diff options
Diffstat (limited to 'src/secp256k1/src/modules/schnorrsig/main_impl.h')
-rw-r--r-- | src/secp256k1/src/modules/schnorrsig/main_impl.h | 39 |
1 files changed, 20 insertions, 19 deletions
diff --git a/src/secp256k1/src/modules/schnorrsig/main_impl.h b/src/secp256k1/src/modules/schnorrsig/main_impl.h index a0218f881a..b0d8481f9b 100644 --- a/src/secp256k1/src/modules/schnorrsig/main_impl.h +++ b/src/secp256k1/src/modules/schnorrsig/main_impl.h @@ -68,7 +68,7 @@ static int nonce_function_bip340(unsigned char *nonce32, const unsigned char *ms /* Tag the hash with algo16 which is important to avoid nonce reuse across * algorithms. If this nonce function is used in BIP-340 signing as defined * in the spec, an optimized tagging implementation is used. */ - if (memcmp(algo16, bip340_algo16, 16) == 0) { + if (secp256k1_memcmp_var(algo16, bip340_algo16, 16) == 0) { secp256k1_nonce_function_bip340_sha256_tagged(&sha); } else { int algo16_len = 16; @@ -108,6 +108,22 @@ static void secp256k1_schnorrsig_sha256_tagged(secp256k1_sha256 *sha) { sha->bytes = 64; } +static void secp256k1_schnorrsig_challenge(secp256k1_scalar* e, const unsigned char *r32, const unsigned char *msg32, const unsigned char *pubkey32) +{ + unsigned char buf[32]; + secp256k1_sha256 sha; + + /* tagged hash(r.x, pk.x, msg32) */ + secp256k1_schnorrsig_sha256_tagged(&sha); + secp256k1_sha256_write(&sha, r32, 32); + secp256k1_sha256_write(&sha, pubkey32, 32); + secp256k1_sha256_write(&sha, msg32, 32); + secp256k1_sha256_finalize(&sha, buf); + /* Set scalar e to the challenge hash modulo the curve order as per + * BIP340. */ + secp256k1_scalar_set_b32(e, buf, NULL); +} + int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg32, const secp256k1_keypair *keypair, secp256k1_nonce_function_hardened noncefp, void *ndata) { secp256k1_scalar sk; secp256k1_scalar e; @@ -115,7 +131,6 @@ int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, unsigned char *sig64 secp256k1_gej rj; secp256k1_ge pk; secp256k1_ge r; - secp256k1_sha256 sha; unsigned char buf[32] = { 0 }; unsigned char pk_buf[32]; unsigned char seckey[32]; @@ -159,16 +174,7 @@ int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, unsigned char *sig64 secp256k1_fe_normalize_var(&r.x); secp256k1_fe_get_b32(&sig64[0], &r.x); - /* tagged hash(r.x, pk.x, msg32) */ - secp256k1_schnorrsig_sha256_tagged(&sha); - secp256k1_sha256_write(&sha, &sig64[0], 32); - secp256k1_sha256_write(&sha, pk_buf, sizeof(pk_buf)); - secp256k1_sha256_write(&sha, msg32, 32); - secp256k1_sha256_finalize(&sha, buf); - - /* Set scalar e to the challenge hash modulo the curve order as per - * BIP340. */ - secp256k1_scalar_set_b32(&e, buf, NULL); + secp256k1_schnorrsig_challenge(&e, &sig64[0], msg32, pk_buf); secp256k1_scalar_mul(&e, &e, &sk); secp256k1_scalar_add(&e, &e, &k); secp256k1_scalar_get_b32(&sig64[32], &e); @@ -189,7 +195,6 @@ int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned cha secp256k1_gej pkj; secp256k1_fe rx; secp256k1_ge r; - secp256k1_sha256 sha; unsigned char buf[32]; int overflow; @@ -212,13 +217,9 @@ int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned cha return 0; } - secp256k1_schnorrsig_sha256_tagged(&sha); - secp256k1_sha256_write(&sha, &sig64[0], 32); + /* Compute e. */ secp256k1_fe_get_b32(buf, &pk.x); - secp256k1_sha256_write(&sha, buf, sizeof(buf)); - secp256k1_sha256_write(&sha, msg32, 32); - secp256k1_sha256_finalize(&sha, buf); - secp256k1_scalar_set_b32(&e, buf, NULL); + secp256k1_schnorrsig_challenge(&e, &sig64[0], msg32, buf); /* Compute rj = s*G + (-e)*pkj */ secp256k1_scalar_negate(&e, &e); |