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630 lines
16 KiB
630 lines
16 KiB
/**
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* Copyright (c) 2013-2014 Tomas Dzetkulic
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* Copyright (c) 2013-2014 Pavol Rusnak
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
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* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include "bignum.h"
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#include "rand.h"
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#include "sha2.h"
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#include "ripemd160.h"
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#include "hmac.h"
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#include "ecdsa.h"
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#include "base58.h"
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// Set cp2 = cp1
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void point_copy(const curve_point *cp1, curve_point *cp2)
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{
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memcpy(&(cp2->x), &(cp1->x), sizeof(bignum256));
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memcpy(&(cp2->y), &(cp1->y), sizeof(bignum256));
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}
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// cp2 = cp1 + cp2
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void point_add(const curve_point *cp1, curve_point *cp2)
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{
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int i;
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uint32_t temp;
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bignum256 lambda, inv, xr, yr;
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if (point_is_infinity(cp1)) {
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return;
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}
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if (point_is_infinity(cp2)) {
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point_copy(cp1, cp2);
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return;
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}
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if (point_is_equal(cp1, cp2)) {
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point_double(cp2);
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return;
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}
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if (point_is_negative_of(cp1, cp2)) {
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point_set_infinity(cp2);
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return;
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}
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bn_substract(&(cp2->x), &(cp1->x), &inv);
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bn_inverse(&inv, &prime256k1);
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bn_substract(&(cp2->y), &(cp1->y), &lambda);
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bn_multiply(&inv, &lambda, &prime256k1);
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memcpy(&xr, &lambda, sizeof(bignum256));
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bn_multiply(&xr, &xr, &prime256k1);
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temp = 0;
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for (i = 0; i < 9; i++) {
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temp += xr.val[i] + 3u * prime256k1.val[i] - cp1->x.val[i] - cp2->x.val[i];
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xr.val[i] = temp & 0x3FFFFFFF;
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temp >>= 30;
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}
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bn_fast_mod(&xr, &prime256k1);
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bn_substract(&(cp1->x), &xr, &yr);
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// no need to fast_mod here
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// bn_fast_mod(&yr);
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bn_multiply(&lambda, &yr, &prime256k1);
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bn_substract(&yr, &(cp1->y), &yr);
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bn_fast_mod(&yr, &prime256k1);
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memcpy(&(cp2->x), &xr, sizeof(bignum256));
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memcpy(&(cp2->y), &yr, sizeof(bignum256));
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bn_mod(&(cp2->x), &prime256k1);
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bn_mod(&(cp2->y), &prime256k1);
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}
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// cp = cp + cp
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void point_double(curve_point *cp)
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{
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int i;
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uint32_t temp;
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bignum256 lambda, inverse_y, xr, yr;
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if (point_is_infinity(cp)) {
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return;
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}
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if (bn_is_zero(&(cp->y))) {
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point_set_infinity(cp);
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return;
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}
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memcpy(&inverse_y, &(cp->y), sizeof(bignum256));
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bn_inverse(&inverse_y, &prime256k1);
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memcpy(&lambda, &three_over_two256k1, sizeof(bignum256));
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bn_multiply(&inverse_y, &lambda, &prime256k1);
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bn_multiply(&(cp->x), &lambda, &prime256k1);
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bn_multiply(&(cp->x), &lambda, &prime256k1);
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memcpy(&xr, &lambda, sizeof(bignum256));
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bn_multiply(&xr, &xr, &prime256k1);
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temp = 0;
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for (i = 0; i < 9; i++) {
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temp += xr.val[i] + 3u * prime256k1.val[i] - 2u * cp->x.val[i];
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xr.val[i] = temp & 0x3FFFFFFF;
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temp >>= 30;
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}
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bn_fast_mod(&xr, &prime256k1);
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bn_substract(&(cp->x), &xr, &yr);
