -48,7 +48,7 @@ void bench_recover_setup(void* arg) {
     }
 }
 
-void run_recovery_bench(int iters, int argc, char** argv) {
+static void run_recovery_bench(int iters, int argc, char** argv) {
     bench_recover_data data;
     int d = argc == 1;
 

src/modules/recovery/main_impl.h

@@ -98,7 +98,7 @@ static int secp256k1_ecdsa_sig_recover(const secp256k1_scalar *sigr, const secp2
     }
 
     secp256k1_scalar_get_b32(brx, sigr);
-    r = secp256k1_fe_set_b32(&fx, brx);
+    r = secp256k1_fe_set_b32_limit(&fx, brx);
     (void)r;
     VERIFY_CHECK(r); /* brx comes from a scalar, so is less than the order; certainly less than p */
     if (recid & 2) {

src/modules/recovery/tests_exhaustive_impl.h

@@ -10,7 +10,7 @@
 #include "main_impl.h"
 #include "../../../include/secp256k1_recovery.h"
 
-void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1_ge *group) {
+static void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1_ge *group) {
     int i, j, k;
     uint64_t iter = 0;
 
@@ -43,8 +43,7 @@ void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1
                       (k * (EXHAUSTIVE_TEST_ORDER - s)) % EXHAUSTIVE_TEST_ORDER == (i + r * j) % EXHAUSTIVE_TEST_ORDER);
                 /* The recid's second bit is for conveying overflow (R.x value >= group order).
                  * In the actual secp256k1 this is an astronomically unlikely event, but in the
-                 * small group used here, it will be the case for all points except the ones where
-                 * R.x=1 (which the group is specifically selected to have).
+                 * small group used here, it will almost certainly be the case for all points.
                  * Note that this isn't actually useful; full recovery would need to convey
                  * floor(R.x / group_order), but only one bit is used as that is sufficient
                  * in the real group. */
@@ -79,7 +78,7 @@ void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1
     }
 }
 
-void test_exhaustive_recovery_verify(const secp256k1_context *ctx, const secp256k1_ge *group) {
+static void test_exhaustive_recovery_verify(const secp256k1_context *ctx, const secp256k1_ge *group) {
     /* This is essentially a copy of test_exhaustive_verify, with recovery added */
     int s, r, msg, key;
     uint64_t iter = 0;

src/modules/recovery/tests_impl.h

@@ -28,16 +28,14 @@ static int recovery_test_nonce_function(unsigned char *nonce32, const unsigned c
     return secp256k1_testrand_bits(1);
 }
 
-void test_ecdsa_recovery_api(void) {
+static void test_ecdsa_recovery_api(void) {
     /* Setup contexts that just count errors */
-    secp256k1_context *sttc = secp256k1_context_clone(secp256k1_context_static);
     secp256k1_pubkey pubkey;
     secp256k1_pubkey recpubkey;
     secp256k1_ecdsa_signature normal_sig;
     secp256k1_ecdsa_recoverable_signature recsig;
     unsigned char privkey[32] = { 1 };
     unsigned char message[32] = { 2 };
-    int32_t ecount = 0;
     int recid = 0;
     unsigned char sig[74];
     unsigned char zero_privkey[32] = { 0 };
@@ -46,88 +44,55 @@ void test_ecdsa_recovery_api(void) {
                                        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                                        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-    secp256k1_context_set_error_callback(ctx, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_illegal_callback(ctx, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_error_callback(sttc, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_illegal_callback(sttc, counting_illegal_callback_fn, &ecount);
-
     /* Construct and verify corresponding public key. */
-    CHECK(secp256k1_ec_seckey_verify(ctx, privkey) == 1);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pubkey, privkey) == 1);
+    CHECK(secp256k1_ec_seckey_verify(CTX, privkey) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pubkey, privkey) == 1);
 
     /* Check bad contexts and NULLs for signing */
-    ecount = 0;
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, privkey, NULL, NULL) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, NULL, message, privkey, NULL, NULL) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, NULL, privkey, NULL, NULL) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, NULL, NULL, NULL) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_ecdsa_sign_recoverable(sttc, &recsig, message, privkey, NULL, NULL) == 0);
-    CHECK(ecount == 4);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, privkey, NULL, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_sign_recoverable(CTX, NULL, message, privkey, NULL, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_sign_recoverable(CTX, &recsig, NULL, privkey, NULL, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, NULL, NULL, NULL));
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_ecdsa_sign_recoverable(STATIC_CTX, &recsig, message, privkey, NULL, NULL));
     /* This will fail or succeed randomly, and in either case will not ARG_CHECK failure */
-    secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, privkey, recovery_test_nonce_function, NULL);
-    CHECK(ecount == 4);
+    secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, privkey, recovery_test_nonce_function, NULL);
     /* These will all fail, but not in ARG_CHECK way */
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, zero_privkey, NULL, NULL) == 0);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, over_privkey, NULL, NULL) == 0);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, zero_privkey, NULL, NULL) == 0);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, over_privkey, NULL, NULL) == 0);
     /* This one will succeed. */
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, privkey, NULL, NULL) == 1);
-    CHECK(ecount == 4);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, privkey, NULL, NULL) == 1);
 
     /* Check signing with a goofy nonce function */
 
     /* Check bad contexts and NULLs for recovery */
-    ecount = 0;
-    CHECK(secp256k1_ecdsa_recover(ctx, &recpubkey, &recsig, message) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_ecdsa_recover(ctx, NULL, &recsig, message) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_ecdsa_recover(ctx, &recpubkey, NULL, message) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_ecdsa_recover(ctx, &recpubkey, &recsig, NULL) == 0);
-    CHECK(ecount == 3);
+    CHECK(secp256k1_ecdsa_recover(CTX, &recpubkey, &recsig, message) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recover(CTX, NULL, &recsig, message));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recover(CTX, &recpubkey, NULL, message));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recover(CTX, &recpubkey, &recsig, NULL));
 
     /* Check NULLs for conversion */
-    CHECK(secp256k1_ecdsa_sign(ctx, &normal_sig, message, privkey, NULL, NULL) == 1);
-    ecount = 0;
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, NULL, &recsig) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &normal_sig, NULL) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &normal_sig, &recsig) == 1);
+    CHECK(secp256k1_ecdsa_sign(CTX, &normal_sig, message, privkey, NULL, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_convert(CTX, NULL, &recsig));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_convert(CTX, &normal_sig, NULL));
+    CHECK(secp256k1_ecdsa_recoverable_signature_convert(CTX, &normal_sig, &recsig) == 1);
 
     /* Check NULLs for de/serialization */
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &recsig, message, privkey, NULL, NULL) == 1);
-    ecount = 0;
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, NULL, &recid, &recsig) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, NULL, &recsig) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, NULL) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, &recsig) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &recsig, message, privkey, NULL, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, NULL, &recid, &recsig));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, sig, NULL, &recsig));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, sig, &recid, NULL));
+    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, sig, &recid, &recsig) == 1);
 
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, NULL, sig, recid) == 0);
-    CHECK(ecount == 4);
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &recsig, NULL, recid) == 0);
-    CHECK(ecount == 5);
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &recsig, sig, -1) == 0);
-    CHECK(ecount == 6);
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &recsig, sig, 5) == 0);
-    CHECK(ecount == 7);
-    /* overflow in signature will fail but not affect ecount */
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, NULL, sig, recid));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &recsig, NULL, recid));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &recsig, sig, -1));
+    CHECK_ILLEGAL(CTX, secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &recsig, sig, 5));
+    /* overflow in signature will not result in calling illegal_callback */
     memcpy(sig, over_privkey, 32);
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &recsig, sig, recid) == 0);
-    CHECK(ecount == 7);
-
-    /* cleanup */
-    secp256k1_context_destroy(sttc);
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &recsig, sig, recid) == 0);
 }
 
