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bitcoin-bitcoin-core/src/secp256k1.c
Pieter Wuille 23cfa914d2 Introduce secp256k1_pubkey_t type
2015-07-26 15:59:07 +02:00

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/**********************************************************************
* Copyright (c) 2013-2015 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#define SECP256K1_BUILD (1)
#include "include/secp256k1.h"
#include "util.h"
#include "num_impl.h"
#include "field_impl.h"
#include "scalar_impl.h"
#include "group_impl.h"
#include "ecmult_impl.h"
#include "ecmult_gen_impl.h"
#include "ecdsa_impl.h"
#include "eckey_impl.h"
#include "hash_impl.h"
struct secp256k1_context_struct {
secp256k1_ecmult_context_t ecmult_ctx;
secp256k1_ecmult_gen_context_t ecmult_gen_ctx;
};
secp256k1_context_t* secp256k1_context_create(int flags) {
secp256k1_context_t* ret = (secp256k1_context_t*)checked_malloc(sizeof(secp256k1_context_t));
secp256k1_ecmult_context_init(&ret->ecmult_ctx);
secp256k1_ecmult_gen_context_init(&ret->ecmult_gen_ctx);
if (flags & SECP256K1_CONTEXT_SIGN) {
secp256k1_ecmult_gen_context_build(&ret->ecmult_gen_ctx);
}
if (flags & SECP256K1_CONTEXT_VERIFY) {
secp256k1_ecmult_context_build(&ret->ecmult_ctx);
}
return ret;
}
secp256k1_context_t* secp256k1_context_clone(const secp256k1_context_t* ctx) {
secp256k1_context_t* ret = (secp256k1_context_t*)checked_malloc(sizeof(secp256k1_context_t));
secp256k1_ecmult_context_clone(&ret->ecmult_ctx, &ctx->ecmult_ctx);
secp256k1_ecmult_gen_context_clone(&ret->ecmult_gen_ctx, &ctx->ecmult_gen_ctx);
return ret;
}
void secp256k1_context_destroy(secp256k1_context_t* ctx) {
secp256k1_ecmult_context_clear(&ctx->ecmult_ctx);
secp256k1_ecmult_gen_context_clear(&ctx->ecmult_gen_ctx);
free(ctx);
}
static void secp256k1_pubkey_load(secp256k1_ge_t* ge, const secp256k1_pubkey_t* pubkey) {
if (sizeof(secp256k1_ge_storage_t) == 64) {
/* When the secp256k1_ge_storage_t type is exactly 64 byte, use its
* representation inside secp256k1_pubkey_t, as conversion is very fast.
* Note that secp256k1_pubkey_save must use the same representation. */
secp256k1_ge_storage_t s;
memcpy(&s, &pubkey->data[0], 64);
secp256k1_ge_from_storage(ge, &s);
DEBUG_CHECK(!secp256k1_fe_is_zero(&ge->x));
} else {
/* Otherwise, fall back to 32-byte big endian for X and Y. */
secp256k1_fe_t x, y;
secp256k1_fe_set_b32(&x, pubkey->data);
DEBUG_CHECK(!secp256k1_fe_is_zero(&x));
secp256k1_fe_set_b32(&y, pubkey->data + 32);
secp256k1_ge_set_xy(ge, &x, &y);
}
}
static void secp256k1_pubkey_save(secp256k1_pubkey_t* pubkey, secp256k1_ge_t* ge) {
if (sizeof(secp256k1_ge_storage_t) == 64) {
secp256k1_ge_storage_t s;
secp256k1_ge_to_storage(&s, ge);
memcpy(&pubkey->data[0], &s, 64);
} else {
VERIFY_CHECK(!secp256k1_ge_is_infinity(ge));
secp256k1_fe_normalize_var(&ge->x);
secp256k1_fe_normalize_var(&ge->y);
secp256k1_fe_get_b32(pubkey->data, &ge->x);
secp256k1_fe_get_b32(pubkey->data + 32, &ge->y);
}
}
int secp256k1_ec_pubkey_parse(const secp256k1_context_t* ctx, secp256k1_pubkey_t* pubkey, const unsigned char *input, int inputlen) {
secp256k1_ge_t Q;
(void)ctx;
if (!secp256k1_eckey_pubkey_parse(&Q, input, inputlen)) {
memset(pubkey, 0, sizeof(*pubkey));
return 0;
}
secp256k1_pubkey_save(pubkey, &Q);
secp256k1_ge_clear(&Q);
return 1;
}
