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Re-arrange SM2

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This commit is contained in:
Zhi Guan
2022-11-02 22:01:23 +08:00
parent d72866b28e
commit 9dfc5e5d80
7 changed files with 94 additions and 130 deletions
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44
src/sm2_lib.c
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@@ -706,3 +706,47 @@ int sm2_ecdh(const SM2_KEY *key, const SM2_POINT *peer_public, SM2_POINT *out)
}
return 1;
}
// (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;
}