-void test_ecdsa_recovery_end_to_end(void) {
+static void test_ecdsa_recovery_end_to_end(void) {
     unsigned char extra[32] = {0x00};
     unsigned char privkey[32];
     unsigned char message[32];
@@ -148,45 +113,45 @@ void test_ecdsa_recovery_end_to_end(void) {
     }
 
     /* Construct and verify corresponding public key. */
-    CHECK(secp256k1_ec_seckey_verify(ctx, privkey) == 1);
-    CHECK(secp256k1_ec_pubkey_create(ctx, &pubkey, privkey) == 1);
+    CHECK(secp256k1_ec_seckey_verify(CTX, privkey) == 1);
+    CHECK(secp256k1_ec_pubkey_create(CTX, &pubkey, privkey) == 1);
 
     /* Serialize/parse compact and verify/recover. */
     extra[0] = 0;
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &rsignature[0], message, privkey, NULL, NULL) == 1);
-    CHECK(secp256k1_ecdsa_sign(ctx, &signature[0], message, privkey, NULL, NULL) == 1);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &rsignature[4], message, privkey, NULL, NULL) == 1);
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &rsignature[1], message, privkey, NULL, extra) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &rsignature[0], message, privkey, NULL, NULL) == 1);
+    CHECK(secp256k1_ecdsa_sign(CTX, &signature[0], message, privkey, NULL, NULL) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &rsignature[4], message, privkey, NULL, NULL) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &rsignature[1], message, privkey, NULL, extra) == 1);
     extra[31] = 1;
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &rsignature[2], message, privkey, NULL, extra) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &rsignature[2], message, privkey, NULL, extra) == 1);
     extra[31] = 0;
     extra[0] = 1;
-    CHECK(secp256k1_ecdsa_sign_recoverable(ctx, &rsignature[3], message, privkey, NULL, extra) == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, &rsignature[4]) == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &signature[4], &rsignature[4]) == 1);
+    CHECK(secp256k1_ecdsa_sign_recoverable(CTX, &rsignature[3], message, privkey, NULL, extra) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, sig, &recid, &rsignature[4]) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_convert(CTX, &signature[4], &rsignature[4]) == 1);
     CHECK(secp256k1_memcmp_var(&signature[4], &signature[0], 64) == 0);
-    CHECK(secp256k1_ecdsa_verify(ctx, &signature[4], message, &pubkey) == 1);
+    CHECK(secp256k1_ecdsa_verify(CTX, &signature[4], message, &pubkey) == 1);
     memset(&rsignature[4], 0, sizeof(rsignature[4]));
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsignature[4], sig, recid) == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &signature[4], &rsignature[4]) == 1);
-    CHECK(secp256k1_ecdsa_verify(ctx, &signature[4], message, &pubkey) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsignature[4], sig, recid) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_convert(CTX, &signature[4], &rsignature[4]) == 1);
+    CHECK(secp256k1_ecdsa_verify(CTX, &signature[4], message, &pubkey) == 1);
     /* Parse compact (with recovery id) and recover. */
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsignature[4], sig, recid) == 1);
-    CHECK(secp256k1_ecdsa_recover(ctx, &recpubkey, &rsignature[4], message) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsignature[4], sig, recid) == 1);
+    CHECK(secp256k1_ecdsa_recover(CTX, &recpubkey, &rsignature[4], message) == 1);
     CHECK(secp256k1_memcmp_var(&pubkey, &recpubkey, sizeof(pubkey)) == 0);
     /* Serialize/destroy/parse signature and verify again. */
-    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(ctx, sig, &recid, &rsignature[4]) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_serialize_compact(CTX, sig, &recid, &rsignature[4]) == 1);
     sig[secp256k1_testrand_bits(6)] += 1 + secp256k1_testrand_int(255);
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsignature[4], sig, recid) == 1);
-    CHECK(secp256k1_ecdsa_recoverable_signature_convert(ctx, &signature[4], &rsignature[4]) == 1);
-    CHECK(secp256k1_ecdsa_verify(ctx, &signature[4], message, &pubkey) == 0);
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsignature[4], sig, recid) == 1);
+    CHECK(secp256k1_ecdsa_recoverable_signature_convert(CTX, &signature[4], &rsignature[4]) == 1);
+    CHECK(secp256k1_ecdsa_verify(CTX, &signature[4], message, &pubkey) == 0);
     /* Recover again */
-    CHECK(secp256k1_ecdsa_recover(ctx, &recpubkey, &rsignature[4], message) == 0 ||
+    CHECK(secp256k1_ecdsa_recover(CTX, &recpubkey, &rsignature[4], message) == 0 ||
           secp256k1_memcmp_var(&pubkey, &recpubkey, sizeof(pubkey)) != 0);
 }
 
 /* Tests several edge cases. */
-void test_ecdsa_recovery_edge_cases(void) {
+static void test_ecdsa_recovery_edge_cases(void) {
     const unsigned char msg32[32] = {
         'T', 'h', 'i', 's', ' ', 'i', 's', ' ',
         'a', ' ', 'v', 'e', 'r', 'y', ' ', 's',
@@ -222,14 +187,14 @@ void test_ecdsa_recovery_edge_cases(void) {
     secp256k1_ecdsa_signature sig;
     int recid;
 
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sig64, 0));
-    CHECK(!secp256k1_ecdsa_recover(ctx, &pubkey, &rsig, msg32));
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sig64, 1));
-    CHECK(secp256k1_ecdsa_recover(ctx, &pubkey, &rsig, msg32));
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sig64, 2));
-    CHECK(!secp256k1_ecdsa_recover(ctx, &pubkey, &rsig, msg32));
-    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sig64, 3));
-    CHECK(!secp256k1_ecdsa_recover(ctx, &pubkey, &rsig, msg32));
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sig64, 0));
+    CHECK(!secp256k1_ecdsa_recover(CTX, &pubkey, &rsig, msg32));
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sig64, 1));
+    CHECK(secp256k1_ecdsa_recover(CTX, &pubkey, &rsig, msg32));
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sig64, 2));
+    CHECK(!secp256k1_ecdsa_recover(CTX, &pubkey, &rsig, msg32));
+    CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sig64, 3));
+    CHECK(!secp256k1_ecdsa_recover(CTX, &pubkey, &rsig, msg32));
 
