initial addition of essential crypto, encoders, workflows and LLM instructions

pkg/crypto/ec/modnscalar.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2013-2021 The btcsuite developers
+// Copyright (c) 2015-2021 The Decred developers
+
+package btcec
+
+import (
+	"next.orly.dev/pkg/crypto/ec/secp256k1"
+)
+
+// ModNScalar implements optimized 256-bit constant-time fixed-precision
+// arithmetic over the secp256k1 group order. This means all arithmetic is
+// performed modulo:
+//
+//	0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
+//
+// It only implements the arithmetic needed for elliptic curve operations,
+// however, the operations that are not implemented can typically be worked
+// around if absolutely needed.  For example, subtraction can be performed by
+// adding the negation.
+//
+// Should it be absolutely necessary, conversion to the standard library
+// math/big.Int can be accomplished by using the Bytes method, slicing the
+// resulting fixed-size array, and feeding it to big.Int.SetBytes.  However,
+// that should typically be avoided when possible as conversion to big.Ints
+// requires allocations, is not constant time, and is slower when working modulo
+// the group order.
+type ModNScalar = secp256k1.ModNScalar
+
+// NonceRFC6979 generates a nonce deterministically according to RFC 6979 using
+// HMAC-SHA256 for the hashing function.  It takes a 32-byte hash as an input
+// and returns a 32-byte nonce to be used for deterministic signing.  The extra
+// and version arguments are optional, but allow additional data to be added to
+// the input of the HMAC.  When provided, the extra data must be 32-bytes and
+// version must be 16 bytes or they will be ignored.
+//
+// Finally, the extraIterations parameter provides a method to produce a stream
+// of deterministic nonces to ensure the signing code is able to produce a nonce
+// that results in a valid signature in the extremely unlikely event the
+// original nonce produced results in an invalid signature (e.g. R == 0).
+// Signing code should start with 0 and increment it if necessary.
+func NonceRFC6979(
+	privKey []byte, hash []byte, extra []byte, version []byte,
+	extraIterations uint32,
+) *ModNScalar {
+
+	return secp256k1.NonceRFC6979(
+		privKey, hash, extra, version,
+		extraIterations,
+	)
+}