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// no need to fast_mod here
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// bn_fast_mod(&yr);
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bn_multiply(&lambda, &yr, &prime256k1);
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bn_substract(&yr, &(cp->y), &yr);
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bn_fast_mod(&yr, &prime256k1);
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memcpy(&(cp->x), &xr, sizeof(bignum256));
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memcpy(&(cp->y), &yr, sizeof(bignum256));
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bn_mod(&(cp->x), &prime256k1);
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bn_mod(&(cp->y), &prime256k1);
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}
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// res = k * p
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void point_multiply(const bignum256 *k, const curve_point *p, curve_point *res)
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{
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int i, j;
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// result is zero
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int is_zero = 1;
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curve_point curr;
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// initial res
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memcpy(&curr, p, sizeof(curve_point));
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for (i = 0; i < 9; i++) {
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for (j = 0; j < 30; j++) {
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if (i == 8 && (k->val[i] >> j) == 0) break;
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if (k->val[i] & (1u << j)) {
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if (is_zero) {
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memcpy(res, &curr, sizeof(curve_point));
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is_zero = 0;
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} else {
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point_add(&curr, res);
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}
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}
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point_double(&curr);
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}
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}
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}
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// set point to internal representation of point at infinity
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void point_set_infinity(curve_point *p)
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{
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bn_zero(&(p->x));
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bn_zero(&(p->y));
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}
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// return true iff p represent point at infinity
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// both coords are zero in internal representation
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int point_is_infinity(const curve_point *p)
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{
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return bn_is_zero(&(p->x)) && bn_is_zero(&(p->y));
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}
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// return true iff both points are equal
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int point_is_equal(const curve_point *p, const curve_point *q)
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{
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return bn_is_equal(&(p->x), &(q->x)) && bn_is_equal(&(p->y), &(q->y));
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}
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// returns true iff p == -q
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// expects p and q be valid points on curve other than point at infinity
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int point_is_negative_of(const curve_point *p, const curve_point *q)
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{
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// if P == (x, y), then -P would be (x, -y) on this curve
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if (!bn_is_equal(&(p->x), &(q->x))) {
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return 0;
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}
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// we shouldn't hit this for a valid point
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if (bn_is_zero(&(p->y))) {
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return 0;
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}
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return !bn_is_equal(&(p->y), &(q->y));
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}
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// res = k * G
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void scalar_multiply(const bignum256 *k, curve_point *res)
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{
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int i;
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// result is zero
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int is_zero = 1;
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curve_point curr;
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// initial res
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memcpy(&curr, &G256k1, sizeof(curve_point));
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for (i = 0; i < 256; i++) {
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if (k->val[i / 30] & (1u << (i % 30))) {
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if (is_zero) {
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#if USE_PRECOMPUTED_CP
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if (i < 255 && (k->val[(i + 1) / 30] & (1u << ((i + 1) % 30)))) {
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memcpy(res, secp256k1_cp2 + i, sizeof(curve_point));
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i++;
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} else {
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memcpy(res, secp256k1_cp + i, sizeof(curve_point));
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}
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#else
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memcpy(res, &curr, sizeof(curve_point));
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#endif
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is_zero = 0;
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} else {
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#if USE_PRECOMPUTED_CP
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if (i < 255 && (k->val[(i + 1) / 30] & (1u << ((i + 1) % 30)))) {