     for (recid = 0; recid < 4; recid++) {
         int i;
@@ -274,40 +239,40 @@ void test_ecdsa_recovery_edge_cases(void) {
             0xE6, 0xAF, 0x48, 0xA0, 0x3B, 0xBF, 0xD2, 0x5E,
             0x8C, 0xD0, 0x36, 0x41, 0x45, 0x02, 0x01, 0x04
         };
-        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigb64, recid) == 1);
-        CHECK(secp256k1_ecdsa_recover(ctx, &pubkeyb, &rsig, msg32) == 1);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, sizeof(sigbder)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 1);
+        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sigb64, recid) == 1);
+        CHECK(secp256k1_ecdsa_recover(CTX, &pubkeyb, &rsig, msg32) == 1);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbder, sizeof(sigbder)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 1);
         for (recid2 = 0; recid2 < 4; recid2++) {
             secp256k1_pubkey pubkey2b;
-            CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigb64, recid2) == 1);
-            CHECK(secp256k1_ecdsa_recover(ctx, &pubkey2b, &rsig, msg32) == 1);
+            CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sigb64, recid2) == 1);
+            CHECK(secp256k1_ecdsa_recover(CTX, &pubkey2b, &rsig, msg32) == 1);
             /* Verifying with (order + r,4) should always fail. */
-            CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderlong, sizeof(sigbderlong)) == 1);
-            CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0);
+            CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderlong, sizeof(sigbderlong)) == 1);
+            CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 0);
         }
         /* DER parsing tests. */
         /* Zero length r/s. */
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder_zr, sizeof(sigcder_zr)) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder_zs, sizeof(sigcder_zs)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigcder_zr, sizeof(sigcder_zr)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigcder_zs, sizeof(sigcder_zs)) == 0);
         /* Leading zeros. */
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt1, sizeof(sigbderalt1)) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt2, sizeof(sigbderalt2)) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt3, sizeof(sigbderalt3)) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt4, sizeof(sigbderalt4)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt1, sizeof(sigbderalt1)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt2, sizeof(sigbderalt2)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt3, sizeof(sigbderalt3)) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt4, sizeof(sigbderalt4)) == 0);
         sigbderalt3[4] = 1;
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt3, sizeof(sigbderalt3)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt3, sizeof(sigbderalt3)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 0);
         sigbderalt4[7] = 1;
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbderalt4, sizeof(sigbderalt4)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbderalt4, sizeof(sigbderalt4)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 0);
         /* Damage signature. */
         sigbder[7]++;
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, sizeof(sigbder)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbder, sizeof(sigbder)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 0);
         sigbder[7]--;
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, 6) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, sizeof(sigbder) - 1) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbder, 6) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbder, sizeof(sigbder) - 1) == 0);
         for(i = 0; i < 8; i++) {
             int c;
             unsigned char orig = sigbder[i];
@@ -317,7 +282,7 @@ void test_ecdsa_recovery_edge_cases(void) {
                     continue;
                 }
                 sigbder[i] = c;
-                CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigbder, sizeof(sigbder)) == 0 || secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyb) == 0);
+                CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigbder, sizeof(sigbder)) == 0 || secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyb) == 0);
             }
             sigbder[i] = orig;
         }
@@ -338,33 +303,33 @@ void test_ecdsa_recovery_edge_cases(void) {
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
         };
         secp256k1_pubkey pubkeyc;
-        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigc64, 0) == 1);
-        CHECK(secp256k1_ecdsa_recover(ctx, &pubkeyc, &rsig, msg32) == 1);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder, sizeof(sigcder)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyc) == 1);
+        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sigc64, 0) == 1);
+        CHECK(secp256k1_ecdsa_recover(CTX, &pubkeyc, &rsig, msg32) == 1);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigcder, sizeof(sigcder)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyc) == 1);
         sigcder[4] = 0;
         sigc64[31] = 0;
-        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigc64, 0) == 1);
-        CHECK(secp256k1_ecdsa_recover(ctx, &pubkeyb, &rsig, msg32) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder, sizeof(sigcder)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyc) == 0);
+        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sigc64, 0) == 1);
+        CHECK(secp256k1_ecdsa_recover(CTX, &pubkeyb, &rsig, msg32) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigcder, sizeof(sigcder)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyc) == 0);
         sigcder[4] = 1;
         sigcder[7] = 0;
         sigc64[31] = 1;
         sigc64[63] = 0;
-        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rsig, sigc64, 0) == 1);
-        CHECK(secp256k1_ecdsa_recover(ctx, &pubkeyb, &rsig, msg32) == 0);
-        CHECK(secp256k1_ecdsa_signature_parse_der(ctx, &sig, sigcder, sizeof(sigcder)) == 1);
-        CHECK(secp256k1_ecdsa_verify(ctx, &sig, msg32, &pubkeyc) == 0);
+        CHECK(secp256k1_ecdsa_recoverable_signature_parse_compact(CTX, &rsig, sigc64, 0) == 1);
+        CHECK(secp256k1_ecdsa_recover(CTX, &pubkeyb, &rsig, msg32) == 0);
+        CHECK(secp256k1_ecdsa_signature_parse_der(CTX, &sig, sigcder, sizeof(sigcder)) == 1);
+        CHECK(secp256k1_ecdsa_verify(CTX, &sig, msg32, &pubkeyc) == 0);
     }
 }
 
-void run_recovery_tests(void) {
+static void run_recovery_tests(void) {
     int i;
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         test_ecdsa_recovery_api();
     }
-    for (i = 0; i < 64*count; i++) {
+    for (i = 0; i < 64*COUNT; i++) {
         test_ecdsa_recovery_end_to_end();
     }
     test_ecdsa_recovery_edge_cases();

src/modules/schnorrsig/bench_impl.h

@@ -21,7 +21,7 @@ typedef struct {
     const unsigned char **msgs;
 } bench_schnorrsig_data;
 
-void bench_schnorrsig_sign(void* arg, int iters) {
+static void bench_schnorrsig_sign(void* arg, int iters) {
     bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
     int i;
     unsigned char msg[MSGLEN] = {0};
@@ -34,7 +34,7 @@ void bench_schnorrsig_sign(void* arg, int iters) {
     }
 }
 
-void bench_schnorrsig_verify(void* arg, int iters) {
+static void bench_schnorrsig_verify(void* arg, int iters) {
     bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
     int i;
 
@@ -45,7 +45,7 @@ void bench_schnorrsig_verify(void* arg, int iters) {
     }
 }
 
-void run_schnorrsig_bench(int iters, int argc, char** argv) {
+static void run_schnorrsig_bench(int iters, int argc, char** argv) {
     int i;
     bench_schnorrsig_data data;
     int d = argc == 1;

src/modules/schnorrsig/main_impl.h

@@ -232,7 +232,7 @@ int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned cha
     ARG_CHECK(msg != NULL || msglen == 0);
     ARG_CHECK(pubkey != NULL);
 
-    if (!secp256k1_fe_set_b32(&rx, &sig64[0])) {
+    if (!secp256k1_fe_set_b32_limit(&rx, &sig64[0])) {
         return 0;
     }
 
@@ -261,7 +261,7 @@ int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned cha
 
     secp256k1_fe_normalize_var(&r.y);
     return !secp256k1_fe_is_odd(&r.y) &&
-           secp256k1_fe_equal_var(&rx, &r.x);
+           secp256k1_fe_equal(&rx, &r.x);
 }
 
