b0edda11cb
Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/5689)
324 lines
7.2 KiB
C
324 lines
7.2 KiB
C
/*
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* Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
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* Copyright 2017 Ribose Inc. All Rights Reserved.
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* Ported from Ribose contributions from Botan.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <openssl/sm2.h>
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#include <openssl/evp.h>
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#include <openssl/bn.h>
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#include <string.h>
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static BIGNUM *compute_msg_hash(const EVP_MD *digest,
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const EC_KEY *key,
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const char *user_id,
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const uint8_t *msg, size_t msg_len)
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{
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EVP_MD_CTX *hash = EVP_MD_CTX_new();
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const int md_size = EVP_MD_size(digest);
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uint8_t *za = OPENSSL_zalloc(md_size);
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BIGNUM *e = NULL;
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if (za == NULL)
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goto done;
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if (hash == NULL)
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goto done;
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if (SM2_compute_userid_digest(za, digest, user_id, key) == 0)
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goto done;
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if (EVP_DigestInit(hash, digest) == 0)
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goto done;
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if (EVP_DigestUpdate(hash, za, md_size) == 0)
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goto done;
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if (EVP_DigestUpdate(hash, msg, msg_len) == 0)
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goto done;
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/* reuse za buffer to hold H(ZA || M) */
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if (EVP_DigestFinal(hash, za, NULL) == 0)
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goto done;
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e = BN_bin2bn(za, md_size, NULL);
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done:
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OPENSSL_free(za);
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EVP_MD_CTX_free(hash);
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return e;
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}
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static
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ECDSA_SIG *SM2_sig_gen(const EC_KEY *key, const BIGNUM *e)
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{
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const BIGNUM *dA = EC_KEY_get0_private_key(key);
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const EC_GROUP *group = EC_KEY_get0_group(key);
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const BIGNUM *order = EC_GROUP_get0_order(group);
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ECDSA_SIG *sig = NULL;
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EC_POINT *kG = NULL;
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BN_CTX *ctx = NULL;
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BIGNUM *k = NULL;
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BIGNUM *rk = NULL;
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BIGNUM *r = NULL;
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BIGNUM *s = NULL;
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BIGNUM *x1 = NULL;
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BIGNUM *tmp = NULL;
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kG = EC_POINT_new(group);
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if (kG == NULL)
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goto done;
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto done;
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BN_CTX_start(ctx);
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k = BN_CTX_get(ctx);
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rk = BN_CTX_get(ctx);
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x1 = BN_CTX_get(ctx);
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tmp = BN_CTX_get(ctx);
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if (tmp == NULL)
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goto done;
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/* These values are returned and so should not be allocated out of the context */
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r = BN_new();
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s = BN_new();
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if (r == NULL || s == NULL)
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goto done;
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for (;;) {
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BN_priv_rand_range(k, order);
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if (EC_POINT_mul(group, kG, k, NULL, NULL, ctx) == 0)
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goto done;
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if (EC_POINT_get_affine_coordinates_GFp(group, kG, x1, NULL, ctx) == 0)
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goto done;
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if (BN_mod_add(r, e, x1, order, ctx) == 0)
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goto done;
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/* try again if r == 0 or r+k == n */
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if (BN_is_zero(r))
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continue;
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BN_add(rk, r, k);
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if (BN_cmp(rk, order) == 0)
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continue;
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BN_add(s, dA, BN_value_one());
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BN_mod_inverse(s, s, order, ctx);
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BN_mod_mul(tmp, dA, r, order, ctx);
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BN_sub(tmp, k, tmp);
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BN_mod_mul(s, s, tmp, order, ctx);
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sig = ECDSA_SIG_new();
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if (sig == NULL)
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goto done;
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/* takes ownership of r and s */
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ECDSA_SIG_set0(sig, r, s);
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break;
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}
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done:
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if (sig == NULL) {
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BN_free(r);
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BN_free(s);
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}
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BN_CTX_free(ctx);
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EC_POINT_free(kG);
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return sig;
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}
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static
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int SM2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig, const BIGNUM *e)
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{
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int ret = 0;
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const EC_GROUP *group = EC_KEY_get0_group(key);
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const BIGNUM *order = EC_GROUP_get0_order(group);
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BN_CTX *ctx = NULL;
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EC_POINT *pt = NULL;
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BIGNUM *t = NULL;
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BIGNUM *x1 = NULL;
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const BIGNUM *r = NULL;
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const BIGNUM *s = NULL;
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto done;
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pt = EC_POINT_new(group);
