mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-11-29 19:08:12 +00:00
105 lines
3.4 KiB
C
105 lines
3.4 KiB
C
/**
|
|
* Copyright (c) 2019 Anatolii Kurotych
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining
|
|
* a copy of this software and associated documentation files (the "Software"),
|
|
* to deal in the Software without restriction, including without limitation
|
|
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
|
|
* and/or sell copies of the Software, and to permit persons to whom the
|
|
* Software is furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included
|
|
* in all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
|
|
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
|
|
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
|
|
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
|
|
* OTHER DEALINGS IN THE SOFTWARE.
|
|
*/
|
|
|
|
#include "schnorr.h"
|
|
#include "memzero.h"
|
|
|
|
// r = H(Q, kpub, m)
|
|
static void calc_r(const curve_point *Q, const uint8_t pub_key[33],
|
|
const uint8_t *msg, const uint32_t msg_len, bignum256 *r) {
|
|
uint8_t Q_compress[33];
|
|
compress_coords(Q, Q_compress);
|
|
|
|
SHA256_CTX ctx;
|
|
uint8_t digest[SHA256_DIGEST_LENGTH];
|
|
sha256_Init(&ctx);
|
|
sha256_Update(&ctx, Q_compress, 33);
|
|
sha256_Update(&ctx, pub_key, 33);
|
|
sha256_Update(&ctx, msg, msg_len);
|
|
sha256_Final(&ctx, digest);
|
|
bn_read_be(digest, r);
|
|
}
|
|
|
|
// returns 0 if signing succeeded
|
|
int schnorr_sign(const ecdsa_curve *curve, const uint8_t *priv_key,
|
|
const bignum256 *k, const uint8_t *msg, const uint32_t msg_len,
|
|
schnorr_sign_pair *result) {
|
|
bignum256 private_key_scalar;
|
|
bn_read_be(priv_key, &private_key_scalar);
|
|
uint8_t pub_key[33];
|
|
ecdsa_get_public_key33(curve, priv_key, pub_key);
|
|
|
|
/* Q = kG */
|
|
curve_point Q;
|
|
scalar_multiply(curve, k, &Q);
|
|
|
|
/* r = H(Q, kpub, m) */
|
|
calc_r(&Q, pub_key, msg, msg_len, &result->r);
|
|
|
|
/* s = k - r*kpriv mod(order) */
|
|
bignum256 s_temp;
|
|
bn_copy(&result->r, &s_temp);
|
|
bn_multiply(&private_key_scalar, &s_temp, &curve->order);
|
|
bn_subtractmod(k, &s_temp, &result->s, &curve->order);
|
|
memzero(&private_key_scalar, sizeof(private_key_scalar));
|
|
|
|
while (bn_is_less(&curve->order, &result->s)) {
|
|
bn_mod(&result->s, &curve->order);
|
|
}
|
|
|
|
if (bn_is_zero(&result->s) || bn_is_zero(&result->r)) {
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
// returns 0 if verification succeeded
|
|
int schnorr_verify(const ecdsa_curve *curve, const uint8_t *pub_key,
|
|
const uint8_t *msg, const uint32_t msg_len,
|
|
const schnorr_sign_pair *sign) {
|
|
if (msg_len == 0) return 1;
|
|
if (bn_is_zero(&sign->r)) return 2;
|
|
if (bn_is_zero(&sign->s)) return 3;
|
|
if (bn_is_less(&curve->order, &sign->r)) return 4;
|
|
if (bn_is_less(&curve->order, &sign->s)) return 5;
|
|
|
|
curve_point pub_key_point;
|
|
if (!ecdsa_read_pubkey(curve, pub_key, &pub_key_point)) {
|
|
return 6;
|
|
}
|
|
|
|
// Compute Q = sG + r*kpub
|
|
curve_point sG, Q;
|
|
scalar_multiply(curve, &sign->s, &sG);
|
|
point_multiply(curve, &sign->r, &pub_key_point, &Q);
|
|
point_add(curve, &sG, &Q);
|
|
|
|
/* r = H(Q, kpub, m) */
|
|
bignum256 r;
|
|
calc_r(&Q, pub_key, msg, msg_len, &r);
|
|
|
|
if (bn_is_equal(&r, &sign->r)) return 0; // success
|
|
|
|
return 10;
|
|
}
|