 #endif

src/modules/schnorrsig/tests_exhaustive_impl.h

@@ -110,15 +110,15 @@ static void test_exhaustive_schnorrsig_verify(const secp256k1_context *ctx, cons
                 if (!e_done[e]) {
                     /* Iterate over the possible valid last 32 bytes in the signature.
                        0..order=that s value; order+1=random bytes */
-                    int count_valid = 0, s;
+                    int count_valid = 0;
+                    unsigned int s;
                     for (s = 0; s <= EXHAUSTIVE_TEST_ORDER + 1; ++s) {
                         int expect_valid, valid;
                         if (s <= EXHAUSTIVE_TEST_ORDER) {
-                            secp256k1_scalar s_s;
-                            secp256k1_scalar_set_int(&s_s, s);
-                            secp256k1_scalar_get_b32(sig64 + 32, &s_s);
+                            memset(sig64 + 32, 0, 32);
+                            secp256k1_write_be32(sig64 + 60, s);
                             expect_valid = actual_k != -1 && s != EXHAUSTIVE_TEST_ORDER &&
-                                           (s_s == (actual_k + actual_d * e) % EXHAUSTIVE_TEST_ORDER);
+                                           (s == (actual_k + actual_d * e) % EXHAUSTIVE_TEST_ORDER);
                         } else {
                             secp256k1_testrand256(sig64 + 32);
                             expect_valid = 0;

src/modules/schnorrsig/tests_impl.h

@@ -12,7 +12,7 @@
 /* Checks that a bit flip in the n_flip-th argument (that has n_bytes many
  * bytes) changes the hash function
  */
-void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, size_t n_bytes, size_t msglen, size_t algolen) {
+static void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, size_t n_bytes, size_t msglen, size_t algolen) {
     unsigned char nonces[2][32];
     CHECK(nonce_function_bip340(nonces[0], args[0], msglen, args[1], args[2], args[3], algolen, args[4]) == 1);
     secp256k1_testrand_flip(args[n_flip], n_bytes);
@@ -20,18 +20,7 @@ void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, size_t n
     CHECK(secp256k1_memcmp_var(nonces[0], nonces[1], 32) != 0);
 }
 
-/* Tests for the equality of two sha256 structs. This function only produces a
- * correct result if an integer multiple of 64 many bytes have been written
- * into the hash functions. */
-void test_sha256_eq(const secp256k1_sha256 *sha1, const secp256k1_sha256 *sha2) {
-    /* Is buffer fully consumed? */
-    CHECK((sha1->bytes & 0x3F) == 0);
-
-    CHECK(sha1->bytes == sha2->bytes);
-    CHECK(secp256k1_memcmp_var(sha1->s, sha2->s, sizeof(sha1->s)) == 0);
-}
-
-void run_nonce_function_bip340_tests(void) {
+static void run_nonce_function_bip340_tests(void) {
     unsigned char tag[13] = "BIP0340/nonce";
     unsigned char aux_tag[11] = "BIP0340/aux";
     unsigned char algo[13] = "BIP0340/nonce";
@@ -72,7 +61,7 @@ void run_nonce_function_bip340_tests(void) {
     args[2] = pk;
     args[3] = algo;
     args[4] = aux_rand;
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         nonce_function_bip340_bitflip(args, 0, 32, msglen, algolen);
         nonce_function_bip340_bitflip(args, 1, 32, msglen, algolen);
         nonce_function_bip340_bitflip(args, 2, 32, msglen, algolen);
@@ -90,7 +79,7 @@ void run_nonce_function_bip340_tests(void) {
     secp256k1_testrand_bytes_test(algo, algolen);
     CHECK(nonce_function_bip340(nonce, msg, msglen, key, pk, algo, algolen, NULL) == 1);
 
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         unsigned char nonce2[32];
         uint32_t offset = secp256k1_testrand_int(msglen - 1);
         size_t msglen_tmp = (msglen + offset) % msglen;
@@ -114,7 +103,7 @@ void run_nonce_function_bip340_tests(void) {
     CHECK(secp256k1_memcmp_var(nonce_z, nonce, 32) == 0);
 }
 
-void test_schnorrsig_api(void) {
+static void test_schnorrsig_api(void) {
     unsigned char sk1[32];
     unsigned char sk2[32];
     unsigned char sk3[32];
@@ -127,83 +116,48 @@ void test_schnorrsig_api(void) {
     secp256k1_schnorrsig_extraparams extraparams = SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT;
     secp256k1_schnorrsig_extraparams invalid_extraparams = {{ 0 }, NULL, NULL};
 
-    /** setup **/
-    secp256k1_context *sttc = secp256k1_context_clone(secp256k1_context_static);
-    int ecount;
-
-    secp256k1_context_set_error_callback(ctx, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_illegal_callback(ctx, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_error_callback(sttc, counting_illegal_callback_fn, &ecount);
-    secp256k1_context_set_illegal_callback(sttc, counting_illegal_callback_fn, &ecount);
-
     secp256k1_testrand256(sk1);
     secp256k1_testrand256(sk2);
     secp256k1_testrand256(sk3);
     secp256k1_testrand256(msg);
-    CHECK(secp256k1_keypair_create(ctx, &keypairs[0], sk1) == 1);
-    CHECK(secp256k1_keypair_create(ctx, &keypairs[1], sk2) == 1);
-    CHECK(secp256k1_keypair_create(ctx, &keypairs[2], sk3) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[0], NULL, &keypairs[0]) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[1], NULL, &keypairs[1]) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[2], NULL, &keypairs[2]) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypairs[0], sk1) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypairs[1], sk2) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypairs[2], sk3) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk[0], NULL, &keypairs[0]) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk[1], NULL, &keypairs[1]) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk[2], NULL, &keypairs[2]) == 1);
     memset(&zero_pk, 0, sizeof(zero_pk));
 
     /** main test body **/
-    ecount = 0;
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, &keypairs[0], NULL) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, NULL, msg, &keypairs[0], NULL) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, NULL, &keypairs[0], NULL) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, NULL, NULL) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, &invalid_keypair, NULL) == 0);
-    CHECK(ecount == 4);
-    CHECK(secp256k1_schnorrsig_sign32(sttc, sig, msg, &keypairs[0], NULL) == 0);
-    CHECK(ecount == 5);
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig, msg, &keypairs[0], NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign32(CTX, NULL, msg, &keypairs[0], NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign32(CTX, sig, NULL, &keypairs[0], NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign32(CTX, sig, msg, NULL, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign32(CTX, sig, msg, &invalid_keypair, NULL));
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_schnorrsig_sign32(STATIC_CTX, sig, msg, &keypairs[0], NULL));
 
-    ecount = 0;
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypairs[0], &extraparams) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, NULL, msg, sizeof(msg), &keypairs[0], &extraparams) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, NULL, sizeof(msg), &keypairs[0], &extraparams) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, NULL, 0, &keypairs[0], &extraparams) == 1);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), NULL, &extraparams) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &invalid_keypair, &extraparams) == 0);
-    CHECK(ecount == 4);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypairs[0], NULL) == 1);
-    CHECK(ecount == 4);
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypairs[0], &invalid_extraparams) == 0);
-    CHECK(ecount == 5);
-    CHECK(secp256k1_schnorrsig_sign_custom(sttc, sig, msg, sizeof(msg), &keypairs[0], &extraparams) == 0);
-    CHECK(ecount == 6);
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypairs[0], &extraparams) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign_custom(CTX, NULL, msg, sizeof(msg), &keypairs[0], &extraparams));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign_custom(CTX, sig, NULL, sizeof(msg), &keypairs[0], &extraparams));
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, NULL, 0, &keypairs[0], &extraparams) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), NULL, &extraparams));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &invalid_keypair, &extraparams));
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypairs[0], NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypairs[0], &invalid_extraparams));
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_schnorrsig_sign_custom(STATIC_CTX, sig, msg, sizeof(msg), &keypairs[0], &extraparams));
 
-    ecount = 0;
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, &keypairs[0], NULL) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &pk[0]) == 1);
-    CHECK(ecount == 0);
-    CHECK(secp256k1_schnorrsig_verify(ctx, NULL, msg, sizeof(msg), &pk[0]) == 0);
-    CHECK(ecount == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, NULL, sizeof(msg), &pk[0]) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, NULL, 0, &pk[0]) == 0);
-    CHECK(ecount == 2);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), NULL) == 0);
-    CHECK(ecount == 3);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &zero_pk) == 0);
-    CHECK(ecount == 4);
-
-    secp256k1_context_destroy(sttc);
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig, msg, &keypairs[0], NULL) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &pk[0]) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_verify(CTX, NULL, msg, sizeof(msg), &pk[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_verify(CTX, sig, NULL, sizeof(msg), &pk[0]));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, NULL, 0, &pk[0]) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &zero_pk));
 }
 