int secp256k1_ec_pubkey_serialize(const secp256k1_context_t* ctx, unsigned char *output, int *outputlen, const secp256k1_pubkey_t* pubkey, int compressed) {
secp256k1_ge_t Q;
(void)ctx;
secp256k1_pubkey_load(&Q, pubkey);
return secp256k1_eckey_pubkey_serialize(&Q, output, outputlen, compressed);
}
int secp256k1_ecdsa_verify(const secp256k1_context_t* ctx, const unsigned char *msg32, const unsigned char *sig, int siglen, const secp256k1_pubkey_t *pubkey) {
secp256k1_ge_t q;
secp256k1_ecdsa_sig_t s;
secp256k1_scalar_t m;
int ret = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
DEBUG_CHECK(msg32 != NULL);
DEBUG_CHECK(sig != NULL);
DEBUG_CHECK(pubkey != NULL);
secp256k1_scalar_set_b32(&m, msg32, NULL);
secp256k1_pubkey_load(&q, pubkey);
if (secp256k1_ecdsa_sig_parse(&s, sig, siglen)) {
if (secp256k1_ecdsa_sig_verify(&ctx->ecmult_ctx, &s, &q, &m)) {
/* success is 1, all other values are fail */
ret = 1;
}
}
return ret;
}
static int nonce_function_rfc6979(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, unsigned int counter, const void *data) {
unsigned char keydata[96];
secp256k1_rfc6979_hmac_sha256_t rng;
unsigned int i;
/* We feed a byte array to the PRNG as input, consisting of:
* - the private key (32 bytes) and message (32 bytes), see RFC 6979 3.2d.
* - optionally 32 extra bytes of data, see RFC 6979 3.6 Additional Data.
*/
memcpy(keydata, key32, 32);
memcpy(keydata + 32, msg32, 32);
if (data != NULL) {
memcpy(keydata + 64, data, 32);
}
secp256k1_rfc6979_hmac_sha256_initialize(&rng, keydata, data != NULL ? 96 : 64);
memset(keydata, 0, sizeof(keydata));
for (i = 0; i <= counter; i++) {
secp256k1_rfc6979_hmac_sha256_generate(&rng, nonce32, 32);
}
secp256k1_rfc6979_hmac_sha256_finalize(&rng);
return 1;
}
const secp256k1_nonce_function_t secp256k1_nonce_function_rfc6979 = nonce_function_rfc6979;
const secp256k1_nonce_function_t secp256k1_nonce_function_default = nonce_function_rfc6979;
int secp256k1_ecdsa_sign(const secp256k1_context_t* ctx, const unsigned char *msg32, unsigned char *signature, int *signaturelen, const unsigned char *seckey, secp256k1_nonce_function_t noncefp, const void* noncedata) {
secp256k1_ecdsa_sig_t sig;
secp256k1_scalar_t sec, non, msg;
int ret = 0;
int overflow = 0;
unsigned int count = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
DEBUG_CHECK(msg32 != NULL);
DEBUG_CHECK(signature != NULL);
DEBUG_CHECK(signaturelen != NULL);
DEBUG_CHECK(seckey != NULL);
if (noncefp == NULL) {
noncefp = secp256k1_nonce_function_default;
}
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
/* Fail if the secret key is invalid. */
if (!overflow && !secp256k1_scalar_is_zero(&sec)) {
secp256k1_scalar_set_b32(&msg, msg32, NULL);
while (1) {
unsigned char nonce32[32];
ret = noncefp(nonce32, msg32, seckey, count, noncedata);
if (!ret) {
break;
}
secp256k1_scalar_set_b32(&non, nonce32, &overflow);
memset(nonce32, 0, 32);
if (!secp256k1_scalar_is_zero(&non) && !overflow) {
if (secp256k1_ecdsa_sig_sign(&ctx->ecmult_gen_ctx, &sig, &sec, &msg, &non, NULL)) {
break;
}
}
count++;
}
if (ret) {
ret = secp256k1_ecdsa_sig_serialize(signature, signaturelen, &sig);
}
secp256k1_scalar_clear(&msg);
secp256k1_scalar_clear(&non);
secp256k1_scalar_clear(&sec);
}
if (!ret) {
*signaturelen = 0;
}
return ret;
}
