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Create sm2_sign_fast.c

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Zhi Guan
2022-10-23 10:51:58 +08:00
parent 17c54645cb
commit 186dd06695
1 changed files with 61 additions and 0 deletions
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/*
* Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
*
* http://www.apache.org/licenses/LICENSE-2.0
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <stdint.h>
#include <gmssl/sm2.h>
#include <gmssl/error.h>
// (x1, y1) = k * G
// r = e + x1
// s = (k - r * d)/(1 + d) = (k +r - r * d - r)/(1 + d) = (k + r - r(1 +d))/(1 + d) = (k + r)/(1 + d) - r
// = -r + (k + r)*(1 + d)^-1
// = -r + (k + r) * d'
int sm2_do_sign_fast(const SM2_Fn d, const uint8_t dgst[32], SM2_SIGNATURE *sig)
{
SM2_JACOBIAN_POINT R;
SM2_BN e;
SM2_BN k;
SM2_BN x1;
SM2_BN r;
SM2_BN s;
// e = H(M)
sm2_bn_from_bytes(e, dgst);
if (sm2_bn_cmp(e, SM2_N) >= 0) {
sm2_bn_sub(e, e, SM2_N);
}
// rand k in [1, n - 1]
do {
sm2_fn_rand(k);
} while (sm2_bn_is_zero(k));
// (x1, y1) = kG
sm2_jacobian_point_mul_generator(&R, k);
sm2_jacobian_point_get_xy(&R, x1, NULL);
// r = e + x1 (mod n)
sm2_fn_add(r, e, x1);
// s = (k + r) * d' - r
sm2_bn_add(s, k, r);
sm2_fn_mul(s, s, d);
sm2_fn_sub(s, s, r);
sm2_bn_to_bytes(r, sig->r);
sm2_bn_to_bytes(s, sig->s);
return 1;
}