 /* Checks that hash initialized by secp256k1_schnorrsig_sha256_tagged has the
  * expected state. */
-void test_schnorrsig_sha256_tagged(void) {
+static void test_schnorrsig_sha256_tagged(void) {
     unsigned char tag[17] = "BIP0340/challenge";
     secp256k1_sha256 sha;
     secp256k1_sha256 sha_optimized;
@@ -215,33 +169,41 @@ void test_schnorrsig_sha256_tagged(void) {
 
 /* Helper function for schnorrsig_bip_vectors
  * Signs the message and checks that it's the same as expected_sig. */
-void test_schnorrsig_bip_vectors_check_signing(const unsigned char *sk, const unsigned char *pk_serialized, const unsigned char *aux_rand, const unsigned char *msg32, const unsigned char *expected_sig) {
+static void test_schnorrsig_bip_vectors_check_signing(const unsigned char *sk, const unsigned char *pk_serialized, const unsigned char *aux_rand, const unsigned char *msg, size_t msglen, const unsigned char *expected_sig) {
     unsigned char sig[64];
     secp256k1_keypair keypair;
     secp256k1_xonly_pubkey pk, pk_expected;
 
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg32, &keypair, aux_rand));
-    CHECK(secp256k1_memcmp_var(sig, expected_sig, 64) == 0);
+    secp256k1_schnorrsig_extraparams extraparams = SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT;
+    extraparams.ndata = (unsigned char*)aux_rand;
 
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk_expected, pk_serialized));
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk));
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, msglen, &keypair, &extraparams));
+    CHECK(secp256k1_memcmp_var(sig, expected_sig, 64) == 0);
+    if (msglen == 32) {
+        memset(sig, 0, 64);
+        CHECK(secp256k1_schnorrsig_sign32(CTX, sig, msg, &keypair, aux_rand));
+        CHECK(secp256k1_memcmp_var(sig, expected_sig, 64) == 0);
+    }
+
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &pk_expected, pk_serialized));
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk, NULL, &keypair));
     CHECK(secp256k1_memcmp_var(&pk, &pk_expected, sizeof(pk)) == 0);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg32, 32, &pk));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, msglen, &pk));
 }
 
 /* Helper function for schnorrsig_bip_vectors
  * Checks that both verify and verify_batch (TODO) return the same value as expected. */
-void test_schnorrsig_bip_vectors_check_verify(const unsigned char *pk_serialized, const unsigned char *msg32, const unsigned char *sig, int expected) {
+static void test_schnorrsig_bip_vectors_check_verify(const unsigned char *pk_serialized, const unsigned char *msg, size_t msglen, const unsigned char *sig, int expected) {
     secp256k1_xonly_pubkey pk;
 
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk, pk_serialized));
-    CHECK(expected == secp256k1_schnorrsig_verify(ctx, sig, msg32, 32, &pk));
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &pk, pk_serialized));
+    CHECK(expected == secp256k1_schnorrsig_verify(CTX, sig, msg, msglen, &pk));
 }
 
