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schnorrsig: add extra parameter struct for sign_custom

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This simplifies the interface of sign_custom and allows adding more parameters
later in a backward compatible way.
This commit is contained in:
Jonas Nick
2020-11-02 14:41:25 +00:00
parent a0c3fc177f
commit d8d806aaf3
4 changed files with 75 additions and 20 deletions
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25
src/modules/schnorrsig/main_impl.h
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@@ -120,11 +120,7 @@ static void secp256k1_schnorrsig_challenge(secp256k1_scalar* e, const unsigned c
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, unsigned char *aux_rand32) {
return secp256k1_schnorrsig_sign_custom(ctx, sig64, msg32, 32, keypair, NULL, aux_rand32);
}
int secp256k1_schnorrsig_sign_custom(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg, size_t msglen, const secp256k1_keypair *keypair, secp256k1_nonce_function_hardened noncefp, void *ndata) {
int secp256k1_schnorrsig_sign_internal(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg, size_t msglen, const secp256k1_keypair *keypair, secp256k1_nonce_function_hardened noncefp, void *ndata) {
secp256k1_scalar sk;
secp256k1_scalar e;
secp256k1_scalar k;
@@ -187,6 +183,25 @@ int secp256k1_schnorrsig_sign_custom(const secp256k1_context* ctx, unsigned char
return ret;
}
int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg32, const secp256k1_keypair *keypair, unsigned char *aux_rand32) {
return secp256k1_schnorrsig_sign_internal(ctx, sig64, msg32, 32, keypair, secp256k1_nonce_function_bip340, aux_rand32);
}
int secp256k1_schnorrsig_sign_custom(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg, size_t msglen, const secp256k1_keypair *keypair, secp256k1_schnorrsig_extraparams *extraparams) {
secp256k1_nonce_function_hardened noncefp = NULL;
void *ndata = NULL;
VERIFY_CHECK(ctx != NULL);
if (extraparams != NULL) {
ARG_CHECK(secp256k1_memcmp_var(extraparams->magic,
SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC,
sizeof(extraparams->magic)) == 0);
noncefp = extraparams->noncefp;
ndata = extraparams->ndata;
}
return secp256k1_schnorrsig_sign_internal(ctx, sig64, msg, msglen, keypair, noncefp, ndata);
}
int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned char *sig64, const unsigned char *msg, size_t msglen, const secp256k1_xonly_pubkey *pubkey) {
secp256k1_scalar s;
secp256k1_scalar e;

6
src/modules/schnorrsig/tests_exhaustive_impl.h
View File

@@ -141,6 +141,8 @@ static void test_exhaustive_schnorrsig_verify(const secp256k1_context *ctx, cons
static void test_exhaustive_schnorrsig_sign(const secp256k1_context *ctx, unsigned char (*xonly_pubkey_bytes)[32], const secp256k1_keypair* keypairs, const int* parities) {
int d, k;
uint64_t iter = 0;
secp256k1_schnorrsig_extraparams extraparams = SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT;
/* Loop over keys. */
for (d = 1; d < EXHAUSTIVE_TEST_ORDER; ++d) {
int actual_d = d;
@@ -153,6 +155,8 @@ static void test_exhaustive_schnorrsig_sign(const secp256k1_context *ctx, unsign
unsigned char sig64[64];
int actual_k = k;
if (skip_section(&iter)) continue;
extraparams.noncefp = secp256k1_hardened_nonce_function_smallint;
extraparams.ndata = &k;
if (parities[k - 1]) actual_k = EXHAUSTIVE_TEST_ORDER - k;
/* Generate random messages until all challenges have been tried. */
while (e_count_done < EXHAUSTIVE_TEST_ORDER) {
@@ -165,7 +169,7 @@ static void test_exhaustive_schnorrsig_sign(const secp256k1_context *ctx, unsign
unsigned char expected_s_bytes[32];
secp256k1_scalar_get_b32(expected_s_bytes, &expected_s);
/* Invoke the real function to construct a signature. */
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig64, msg32, sizeof(msg32), &keypairs[d - 1], secp256k1_hardened_nonce_function_smallint, &k));
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig64, msg32, sizeof(msg32), &keypairs[d - 1], &extraparams));
/* The first 32 bytes must match the xonly pubkey for the specified k. */
CHECK(secp256k1_memcmp_var(sig64, xonly_pubkey_bytes[k - 1], 32) == 0);
/* The last 32 bytes must match the expected s value. */

18
src/modules/schnorrsig/tests_impl.h
View File

@@ -690,24 +690,34 @@ static int nonce_function_overflowing(unsigned char *nonce32, const unsigned cha
void test_schnorrsig_sign(void) {
unsigned char sk[32];
secp256k1_xonly_pubkey pk;
secp256k1_keypair keypair;
const unsigned char msg[32] = "this is a msg for a schnorrsig..";
unsigned char sig[64];
unsigned char zeros64[64] = { 0 };
secp256k1_schnorrsig_extraparams extraparams = SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT;
secp256k1_testrand256(sk);
CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, NULL) == 1);
CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, sizeof(msg), &pk));
/* 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));
memset(sig, 1, sizeof(sig));
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, nonce_function_failing, NULL) == 0);
extraparams.noncefp = nonce_function_failing;
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));
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, nonce_function_0, NULL) == 0);
extraparams.noncefp = nonce_function_0;
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, &extraparams) == 0);
CHECK(secp256k1_memcmp_var(sig, zeros64, sizeof(sig)) == 0);
CHECK(secp256k1_schnorrsig_sign_custom(ctx, sig, msg, sizeof(msg), &keypair, nonce_function_overflowing, NULL) == 1);
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));
}
#define N_SIGS 3