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/**********************************************************************
* Copyright (c) 2014-2015 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef SECP256K1_MODULE_SCHNORR_MAIN
#define SECP256K1_MODULE_SCHNORR_MAIN
#include "modules/schnorr/schnorr_impl.h"
static void secp256k1_schnorr_msghash_sha256(unsigned char *h32, const unsigned char *r32, const unsigned char *msg32) {
secp256k1_sha256_t sha;
secp256k1_sha256_initialize(&sha);
secp256k1_sha256_write(&sha, r32, 32);
secp256k1_sha256_write(&sha, msg32, 32);
secp256k1_sha256_finalize(&sha, h32);
}
static const unsigned char secp256k1_schnorr_algo16[16] = "Schnorr+SHA256 ";
int secp256k1_schnorr_sign(const secp256k1_context_t* ctx, unsigned char *sig64, const unsigned char *msg32, const unsigned char *seckey, secp256k1_nonce_function_t noncefp, const void* noncedata) {
secp256k1_scalar_t sec, non;
int ret = 0;
int overflow = 0;
unsigned int count = 0;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(sig64 != NULL);
ARG_CHECK(seckey != NULL);
if (noncefp == NULL) {
noncefp = secp256k1_nonce_function_default;
}
secp256k1_scalar_set_b32(&sec, seckey, NULL);
while (1) {
unsigned char nonce32[32];
ret = noncefp(nonce32, msg32, seckey, secp256k1_schnorr_algo16, (void*)noncedata, count);
if (!ret) {
break;
}
secp256k1_scalar_set_b32(&non, nonce32, &overflow);
memset(nonce32, 0, 32);
if (!secp256k1_scalar_is_zero(&non) && !overflow) {
if (secp256k1_schnorr_sig_sign(&ctx->ecmult_gen_ctx, sig64, &sec, &non, NULL, secp256k1_schnorr_msghash_sha256, msg32)) {
break;
}
}
count++;
}
if (!ret) {
memset(sig64, 0, 64);
}
secp256k1_scalar_clear(&non);
secp256k1_scalar_clear(&sec);
return ret;
}
int secp256k1_schnorr_verify(const secp256k1_context_t* ctx, const unsigned char *sig64, const unsigned char *msg32, const secp256k1_pubkey_t *pubkey) {
secp256k1_ge_t q;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(sig64 != NULL);
ARG_CHECK(pubkey != NULL);
secp256k1_pubkey_load(ctx, &q, pubkey);
return secp256k1_schnorr_sig_verify(&ctx->ecmult_ctx, sig64, &q, secp256k1_schnorr_msghash_sha256, msg32);
}
int secp256k1_schnorr_recover(const secp256k1_context_t* ctx, secp256k1_pubkey_t *pubkey, const unsigned char *sig64, const unsigned char *msg32) {
secp256k1_ge_t q;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(sig64 != NULL);
ARG_CHECK(pubkey != NULL);
if (secp256k1_schnorr_sig_recover(&ctx->ecmult_ctx, sig64, &q, secp256k1_schnorr_msghash_sha256, msg32)) {
secp256k1_pubkey_save(pubkey, &q);
return 1;
} else {
memset(pubkey, 0, sizeof(*pubkey));
return 0;
}
}
int secp256k1_schnorr_generate_nonce_pair(const secp256k1_context_t* ctx, secp256k1_pubkey_t *pubnonce, unsigned char *privnonce32, const unsigned char *sec32, const unsigned char *msg32, secp256k1_nonce_function_t noncefp, const void* noncedata) {
int count = 0;
int ret = 1;
secp256k1_gej_t Qj;
secp256k1_ge_t Q;
secp256k1_scalar_t sec;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(sec32 != NULL);
ARG_CHECK(pubnonce != NULL);
ARG_CHECK(privnonce32 != NULL);
if (noncefp == NULL) {
noncefp = secp256k1_nonce_function_default;
}
do {
int overflow;
ret = noncefp(privnonce32, sec32, msg32, secp256k1_schnorr_algo16, (void*)noncedata, count++);
if (!ret) {
break;
}
secp256k1_scalar_set_b32(&sec, privnonce32, &overflow);
if (overflow || secp256k1_scalar_is_zero(&sec)) {
continue;
}
secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &Qj, &sec);
secp256k1_ge_set_gej(&Q, &Qj);
secp256k1_pubkey_save(pubnonce, &Q);
break;
} while(1);
secp256k1_scalar_clear(&sec);
if (!ret) {
memset(pubnonce, 0, sizeof(*pubnonce));
}
return ret;
}
int secp256k1_schnorr_partial_sign(const secp256k1_context_t* ctx, unsigned char *sig64, const unsigned char *msg32, const unsigned char *sec32, const secp256k1_pubkey_t *pubnonce_others, const unsigned char *secnonce32) {
int overflow = 0;
secp256k1_scalar_t sec, non;
secp256k1_ge_t pubnon;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(sig64 != NULL);
ARG_CHECK(sec32 != NULL);
ARG_CHECK(secnonce32 != NULL);
ARG_CHECK(pubnonce_others != NULL);
secp256k1_scalar_set_b32(&sec, sec32, &overflow);
if (overflow || secp256k1_scalar_is_zero(&sec)) {
return -1;
}
secp256k1_scalar_set_b32(&non, secnonce32, &overflow);
if (overflow || secp256k1_scalar_is_zero(&non)) {
return -1;
}
secp256k1_pubkey_load(ctx, &pubnon, pubnonce_others);
return secp256k1_schnorr_sig_sign(&ctx->ecmult_gen_ctx, sig64, &sec, &non, &pubnon, secp256k1_schnorr_msghash_sha256, msg32);
}
int secp256k1_schnorr_partial_combine(const secp256k1_context_t* ctx, unsigned char *sig64, const unsigned char * const *sig64sin, int n) {
ARG_CHECK(sig64 != NULL);
ARG_CHECK(n >= 1);
ARG_CHECK(sig64sin != NULL);
return secp256k1_schnorr_sig_combine(sig64, n, sig64sin);
}
#endif