 /* Test vectors according to BIP-340 ("Schnorr Signatures for secp256k1"). See
  * https://github.com/bitcoin/bips/blob/master/bip-0340/test-vectors.csv. */
-void test_schnorrsig_bip_vectors(void) {
+static void test_schnorrsig_bip_vectors(void) {
     {
         /* Test vector 0 */
         const unsigned char sk[32] = {
@@ -256,7 +218,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xB5, 0x31, 0xC8, 0x45, 0x83, 0x6F, 0x99, 0xB0,
             0x86, 0x01, 0xF1, 0x13, 0xBC, 0xE0, 0x36, 0xF9
         };
-        unsigned char aux_rand[32] = {
+        const unsigned char aux_rand[32] = {
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -278,8 +240,8 @@ void test_schnorrsig_bip_vectors(void) {
             0xEB, 0xEE, 0xE8, 0xFD, 0xB2, 0x17, 0x2F, 0x47,
             0x7D, 0xF4, 0x90, 0x0D, 0x31, 0x05, 0x36, 0xC0
         };
-        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
     {
         /* Test vector 1 */
@@ -295,7 +257,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
             0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
         };
-        unsigned char aux_rand[32] = {
+        const unsigned char aux_rand[32] = {
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -317,8 +279,8 @@ void test_schnorrsig_bip_vectors(void) {
             0x89, 0x7E, 0xFC, 0xB6, 0x39, 0xEA, 0x87, 0x1C,
             0xFA, 0x95, 0xF6, 0xDE, 0x33, 0x9E, 0x4B, 0x0A
         };
-        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
     {
         /* Test vector 2 */
@@ -334,7 +296,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x01, 0x39, 0x71, 0x53, 0x09, 0xB0, 0x86, 0xC9,
             0x60, 0xE1, 0x8F, 0xD9, 0x69, 0x77, 0x4E, 0xB8
         };
-        unsigned char aux_rand[32] = {
+        const unsigned char aux_rand[32] = {
             0xC8, 0x7A, 0xA5, 0x38, 0x24, 0xB4, 0xD7, 0xAE,
             0x2E, 0xB0, 0x35, 0xA2, 0xB5, 0xBB, 0xBC, 0xCC,
             0x08, 0x0E, 0x76, 0xCD, 0xC6, 0xD1, 0x69, 0x2C,
@@ -356,8 +318,8 @@ void test_schnorrsig_bip_vectors(void) {
             0x7A, 0xDE, 0xA9, 0x8D, 0x82, 0xF8, 0x48, 0x1E,
             0x0E, 0x1E, 0x03, 0x67, 0x4A, 0x6F, 0x3F, 0xB7
         };
-        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
     {
         /* Test vector 3 */
@@ -373,7 +335,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x3A, 0x0D, 0x95, 0xFB, 0xF2, 0x1D, 0x46, 0x8A,
             0x1B, 0x33, 0xF8, 0xC1, 0x60, 0xD8, 0xF5, 0x17
         };
-        unsigned char aux_rand[32] = {
+        const unsigned char aux_rand[32] = {
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
@@ -395,8 +357,8 @@ void test_schnorrsig_bip_vectors(void) {
             0xF2, 0x5F, 0xD7, 0x88, 0x81, 0xEB, 0xB3, 0x27,
             0x71, 0xFC, 0x59, 0x22, 0xEF, 0xC6, 0x6E, 0xA3
         };
-        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
     {
         /* Test vector 4 */
@@ -422,7 +384,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x60, 0xCB, 0x71, 0xC0, 0x4E, 0x80, 0xF5, 0x93,
             0x06, 0x0B, 0x07, 0xD2, 0x83, 0x08, 0xD7, 0xF4
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
     {
         /* Test vector 5 */
@@ -434,7 +396,7 @@ void test_schnorrsig_bip_vectors(void) {
         };
         secp256k1_xonly_pubkey pk_parsed;
         /* No need to check the signature of the test vector as parsing the pubkey already fails */
-        CHECK(!secp256k1_xonly_pubkey_parse(ctx, &pk_parsed, pk));
+        CHECK(!secp256k1_xonly_pubkey_parse(CTX, &pk_parsed, pk));
     }
     {
         /* Test vector 6 */
@@ -460,7 +422,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x7A, 0x73, 0xC6, 0x43, 0xE1, 0x66, 0xBE, 0x5E,
             0xBE, 0xAF, 0xA3, 0x4B, 0x1A, 0xC5, 0x53, 0xE2
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 7 */
@@ -486,7 +448,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x62, 0x2A, 0x95, 0x4C, 0xFE, 0x54, 0x57, 0x35,
             0xAA, 0xEA, 0x51, 0x34, 0xFC, 0xCD, 0xB2, 0xBD
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 8 */
@@ -512,7 +474,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xE8, 0xD7, 0xC9, 0x3E, 0x00, 0xC5, 0xED, 0x0C,
             0x18, 0x34, 0xFF, 0x0D, 0x0C, 0x2E, 0x6D, 0xA6
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 9 */
@@ -538,7 +500,7 @@ void test_schnorrsig_bip_vectors(void) {
             0x4F, 0xB7, 0x34, 0x76, 0xF0, 0xD5, 0x94, 0xDC,
             0xB6, 0x5C, 0x64, 0x25, 0xBD, 0x18, 0x60, 0x51
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 10 */
@@ -564,7 +526,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xDB, 0xA8, 0x7F, 0x11, 0xAC, 0x67, 0x54, 0xF9,
             0x37, 0x80, 0xD5, 0xA1, 0x83, 0x7C, 0xF1, 0x97
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 11 */
@@ -590,7 +552,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xD1, 0xD7, 0x13, 0xA8, 0xAE, 0x82, 0xB3, 0x2F,
             0xA7, 0x9D, 0x5F, 0x7F, 0xC4, 0x07, 0xD3, 0x9B
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 12 */
@@ -616,7 +578,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xD1, 0xD7, 0x13, 0xA8, 0xAE, 0x82, 0xB3, 0x2F,
             0xA7, 0x9D, 0x5F, 0x7F, 0xC4, 0x07, 0xD3, 0x9B
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 13 */
@@ -642,7 +604,7 @@ void test_schnorrsig_bip_vectors(void) {
             0xBA, 0xAE, 0xDC, 0xE6, 0xAF, 0x48, 0xA0, 0x3B,
             0xBF, 0xD2, 0x5E, 0x8C, 0xD0, 0x36, 0x41, 0x41
         };
-        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 0);
     }
     {
         /* Test vector 14 */
@@ -654,7 +616,148 @@ void test_schnorrsig_bip_vectors(void) {
         };
         secp256k1_xonly_pubkey pk_parsed;
         /* No need to check the signature of the test vector as parsing the pubkey already fails */
-        CHECK(!secp256k1_xonly_pubkey_parse(ctx, &pk_parsed, pk));
+        CHECK(!secp256k1_xonly_pubkey_parse(CTX, &pk_parsed, pk));
+    }
+    {
+        /* Test vector 15 */
+        const unsigned char sk[32] = {
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+        };
+        const unsigned char pk[32] = {
+            0x77, 0x8C, 0xAA, 0x53, 0xB4, 0x39, 0x3A, 0xC4,
+            0x67, 0x77, 0x4D, 0x09, 0x49, 0x7A, 0x87, 0x22,
+            0x4B, 0xF9, 0xFA, 0xB6, 0xF6, 0xE6, 0x8B, 0x23,
+            0x08, 0x64, 0x97, 0x32, 0x4D, 0x6F, 0xD1, 0x17,
+        };
+        const unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        };
+        /* const unsigned char msg[0] = {}; */
+        const unsigned char sig[64] = {
+            0x71, 0x53, 0x5D, 0xB1, 0x65, 0xEC, 0xD9, 0xFB,
+            0xBC, 0x04, 0x6E, 0x5F, 0xFA, 0xEA, 0x61, 0x18,
+            0x6B, 0xB6, 0xAD, 0x43, 0x67, 0x32, 0xFC, 0xCC,
+            0x25, 0x29, 0x1A, 0x55, 0x89, 0x54, 0x64, 0xCF,
+            0x60, 0x69, 0xCE, 0x26, 0xBF, 0x03, 0x46, 0x62,
+            0x28, 0xF1, 0x9A, 0x3A, 0x62, 0xDB, 0x8A, 0x64,
+            0x9F, 0x2D, 0x56, 0x0F, 0xAC, 0x65, 0x28, 0x27,
+            0xD1, 0xAF, 0x05, 0x74, 0xE4, 0x27, 0xAB, 0x63,
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, NULL, 0, sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, NULL, 0, sig, 1);
+    }
+    {
+        /* Test vector 16 */
+        const unsigned char sk[32] = {
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+        };
+        const unsigned char pk[32] = {
+            0x77, 0x8C, 0xAA, 0x53, 0xB4, 0x39, 0x3A, 0xC4,
+            0x67, 0x77, 0x4D, 0x09, 0x49, 0x7A, 0x87, 0x22,
+            0x4B, 0xF9, 0xFA, 0xB6, 0xF6, 0xE6, 0x8B, 0x23,
+            0x08, 0x64, 0x97, 0x32, 0x4D, 0x6F, 0xD1, 0x17,
+        };
+        const unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        };
+        const unsigned char msg[] = { 0x11 };
+        const unsigned char sig[64] = {
+            0x08, 0xA2, 0x0A, 0x0A, 0xFE, 0xF6, 0x41, 0x24,
+            0x64, 0x92, 0x32, 0xE0, 0x69, 0x3C, 0x58, 0x3A,
+            0xB1, 0xB9, 0x93, 0x4A, 0xE6, 0x3B, 0x4C, 0x35,
+            0x11, 0xF3, 0xAE, 0x11, 0x34, 0xC6, 0xA3, 0x03,
+            0xEA, 0x31, 0x73, 0xBF, 0xEA, 0x66, 0x83, 0xBD,
+            0x10, 0x1F, 0xA5, 0xAA, 0x5D, 0xBC, 0x19, 0x96,
+            0xFE, 0x7C, 0xAC, 0xFC, 0x5A, 0x57, 0x7D, 0x33,
+            0xEC, 0x14, 0x56, 0x4C, 0xEC, 0x2B, 0xAC, 0xBF,
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
+    }
+    {
+        /* Test vector 17 */
+        const unsigned char sk[32] = {
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+        };
+        const unsigned char pk[32] = {
+            0x77, 0x8C, 0xAA, 0x53, 0xB4, 0x39, 0x3A, 0xC4,
+            0x67, 0x77, 0x4D, 0x09, 0x49, 0x7A, 0x87, 0x22,
+            0x4B, 0xF9, 0xFA, 0xB6, 0xF6, 0xE6, 0x8B, 0x23,
+            0x08, 0x64, 0x97, 0x32, 0x4D, 0x6F, 0xD1, 0x17,
+        };
+        const unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        };
+        const unsigned char msg[] = {
+            0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+            0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10,
+            0x11,
+        };
+        const unsigned char sig[64] = {
+            0x51, 0x30, 0xF3, 0x9A, 0x40, 0x59, 0xB4, 0x3B,
+            0xC7, 0xCA, 0xC0, 0x9A, 0x19, 0xEC, 0xE5, 0x2B,
+            0x5D, 0x86, 0x99, 0xD1, 0xA7, 0x1E, 0x3C, 0x52,
+            0xDA, 0x9A, 0xFD, 0xB6, 0xB5, 0x0A, 0xC3, 0x70,
+            0xC4, 0xA4, 0x82, 0xB7, 0x7B, 0xF9, 0x60, 0xF8,
+            0x68, 0x15, 0x40, 0xE2, 0x5B, 0x67, 0x71, 0xEC,
+            0xE1, 0xE5, 0xA3, 0x7F, 0xD8, 0x0E, 0x5A, 0x51,
+            0x89, 0x7C, 0x55, 0x66, 0xA9, 0x7E, 0xA5, 0xA5,
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
+    }
+    {
+        /* Test vector 18 */
+        const unsigned char sk[32] = {
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+            0x03, 0x40, 0x03, 0x40, 0x03, 0x40, 0x03, 0x40,
+        };
+        const unsigned char pk[32] = {
+            0x77, 0x8C, 0xAA, 0x53, 0xB4, 0x39, 0x3A, 0xC4,
+            0x67, 0x77, 0x4D, 0x09, 0x49, 0x7A, 0x87, 0x22,
+            0x4B, 0xF9, 0xFA, 0xB6, 0xF6, 0xE6, 0x8B, 0x23,
+            0x08, 0x64, 0x97, 0x32, 0x4D, 0x6F, 0xD1, 0x17,
+        };
+        const unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        };
+        const unsigned char sig[64] = {
+            0x40, 0x3B, 0x12, 0xB0, 0xD8, 0x55, 0x5A, 0x34,
+            0x41, 0x75, 0xEA, 0x7E, 0xC7, 0x46, 0x56, 0x63,
+            0x03, 0x32, 0x1E, 0x5D, 0xBF, 0xA8, 0xBE, 0x6F,
+            0x09, 0x16, 0x35, 0x16, 0x3E, 0xCA, 0x79, 0xA8,
+            0x58, 0x5E, 0xD3, 0xE3, 0x17, 0x08, 0x07, 0xE7,
+            0xC0, 0x3B, 0x72, 0x0F, 0xC5, 0x4C, 0x7B, 0x23,
+            0x89, 0x7F, 0xCB, 0xA0, 0xE9, 0xD0, 0xB4, 0xA0,
+            0x68, 0x94, 0xCF, 0xD2, 0x49, 0xF2, 0x23, 0x67,
+        };
+        unsigned char msg[100];
+        memset(msg, 0x99, sizeof(msg));
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sizeof(msg), sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sizeof(msg), sig, 1);
     }
 }
 