int secp256k1_ecdsa_sign_compact(const secp256k1_context_t* ctx, const unsigned char *msg32, unsigned char *sig64, const unsigned char *seckey, secp256k1_nonce_function_t noncefp, const void* noncedata, int *recid) {
secp256k1_ecdsa_sig_t sig;
secp256k1_scalar_t sec, non, msg;
int ret = 0;
int overflow = 0;
unsigned int count = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
DEBUG_CHECK(msg32 != NULL);
DEBUG_CHECK(sig64 != NULL);
DEBUG_CHECK(seckey != NULL);
if (noncefp == NULL) {
noncefp = secp256k1_nonce_function_default;
}
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
/* Fail if the secret key is invalid. */
if (!overflow && !secp256k1_scalar_is_zero(&sec)) {
secp256k1_scalar_set_b32(&msg, msg32, NULL);
while (1) {
unsigned char nonce32[32];
ret = noncefp(nonce32, msg32, seckey, count, noncedata);
if (!ret) {
break;
}
secp256k1_scalar_set_b32(&non, nonce32, &overflow);
memset(nonce32, 0, 32);
if (!secp256k1_scalar_is_zero(&non) && !overflow) {
if (secp256k1_ecdsa_sig_sign(&ctx->ecmult_gen_ctx, &sig, &sec, &msg, &non, recid)) {
break;
}
}
count++;
}
if (ret) {
secp256k1_scalar_get_b32(sig64, &sig.r);
secp256k1_scalar_get_b32(sig64 + 32, &sig.s);
}
secp256k1_scalar_clear(&msg);
secp256k1_scalar_clear(&non);
secp256k1_scalar_clear(&sec);
}
if (!ret) {
memset(sig64, 0, 64);
}
return ret;
}
int secp256k1_ecdsa_recover_compact(const secp256k1_context_t* ctx, const unsigned char *msg32, const unsigned char *sig64, secp256k1_pubkey_t *pubkey, int recid) {
secp256k1_ge_t q;
secp256k1_ecdsa_sig_t sig;
secp256k1_scalar_t m;
int ret = 0;
int overflow = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
DEBUG_CHECK(msg32 != NULL);
DEBUG_CHECK(sig64 != NULL);
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(recid >= 0 && recid <= 3);
secp256k1_scalar_set_b32(&sig.r, sig64, &overflow);
if (!overflow) {
secp256k1_scalar_set_b32(&sig.s, sig64 + 32, &overflow);
if (!overflow) {
secp256k1_scalar_set_b32(&m, msg32, NULL);
ret = secp256k1_ecdsa_sig_recover(&ctx->ecmult_ctx, &sig, &q, &m, recid);
if (ret) {
secp256k1_pubkey_save(pubkey, &q);
} else {
memset(pubkey, 0, sizeof(*pubkey));
}
}
}
return ret;
}
int secp256k1_ec_seckey_verify(const secp256k1_context_t* ctx, const unsigned char *seckey) {
secp256k1_scalar_t sec;
int ret;
int overflow;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(seckey != NULL);
(void)ctx;
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
ret = !secp256k1_scalar_is_zero(&sec) && !overflow;
secp256k1_scalar_clear(&sec);
return ret;
}
int secp256k1_ec_pubkey_create(const secp256k1_context_t* ctx, secp256k1_pubkey_t *pubkey, const unsigned char *seckey) {
secp256k1_gej_t pj;
secp256k1_ge_t p;
secp256k1_scalar_t sec;
int overflow;
int ret = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(seckey != NULL);
secp256k1_scalar_set_b32(&sec, seckey, &overflow);
ret = !overflow & !secp256k1_scalar_is_zero(&sec);
secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pj, &sec);
secp256k1_ge_set_gej(&p, &pj);
secp256k1_pubkey_save(pubkey, &p);
secp256k1_scalar_clear(&sec);
if (!ret) {
memset(pubkey, 0, sizeof(*pubkey));
}
return ret;
}
int secp256k1_ec_privkey_tweak_add(const secp256k1_context_t* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar_t term;
secp256k1_scalar_t sec;
int ret = 0;
int overflow = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(tweak != NULL);
