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Add _prefix and _bip324 ellswift_xdh hash functions

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This commit is contained in:
Pieter Wuille
2023-05-05 04:37:30 -04:00
parent 9695deb351
commit df633cdeba
3 changed files with 158 additions and 8 deletions
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15
include/secp256k1_ellswift.h
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@@ -8,7 +8,7 @@ extern "C" {
#endif
/* This module provides an implementation of ElligatorSwift as well as a
* version of x-only ECDH using it.
* 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
@@ -67,6 +67,19 @@ typedef int (*secp256k1_ellswift_xdh_hash_function)(
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_VAR 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_VAR 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.