@@ -699,7 +802,7 @@ static int nonce_function_overflowing(unsigned char *nonce32, const unsigned cha
     return 1;
 }
 
-void test_schnorrsig_sign(void) {
+static void test_schnorrsig_sign(void) {
     unsigned char sk[32];
     secp256k1_xonly_pubkey pk;
     secp256k1_keypair keypair;
@@ -712,36 +815,36 @@ void test_schnorrsig_sign(void) {
 
     secp256k1_testrand256(sk);
     secp256k1_testrand256(aux_rand);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, &keypair, NULL) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &pk));
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk));
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk, NULL, &keypair));
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig, msg, &keypair, NULL) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &pk));
     /* Check that deprecated alias gives the same result */
-    CHECK(secp256k1_schnorrsig_sign(ctx, sig2, msg, &keypair, NULL) == 1);
+    CHECK(secp256k1_schnorrsig_sign(CTX, sig2, msg, &keypair, NULL) == 1);
     CHECK(secp256k1_memcmp_var(sig, sig2, sizeof(sig)) == 0);
 
     /* Test different nonce functions */
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &pk));
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &pk));
     memset(sig, 1, sizeof(sig));
     extraparams.noncefp = nonce_function_failing;
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 0);
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypair, &extraparams) == 0);
     CHECK(secp256k1_memcmp_var(sig, zeros64, sizeof(sig)) == 0);
     memset(&sig, 1, sizeof(sig));
     extraparams.noncefp = nonce_function_0;
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 0);
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypair, &extraparams) == 0);
     CHECK(secp256k1_memcmp_var(sig, zeros64, sizeof(sig)) == 0);
     memset(&sig, 1, sizeof(sig));
     extraparams.noncefp = nonce_function_overflowing;
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &pk));
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &pk));
 
     /* When using the default nonce function, schnorrsig_sign_custom produces
      * the same result as schnorrsig_sign with aux_rand = extraparams.ndata */
     extraparams.noncefp = NULL;
     extraparams.ndata = aux_rand;
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig2, msg, &keypair, extraparams.ndata) == 1);
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig, msg, sizeof(msg), &keypair, &extraparams) == 1);
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig2, msg, &keypair, extraparams.ndata) == 1);
     CHECK(secp256k1_memcmp_var(sig, sig2, sizeof(sig)) == 0);
 }
 
@@ -749,7 +852,7 @@ void test_schnorrsig_sign(void) {
 /* Creates N_SIGS valid signatures and verifies them with verify and
  * verify_batch (TODO). Then flips some bits and checks that verification now
  * fails. */
-void test_schnorrsig_sign_verify(void) {
+static void test_schnorrsig_sign_verify(void) {
     unsigned char sk[32];
     unsigned char msg[N_SIGS][32];
     unsigned char sig[N_SIGS][64];
@@ -759,13 +862,13 @@ void test_schnorrsig_sign_verify(void) {
     secp256k1_scalar s;
 
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk));
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &pk, NULL, &keypair));
 
     for (i = 0; i < N_SIGS; i++) {
         secp256k1_testrand256(msg[i]);
-        CHECK(secp256k1_schnorrsig_sign32(ctx, sig[i], msg[i], &keypair, NULL));
-        CHECK(secp256k1_schnorrsig_verify(ctx, sig[i], msg[i], sizeof(msg[i]), &pk));
+        CHECK(secp256k1_schnorrsig_sign32(CTX, sig[i], msg[i], &keypair, NULL));
+        CHECK(secp256k1_schnorrsig_verify(CTX, sig[i], msg[i], sizeof(msg[i]), &pk));
     }
 
     {
@@ -775,40 +878,40 @@ void test_schnorrsig_sign_verify(void) {
         size_t byte_idx = secp256k1_testrand_bits(5);
         unsigned char xorbyte = secp256k1_testrand_int(254)+1;
         sig[sig_idx][byte_idx] ^= xorbyte;
-        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
+        CHECK(!secp256k1_schnorrsig_verify(CTX, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
         sig[sig_idx][byte_idx] ^= xorbyte;
 
         byte_idx = secp256k1_testrand_bits(5);
         sig[sig_idx][32+byte_idx] ^= xorbyte;
-        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
+        CHECK(!secp256k1_schnorrsig_verify(CTX, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
         sig[sig_idx][32+byte_idx] ^= xorbyte;
 
         byte_idx = secp256k1_testrand_bits(5);
         msg[sig_idx][byte_idx] ^= xorbyte;
-        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
+        CHECK(!secp256k1_schnorrsig_verify(CTX, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
         msg[sig_idx][byte_idx] ^= xorbyte;
 
         /* Check that above bitflips have been reversed correctly */
-        CHECK(secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
+        CHECK(secp256k1_schnorrsig_verify(CTX, sig[sig_idx], msg[sig_idx], sizeof(msg[sig_idx]), &pk));
     }
 
     /* Test overflowing s */
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig[0], msg[0], &keypair, NULL));
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], sizeof(msg[0]), &pk));
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig[0], msg[0], &keypair, NULL));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig[0], msg[0], sizeof(msg[0]), &pk));
     memset(&sig[0][32], 0xFF, 32);
-    CHECK(!secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], sizeof(msg[0]), &pk));
+    CHECK(!secp256k1_schnorrsig_verify(CTX, sig[0], msg[0], sizeof(msg[0]), &pk));
 