(void)ctx;
secp256k1_scalar_set_b32(&term, tweak, &overflow);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
ret = secp256k1_eckey_privkey_tweak_add(&sec, &term) && !overflow;
if (ret) {
secp256k1_scalar_get_b32(seckey, &sec);
}
secp256k1_scalar_clear(&sec);
secp256k1_scalar_clear(&term);
return ret;
}
int secp256k1_ec_pubkey_tweak_add(const secp256k1_context_t* ctx, secp256k1_pubkey_t *pubkey, const unsigned char *tweak) {
secp256k1_ge_t p;
secp256k1_scalar_t term;
int ret = 0;
int overflow = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(tweak != NULL);
secp256k1_scalar_set_b32(&term, tweak, &overflow);
secp256k1_pubkey_load(&p, pubkey);
if (!overflow) {
ret = secp256k1_eckey_pubkey_tweak_add(&ctx->ecmult_ctx, &p, &term);
if (ret) {
secp256k1_pubkey_save(pubkey, &p);
} else {
memset(pubkey, 0, sizeof(*pubkey));
}
}
return ret;
}
int secp256k1_ec_privkey_tweak_mul(const secp256k1_context_t* ctx, unsigned char *seckey, const unsigned char *tweak) {
secp256k1_scalar_t factor;
secp256k1_scalar_t sec;
int ret = 0;
int overflow = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(tweak != NULL);
(void)ctx;
secp256k1_scalar_set_b32(&factor, tweak, &overflow);
secp256k1_scalar_set_b32(&sec, seckey, NULL);
ret = secp256k1_eckey_privkey_tweak_mul(&sec, &factor) && !overflow;
if (ret) {
secp256k1_scalar_get_b32(seckey, &sec);
}
secp256k1_scalar_clear(&sec);
secp256k1_scalar_clear(&factor);
return ret;
}
int secp256k1_ec_pubkey_tweak_mul(const secp256k1_context_t* ctx, secp256k1_pubkey_t *pubkey, const unsigned char *tweak) {
secp256k1_ge_t p;
secp256k1_scalar_t factor;
int ret = 0;
int overflow = 0;
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
DEBUG_CHECK(pubkey != NULL);
DEBUG_CHECK(tweak != NULL);
secp256k1_scalar_set_b32(&factor, tweak, &overflow);
secp256k1_pubkey_load(&p, pubkey);
if (!overflow) {
ret = secp256k1_eckey_pubkey_tweak_mul(&ctx->ecmult_ctx, &p, &factor);
if (ret) {
secp256k1_pubkey_save(pubkey, &p);
} else {
memset(pubkey, 0, sizeof(*pubkey));
}
}
return ret;
}
int secp256k1_ec_privkey_export(const secp256k1_context_t* ctx, const unsigned char *seckey, unsigned char *privkey, int *privkeylen, int compressed) {
secp256k1_scalar_t key;
int ret = 0;
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(privkey != NULL);
DEBUG_CHECK(privkeylen != NULL);
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
secp256k1_scalar_set_b32(&key, seckey, NULL);
ret = secp256k1_eckey_privkey_serialize(&ctx->ecmult_gen_ctx, privkey, privkeylen, &key, compressed);
secp256k1_scalar_clear(&key);
return ret;
}
int secp256k1_ec_privkey_import(const secp256k1_context_t* ctx, unsigned char *seckey, const unsigned char *privkey, int privkeylen) {
secp256k1_scalar_t key;
int ret = 0;
DEBUG_CHECK(seckey != NULL);
DEBUG_CHECK(privkey != NULL);
(void)ctx;
ret = secp256k1_eckey_privkey_parse(&key, privkey, privkeylen);
if (ret) {
secp256k1_scalar_get_b32(seckey, &key);
}
secp256k1_scalar_clear(&key);
return ret;
}
int secp256k1_context_randomize(secp256k1_context_t* ctx, const unsigned char *seed32) {
DEBUG_CHECK(ctx != NULL);
DEBUG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
secp256k1_ecmult_gen_blind(&ctx->ecmult_gen_ctx, seed32);
return 1;
}
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