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point_add(secp256k1_cp2 + i, res);
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i++;
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} else {
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point_add(secp256k1_cp + i, res);
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}
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#else
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point_add(&curr, res);
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#endif
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}
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}
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#if ! USE_PRECOMPUTED_CP
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point_double(&curr);
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#endif
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}
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}
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// generate random K for signing
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int generate_k_random(bignum256 *k) {
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int i, j;
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for (j = 0; j < 10000; j++) {
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for (i = 0; i < 8; i++) {
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k->val[i] = random32() & 0x3FFFFFFF;
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}
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k->val[8] = random32() & 0xFFFF;
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// if k is too big or too small, we don't like it
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if ( !bn_is_zero(k) && bn_is_less(k, &order256k1) ) {
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return 0; // good number - no error
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}
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}
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// we generated 10000 numbers, none of them is good -> fail
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return 1;
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}
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// generate K in a deterministic way, according to RFC6979
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// http://tools.ietf.org/html/rfc6979
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int generate_k_rfc6979(bignum256 *secret, const uint8_t *priv_key, const uint8_t *hash)
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{
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int i;
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uint8_t v[32], k[32], bx[2*32], buf[32 + 1 + sizeof(bx)], t[32];
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bignum256 z1;
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memcpy(bx, priv_key, 32);
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bn_read_be(hash, &z1);
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bn_mod(&z1, &order256k1);
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bn_write_be(&z1, bx + 32);
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memset(v, 1, sizeof(v));
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memset(k, 0, sizeof(k));
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memcpy(buf, v, sizeof(v));
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buf[sizeof(v)] = 0x00;
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memcpy(buf + sizeof(v) + 1, bx, 64);
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hmac_sha256(k, sizeof(k), buf, sizeof(buf), k);
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hmac_sha256(k, sizeof(k), v, sizeof(v), v);
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memcpy(buf, v, sizeof(v));
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buf[sizeof(v)] = 0x01;
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memcpy(buf + sizeof(v) + 1, bx, 64);
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hmac_sha256(k, sizeof(k), buf, sizeof(buf), k);
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hmac_sha256(k, sizeof(k), v, sizeof(k), v);
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for (i = 0; i < 10000; i++) {
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hmac_sha256(k, sizeof(k), v, sizeof(v), t);
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bn_read_be(t, secret);
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if ( !bn_is_zero(secret) && bn_is_less(secret, &order256k1) ) {
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return 0; // good number -> no error
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}
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memcpy(buf, v, sizeof(v));
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buf[sizeof(v)] = 0x00;
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hmac_sha256(k, sizeof(k), buf, sizeof(v) + 1, k);
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hmac_sha256(k, sizeof(k), v, sizeof(v), v);
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}
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// we generated 10000 numbers, none of them is good -> fail
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return 1;
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}
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// msg is a data to be signed
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// msg_len is the message length
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int ecdsa_sign(const uint8_t *priv_key, const uint8_t *msg, uint32_t msg_len, uint8_t *sig)
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{
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uint8_t hash[32];
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sha256_Raw(msg, msg_len, hash);
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return ecdsa_sign_digest(priv_key, hash, sig);
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}
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// msg is a data to be signed
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// msg_len is the message length
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int ecdsa_sign_double(const uint8_t *priv_key, const uint8_t *msg, uint32_t msg_len, uint8_t *sig)
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{
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uint8_t hash[32];
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sha256_Raw(msg, msg_len, hash);
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sha256_Raw(hash, 32, hash);
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return ecdsa_sign_digest(priv_key, hash, sig);
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}
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// uses secp256k1 curve
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// priv_key is a 32 byte big endian stored number
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// sig is 64 bytes long array for the signature
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// digest is 32 bytes of digest