     /* Test negative s */
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig[0], msg[0], &keypair, NULL));
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], sizeof(msg[0]), &pk));
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig[0], msg[0], &keypair, NULL));
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig[0], msg[0], sizeof(msg[0]), &pk));
     secp256k1_scalar_set_b32(&s, &sig[0][32], NULL);
     secp256k1_scalar_negate(&s, &s);
     secp256k1_scalar_get_b32(&sig[0][32], &s);
-    CHECK(!secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], sizeof(msg[0]), &pk));
+    CHECK(!secp256k1_schnorrsig_verify(CTX, sig[0], msg[0], sizeof(msg[0]), &pk));
 
     /* The empty message can be signed & verified */
-    CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig[0], NULL, 0, &keypair, NULL) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], NULL, 0, &pk) == 1);
+    CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig[0], NULL, 0, &keypair, NULL) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig[0], NULL, 0, &pk) == 1);
 
     {
         /* Test varying message lengths */
@@ -817,16 +920,16 @@ void test_schnorrsig_sign_verify(void) {
         for (i = 0; i < sizeof(msg_large); i += 32) {
             secp256k1_testrand256(&msg_large[i]);
         }
-        CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig[0], msg_large, msglen, &keypair, NULL) == 1);
-        CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg_large, msglen, &pk) == 1);
+        CHECK(secp256k1_schnorrsig_sign_custom(CTX, sig[0], msg_large, msglen, &keypair, NULL) == 1);
+        CHECK(secp256k1_schnorrsig_verify(CTX, sig[0], msg_large, msglen, &pk) == 1);
         /* Verification for a random wrong message length fails */
         msglen = (msglen + (sizeof(msg_large) - 1)) % sizeof(msg_large);
-        CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg_large, msglen, &pk) == 0);
+        CHECK(secp256k1_schnorrsig_verify(CTX, sig[0], msg_large, msglen, &pk) == 0);
     }
 }
 #undef N_SIGS
 
-void test_schnorrsig_taproot(void) {
+static void test_schnorrsig_taproot(void) {
     unsigned char sk[32];
     secp256k1_keypair keypair;
     secp256k1_xonly_pubkey internal_pk;
@@ -840,36 +943,36 @@ void test_schnorrsig_taproot(void) {
 
     /* Create output key */
     secp256k1_testrand256(sk);
-    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &internal_pk, NULL, &keypair) == 1);
+    CHECK(secp256k1_keypair_create(CTX, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &internal_pk, NULL, &keypair) == 1);
     /* In actual taproot the tweak would be hash of internal_pk */
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, tweak, &internal_pk) == 1);
-    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
-    CHECK(secp256k1_keypair_xonly_pub(ctx, &output_pk, &pk_parity, &keypair) == 1);
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, output_pk_bytes, &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, tweak, &internal_pk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(CTX, &keypair, tweak) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(CTX, &output_pk, &pk_parity, &keypair) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, output_pk_bytes, &output_pk) == 1);
 
     /* Key spend */
     secp256k1_testrand256(msg);
-    CHECK(secp256k1_schnorrsig_sign32(ctx, sig, msg, &keypair, NULL) == 1);
+    CHECK(secp256k1_schnorrsig_sign32(CTX, sig, msg, &keypair, NULL) == 1);
     /* Verify key spend */
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &output_pk, output_pk_bytes) == 1);
-    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &output_pk, output_pk_bytes) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, sig, msg, sizeof(msg), &output_pk) == 1);
 
     /* Script spend */
-    CHECK(secp256k1_xonly_pubkey_serialize(ctx, internal_pk_bytes, &internal_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(CTX, internal_pk_bytes, &internal_pk) == 1);
     /* Verify script spend */
-    CHECK(secp256k1_xonly_pubkey_parse(ctx, &internal_pk, internal_pk_bytes) == 1);
-    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk_bytes, pk_parity, &internal_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(CTX, &internal_pk, internal_pk_bytes) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(CTX, output_pk_bytes, pk_parity, &internal_pk, tweak) == 1);
 }
 
-void run_schnorrsig_tests(void) {
+static void run_schnorrsig_tests(void) {
     int i;
     run_nonce_function_bip340_tests();
 
     test_schnorrsig_api();
     test_schnorrsig_sha256_tagged();
     test_schnorrsig_bip_vectors();
-    for (i = 0; i < count; i++) {
+    for (i = 0; i < COUNT; i++) {
         test_schnorrsig_sign();
         test_schnorrsig_sign_verify();
     }

src/precompute_ecmult.c

@@ -7,12 +7,6 @@
 #include <inttypes.h>
 #include <stdio.h>
 
-/* Autotools creates libsecp256k1-config.h, of which ECMULT_WINDOW_SIZE is needed.
-   ifndef guard so downstream users can define their own if they do not use autotools. */
-#if !defined(ECMULT_WINDOW_SIZE)
-#include "libsecp256k1-config.h"
-#endif
-
 #include "../include/secp256k1.h"
 
 #include "assumptions.h"
@@ -62,11 +56,12 @@ static void print_two_tables(FILE *fp, int window_g) {
 int main(void) {
     /* Always compute all tables for window sizes up to 15. */
     int window_g = (ECMULT_WINDOW_SIZE < 15) ? 15 : ECMULT_WINDOW_SIZE;
+    const char outfile[] = "src/precomputed_ecmult.c";
     FILE* fp;
 
-    fp = fopen("src/precomputed_ecmult.c","w");
+    fp = fopen(outfile, "w");
     if (fp == NULL) {
-        fprintf(stderr, "Could not open src/precomputed_ecmult.h for writing!\n");
+        fprintf(stderr, "Could not open %s for writing!\n", outfile);
         return -1;
     }
 
@@ -74,10 +69,6 @@ int main(void) {
     fprintf(fp, "/* This file contains an array secp256k1_pre_g with odd multiples of the base point G and\n");
     fprintf(fp, " * an array secp256k1_pre_g_128 with odd multiples of 2^128*G for accelerating the computation of a*P + b*G.\n");
     fprintf(fp, " */\n");
-    fprintf(fp, "#if defined HAVE_CONFIG_H\n");
-    fprintf(fp, "#    include \"libsecp256k1-config.h\"\n");
-    fprintf(fp, "#endif\n");
-    fprintf(fp, "#include \"../include/secp256k1.h\"\n");
     fprintf(fp, "#include \"group.h\"\n");
     fprintf(fp, "#include \"ecmult.h\"\n");
     fprintf(fp, "#include \"precomputed_ecmult.h\"\n");

src/precompute_ecmult_gen.c

@@ -33,10 +33,6 @@ int main(int argc, char **argv) {
 
     fprintf(fp, "/* This file was automatically generated by precompute_ecmult_gen. */\n");
     fprintf(fp, "/* See ecmult_gen_impl.h for details about the contents of this file. */\n");
-    fprintf(fp, "#if defined HAVE_CONFIG_H\n");
-    fprintf(fp, "#    include \"libsecp256k1-config.h\"\n");
-    fprintf(fp, "#endif\n");
-    fprintf(fp, "#include \"../include/secp256k1.h\"\n");
     fprintf(fp, "#include \"group.h\"\n");
     fprintf(fp, "#include \"ecmult_gen.h\"\n");
     fprintf(fp, "#include \"precomputed_ecmult_gen.h\"\n");