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if (pt == NULL)
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goto done;
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BN_CTX_start(ctx);
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t = BN_CTX_get(ctx);
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x1 = BN_CTX_get(ctx);
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if (x1 == NULL)
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goto done;
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/*
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B1: verify whether r' in [1,n-1], verification failed if not
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B2: vefify whether s' in [1,n-1], verification failed if not
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B3: set M'~=ZA || M'
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B4: calculate e'=Hv(M'~)
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B5: calculate t = (r' + s') modn, verification failed if t=0
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B6: calculate the point (x1', y1')=[s']G + [t]PA
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B7: calculate R=(e'+x1') modn, verfication pass if yes, otherwise failed
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*/
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ECDSA_SIG_get0(sig, &r, &s);
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if (BN_cmp(r, BN_value_one()) < 0)
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goto done;
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if (BN_cmp(s, BN_value_one()) < 0)
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goto done;
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if (BN_cmp(order, r) <= 0)
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goto done;
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if (BN_cmp(order, s) <= 0)
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goto done;
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if (BN_mod_add(t, r, s, order, ctx) == 0)
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goto done;
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if (BN_is_zero(t) == 1)
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goto done;
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if (EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx) == 0)
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goto done;
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if (EC_POINT_get_affine_coordinates_GFp(group, pt, x1, NULL, ctx) == 0)
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goto done;
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if (BN_mod_add(t, e, x1, order, ctx) == 0)
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goto done;
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if (BN_cmp(r, t) == 0)
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ret = 1;
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done:
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EC_POINT_free(pt);
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BN_CTX_free(ctx);
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return ret;
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}
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ECDSA_SIG *SM2_do_sign(const EC_KEY *key,
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const EVP_MD *digest,
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const char *user_id, const uint8_t *msg, size_t msg_len)
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{
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BIGNUM *e = NULL;
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ECDSA_SIG *sig = NULL;
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e = compute_msg_hash(digest, key, user_id, msg, msg_len);
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if (e == NULL)
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goto done;
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sig = SM2_sig_gen(key, e);
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done:
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BN_free(e);
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return sig;
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}
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int SM2_do_verify(const EC_KEY *key,
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const EVP_MD *digest,
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const ECDSA_SIG *sig,
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const char *user_id, const uint8_t *msg, size_t msg_len)
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{
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BIGNUM *e = NULL;
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int ret = -1;
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e = compute_msg_hash(digest, key, user_id, msg, msg_len);
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if (e == NULL)
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goto done;
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ret = SM2_sig_verify(key, sig, e);
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done:
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BN_free(e);
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return ret;
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}
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int SM2_sign(int type, const unsigned char *dgst, int dgstlen,
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unsigned char *sig, unsigned int *siglen, EC_KEY *eckey)
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{
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BIGNUM *e = NULL;
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ECDSA_SIG *s = NULL;
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int ret = -1;
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if (type != NID_sm3)
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goto done;
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if (dgstlen != 32) /* expected length of SM3 hash */
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goto done;
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e = BN_bin2bn(dgst, dgstlen, NULL);
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s = SM2_sig_gen(eckey, e);
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*siglen = i2d_ECDSA_SIG(s, &sig);
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ECDSA_SIG_free(s);
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ret = 0;
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done:
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ECDSA_SIG_free(s);
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BN_free(e);
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return ret;
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}
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int SM2_verify(int type, const unsigned char *dgst, int dgstlen,
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const unsigned char *sig, int sig_len, EC_KEY *eckey)
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{
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ECDSA_SIG *s = NULL;
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BIGNUM *e = NULL;
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const unsigned char *p = sig;
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unsigned char *der = NULL;
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int derlen = -1;
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int ret = -1;
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if (type != NID_sm3)
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goto done;
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s = ECDSA_SIG_new();
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if (s == NULL)
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goto done;
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if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
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goto done;
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/* Ensure signature uses DER and doesn't have trailing garbage */
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derlen = i2d_ECDSA_SIG(s, &der);
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if (derlen != sig_len || memcmp(sig, der, derlen) != 0)
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goto done;
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e = BN_bin2bn(dgst, dgstlen, NULL);
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ret = SM2_sig_verify(eckey, s, e);
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done:
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OPENSSL_free(der);
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BN_free(e);
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ECDSA_SIG_free(s);
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return ret;
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}
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