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int ecdsa_sign_digest(const uint8_t *priv_key, const uint8_t *digest, uint8_t *sig)
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{
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uint32_t i;
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curve_point R;
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bignum256 k, z;
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bignum256 *da = &R.y;
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bn_read_be(digest, &z);
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#if USE_RFC6979
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// generate K deterministically
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if (generate_k_rfc6979(&k, priv_key, digest) != 0) {
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return 1;
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}
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#else
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// generate random number k
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if (generate_k_random(&k) != 0) {
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return 1;
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}
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#endif
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// compute k*G
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scalar_multiply(&k, &R);
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// r = (rx mod n)
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bn_mod(&R.x, &order256k1);
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// if r is zero, we fail
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if (bn_is_zero(&R.x)) return 2;
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bn_inverse(&k, &order256k1);
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bn_read_be(priv_key, da);
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bn_multiply(&R.x, da, &order256k1);
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for (i = 0; i < 8; i++) {
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da->val[i] += z.val[i];
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da->val[i + 1] += (da->val[i] >> 30);
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da->val[i] &= 0x3FFFFFFF;
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}
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da->val[8] += z.val[8];
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bn_multiply(da, &k, &order256k1);
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bn_mod(&k, &order256k1);
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// if k is zero, we fail
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if (bn_is_zero(&k)) return 3;
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// if S > order/2 => S = -S
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if (bn_is_less(&order256k1_half, &k)) {
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bn_substract_noprime(&order256k1, &k, &k);
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}
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// we are done, R.x and k is the result signature
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bn_write_be(&R.x, sig);
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bn_write_be(&k, sig + 32);
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return 0;
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}
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void ecdsa_get_public_key33(const uint8_t *priv_key, uint8_t *pub_key)
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{
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curve_point R;
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bignum256 k;
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bn_read_be(priv_key, &k);
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// compute k*G
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scalar_multiply(&k, &R);
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pub_key[0] = 0x02 | (R.y.val[0] & 0x01);
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bn_write_be(&R.x, pub_key + 1);
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}
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void ecdsa_get_public_key65(const uint8_t *priv_key, uint8_t *pub_key)
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{
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curve_point R;
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bignum256 k;
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bn_read_be(priv_key, &k);
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// compute k*G
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scalar_multiply(&k, &R);
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pub_key[0] = 0x04;
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bn_write_be(&R.x, pub_key + 1);
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bn_write_be(&R.y, pub_key + 33);
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}
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void ecdsa_get_pubkeyhash(const uint8_t *pub_key, uint8_t *pubkeyhash)
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{
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uint8_t h[32];
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if (pub_key[0] == 0x04) { // uncompressed format
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sha256_Raw(pub_key, 65, h);
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} else if (pub_key[0] == 0x00) { // point at infinity
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sha256_Raw(pub_key, 1, h);
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} else {
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sha256_Raw(pub_key, 33, h); // expecting compressed format
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}
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ripemd160(h, 32, pubkeyhash);
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}
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void ecdsa_get_address_raw(const uint8_t *pub_key, uint8_t version, uint8_t *addr_raw)
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{
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addr_raw[0] = version;
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ecdsa_get_pubkeyhash(pub_key, addr_raw + 1);
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}
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void ecdsa_get_address(const uint8_t *pub_key, uint8_t version, char *addr)
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{
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uint8_t raw[21];
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ecdsa_get_address_raw(pub_key, version, raw);
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base58_encode_check(raw, 21, addr);
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}
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void ecdsa_get_wif(const uint8_t *priv_key, uint8_t version, char *wif)
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{
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uint8_t data[34];
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data[0] = version;
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memcpy(data + 1, priv_key, 32);
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data[33 ] = 0x01;
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base58_encode_check(data, 34, wif);
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}
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int ecdsa_address_decode(const char *addr, uint8_t *out)
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{
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if (!addr) return 0;
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return base58_decode_check(addr, out) == 21;
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}
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void uncompress_coords(uint8_t odd, const bignum256 *x, bignum256 *y)
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{
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// y^2 = x^3 + 0*x + 7
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memcpy(y, x, sizeof(bignum256)); // y is x
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bn_multiply(x, y, &prime256k1); // y is x^2
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bn_multiply(x, y, &prime256k1); // y is x^3
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bn_addmodi(y, 7, &prime256k1); // y is x^3 + 7
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bn_sqrt(y, &prime256k1); // y = sqrt(y)
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if ((odd & 0x01) != (y->val[0] & 1)) {
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bn_substract_noprime(&prime256k1, y, y); // y = -y
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}
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}
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int ecdsa_read_pubkey(const uint8_t *pub_key, curve_point *pub)
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{
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if (pub_key[0] == 0x04) {
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bn_read_be(pub_key + 1, &(pub->x));
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bn_read_be(pub_key + 33, &(pub->y));
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#if USE_PUBKEY_VALIDATE
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return ecdsa_validate_pubkey(pub);
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#else
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return 1;
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#endif
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}
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if (pub_key[0] == 0x02 || pub_key[0] == 0x03) { // compute missing y coords
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bn_read_be(pub_key + 1, &(pub->x));
|
|
uncompress_coords(pub_key[0], &(pub->x), &(pub->y));
|
|
#if USE_PUBKEY_VALIDATE
|
|
return ecdsa_validate_pubkey(pub);
|
|
#else
|
|
return 1;
|
|
#endif
|
|
}
|
|
// error
|
|
return 0;
|
|
}
|
|
|
|
// Verifies that:
|
|
// - pub is not the point at infinity.
|
|
// - pub->x and pub->y are in range [0,p-1].
|
|
// - pub is on the curve.
|
|
// - n*pub is the point at infinity.
|
|
|
|
int ecdsa_validate_pubkey(const curve_point *pub)
|
|
{
|
|
bignum256 y_2, x_3_b;
|
|
curve_point temp;
|
|
|
|
if (point_is_infinity(pub)) {
|
|
return 0;
|
|
}
|
|
|
|
if (!bn_is_less(&(pub->x), &prime256k1) || !bn_is_less(&(pub->y), &prime256k1)) {
|
|
return 0;
|
|
}
|
|
|
|
memcpy(&y_2, &(pub->y), sizeof(bignum256));
|
|
memcpy(&x_3_b, &(pub->x), sizeof(bignum256));
|
|
|
|
// y^2
|
|
bn_multiply(&(pub->y), &y_2, &prime256k1);
|
|
bn_mod(&y_2, &prime256k1);
|
|
|
|
// x^3 + b
|
|
bn_multiply(&(pub->x), &x_3_b, &prime256k1);
|
|
bn_multiply(&(pub->x), &x_3_b, &prime256k1);
|
|
bn_addmodi(&x_3_b, 7, &prime256k1);
|
|
|
|
if (!bn_is_equal(&x_3_b, &y_2)) {
|
|
return 0;
|
|
}
|
|
|
|
point_multiply(&order256k1, pub, &temp);
|
|
|
|
if (!point_is_infinity(&temp)) {
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
// uses secp256k1 curve
|
|
// pub_key - 65 bytes uncompressed key
|
|
// signature - 64 bytes signature
|
|
// msg is a data that was signed
|
|
// msg_len is the message length
|
|
|
|
int ecdsa_verify(const uint8_t *pub_key, const uint8_t *sig, const uint8_t *msg, uint32_t msg_len)
|
|
{
|
|
uint8_t hash[32];
|
|
sha256_Raw(msg, msg_len, hash);
|
|
return ecdsa_verify_digest(pub_key, sig, hash);
|
|
}
|
|
|
|
int ecdsa_verify_double(const uint8_t *pub_key, const uint8_t *sig, const uint8_t *msg, uint32_t msg_len)
|
|
{
|
|
uint8_t hash[32];
|
|
sha256_Raw(msg, msg_len, hash);
|
|
sha256_Raw(hash, 32, hash);
|
|
return ecdsa_verify_digest(pub_key, sig, hash);
|
|
}
|
|
|
|
// returns 0 if verification succeeded
|
|
int ecdsa_verify_digest(const uint8_t *pub_key, const uint8_t *sig, const uint8_t *digest)
|
|
{
|
|
int i, j;
|
|
curve_point pub, res;
|
|
bignum256 r, s, z;
|
|
|
|
if (!ecdsa_read_pubkey(pub_key, &pub)) {
|
|
return 1;
|
|
}
|
|
|
|
bn_read_be(sig, &r);
|
|
bn_read_be(sig + 32, &s);
|
|
|
|
bn_read_be(digest, &z);
|
|
|
|
if (bn_is_zero(&r) || bn_is_zero(&s) ||
|
|
(!bn_is_less(&r, &order256k1)) ||
|
|
(!bn_is_less(&s, &order256k1))) return 2;
|
|
|
|
bn_inverse(&s, &order256k1); // s^-1
|
|
bn_multiply(&s, &z, &order256k1); // z*s^-1
|
|
bn_mod(&z, &order256k1);
|
|
bn_multiply(&r, &s, &order256k1); // r*s^-1
|
|
bn_mod(&s, &order256k1);
|
|
if (bn_is_zero(&z)) {
|
|
// our message hashes to zero
|
|
// I don't expect this to happen any time soon
|
|
return 3;
|
|
} else {
|
|
scalar_multiply(&z, &res);
|
|
}
|
|
|
|
// both pub and res can be infinity, can have y = 0 OR can be equal -> false negative
|
|
for (i = 0; i < 9; i++) {
|
|
for (j = 0; j < 30; j++) {
|
|
if (i == 8 && (s.val[i] >> j) == 0) break;
|
|
if (s.val[i] & (1u << j)) {
|
|
point_add(&pub, &res);
|
|
}
|
|
point_double(&pub);
|
|
}
|
|
}
|
|
|
|
bn_mod(&(res.x), &order256k1);
|
|
|
|
// signature does not match
|
|
if (!bn_is_equal(&res.x, &r)) return 5;
|
|
|
|
// all OK
|
|
return 0;
|
|
}
|
|
|
|
int ecdsa_sig_to_der(const uint8_t *sig, uint8_t *der)
|
|
{
|
|
int i;
|
|
uint8_t *p = der, *len, *len1, *len2;
|
|
*p = 0x30; p++; // sequence
|
|
*p = 0x00; len = p; p++; // len(sequence)
|
|
|
|
*p = 0x02; p++; // integer
|
|
*p = 0x00; len1 = p; p++; // len(integer)
|
|
|
|
// process R
|
|
i = 0;
|
|
while (sig[i] == 0 && i < 32) { i++; } // skip leading zeroes
|
|
if (sig[i] >= 0x80) { // put zero in output if MSB set
|
|
*p = 0x00; p++; *len1 = *len1 + 1;
|
|
}
|
|
while (i < 32) { // copy bytes to output
|
|
*p = sig[i]; p++; *len1 = *len1 + 1; i++;
|
|
}
|
|
|
|
*p = 0x02; p++; // integer
|
|
*p = 0x00; len2 = p; p++; // len(integer)
|
|
|
|
// process S
|
|
i = 32;
|
|
while (sig[i] == 0 && i < 64) { i++; } // skip leading zeroes
|
|
if (sig[i] >= 0x80) { // put zero in output if MSB set
|
|
*p = 0x00; p++; *len2 = *len2 + 1;
|
|
}
|
|
while (i < 64) { // copy bytes to output
|
|
*p = sig[i]; p++; *len2 = *len2 + 1; i++;
|
|
}
|
|
|
|
*len = *len1 + *len2 + 4;
|
|
return *len + 2;
|
|
}
|