456 lines
14 KiB
C
456 lines
14 KiB
C
/*
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* Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
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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 <string.h>
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#include <openssl/err.h>
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#include <openssl/obj_mac.h>
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#include <openssl/bn.h>
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#include <openssl/rand.h>
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#include <openssl/ec.h>
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#include "ec_lcl.h"
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int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
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unsigned char *sig, unsigned int *siglen,
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const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
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{
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ECDSA_SIG *s;
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RAND_seed(dgst, dlen);
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s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
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if (s == NULL) {
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*siglen = 0;
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return 0;
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}
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*siglen = i2d_ECDSA_SIG(s, &sig);
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ECDSA_SIG_free(s);
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return 1;
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}
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static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
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BIGNUM **kinvp, BIGNUM **rp,
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const unsigned char *dgst, int dlen)
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{
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BN_CTX *ctx = NULL;
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BIGNUM *k = NULL, *r = NULL, *X = NULL;
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const BIGNUM *order;
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EC_POINT *tmp_point = NULL;
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const EC_GROUP *group;
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int ret = 0;
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if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
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return 0;
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}
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if (!EC_KEY_can_sign(eckey)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
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return 0;
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}
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if (ctx_in == NULL) {
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if ((ctx = BN_CTX_new()) == NULL) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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} else
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ctx = ctx_in;
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k = BN_new(); /* this value is later returned in *kinvp */
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r = BN_new(); /* this value is later returned in *rp */
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X = BN_new();
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if (k == NULL || r == NULL || X == NULL) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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if ((tmp_point = EC_POINT_new(group)) == NULL) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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order = EC_GROUP_get0_order(group);
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if (order == NULL) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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do {
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/* get random k */
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do
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if (dgst != NULL) {
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if (!BN_generate_dsa_nonce
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(k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
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ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP,
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EC_R_RANDOM_NUMBER_GENERATION_FAILED);
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goto err;
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}
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} else {
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if (!BN_rand_range(k, order)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP,
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EC_R_RANDOM_NUMBER_GENERATION_FAILED);
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goto err;
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}
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}
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while (BN_is_zero(k));
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/*
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* We do not want timing information to leak the length of k, so we
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* compute G*k using an equivalent scalar of fixed bit-length.
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*/
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if (!BN_add(k, k, order))
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goto err;
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if (BN_num_bits(k) <= BN_num_bits(order))
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if (!BN_add(k, k, order))
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goto err;
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/* compute r the x-coordinate of generator * k */
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if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
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NID_X9_62_prime_field) {
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if (!EC_POINT_get_affine_coordinates_GFp
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(group, tmp_point, X, NULL, ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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}
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#ifndef OPENSSL_NO_EC2M
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else { /* NID_X9_62_characteristic_two_field */
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if (!EC_POINT_get_affine_coordinates_GF2m(group,
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tmp_point, X, NULL,
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ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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}
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#endif
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if (!BN_nnmod(r, X, order, ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
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goto err;
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}
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}
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while (BN_is_zero(r));
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/* compute the inverse of k */
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if (EC_GROUP_get_mont_data(group) != NULL) {
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/*
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* We want inverse in constant time, therefore we utilize the fact
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* order must be prime and use Fermats Little Theorem instead.
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*/
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if (!BN_set_word(X, 2)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
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goto err;
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}
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if (!BN_mod_sub(X, order, X, order, ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
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goto err;
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}
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BN_set_flags(X, BN_FLG_CONSTTIME);
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if (!BN_mod_exp_mont_consttime
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(k, k, X, order, ctx, EC_GROUP_get_mont_data(group))) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
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goto err;
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}
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} else {
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if (!BN_mod_inverse(k, k, order, ctx)) {
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ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
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goto err;
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}
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}
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/* clear old values if necessary */
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BN_clear_free(*rp);
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BN_clear_free(*kinvp);
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/* save the pre-computed values */
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*rp = r;
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*kinvp = k;
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ret = 1;
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err:
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if (!ret) {
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BN_clear_free(k);
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BN_clear_free(r);
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}
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if (ctx != ctx_in)
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BN_CTX_free(ctx);
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EC_POINT_free(tmp_point);
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BN_clear_free(X);
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return (ret);
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}
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int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
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BIGNUM **rp)
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{
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return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
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}
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ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
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const BIGNUM *in_kinv, const BIGNUM *in_r,
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EC_KEY *eckey)
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{
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int ok = 0, i;
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BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL;
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const BIGNUM *order, *ckinv;
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BN_CTX *ctx = NULL;
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const EC_GROUP *group;
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ECDSA_SIG *ret;
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const BIGNUM *priv_key;
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group = EC_KEY_get0_group(eckey);
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priv_key = EC_KEY_get0_private_key(eckey);
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if (group == NULL || priv_key == NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
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return NULL;
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}
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if (!EC_KEY_can_sign(eckey)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
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return NULL;
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}
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ret = ECDSA_SIG_new();
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if (ret == NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
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return NULL;
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}
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s = ret->s;
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if ((ctx = BN_CTX_new()) == NULL ||
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(tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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order = EC_GROUP_get0_order(group);
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if (order == NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_EC_LIB);
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goto err;
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}
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i = BN_num_bits(order);
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/*
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* Need to truncate digest if it is too long: first truncate whole bytes.
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*/
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if (8 * dgst_len > i)
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dgst_len = (i + 7) / 8;
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if (!BN_bin2bn(dgst, dgst_len, m)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* If still too long truncate remaining bits with a shift */
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if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
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goto err;
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}
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do {
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if (in_kinv == NULL || in_r == NULL) {
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if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
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goto err;
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}
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ckinv = kinv;
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} else {
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ckinv = in_kinv;
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if (BN_copy(ret->r, in_r) == NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
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goto err;
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}
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if (!BN_mod_add_quick(s, tmp, m, order)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
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goto err;
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}
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if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
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goto err;
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}
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if (BN_is_zero(s)) {
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/*
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* if kinv and r have been supplied by the caller don't to
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* generate new kinv and r values
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*/
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if (in_kinv != NULL && in_r != NULL) {
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ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
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goto err;
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}
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} else
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/* s != 0 => we have a valid signature */
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break;
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}
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while (1);
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ok = 1;
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err:
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if (!ok) {
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ECDSA_SIG_free(ret);
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ret = NULL;
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}
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BN_CTX_free(ctx);
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BN_clear_free(m);
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BN_clear_free(tmp);
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BN_clear_free(kinv);
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return ret;
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}
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/*-
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* returns
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* 1: correct signature
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* 0: incorrect signature
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* -1: error
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*/
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int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
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const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
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{
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ECDSA_SIG *s;
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const unsigned char *p = sigbuf;
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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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s = ECDSA_SIG_new();
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if (s == NULL)
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return (ret);
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if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
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goto err;
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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(sigbuf, der, derlen) != 0)
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goto err;
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ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
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err:
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OPENSSL_clear_free(der, derlen);
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ECDSA_SIG_free(s);
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return (ret);
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}
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int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
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const ECDSA_SIG *sig, EC_KEY *eckey)
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{
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int ret = -1, i;
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BN_CTX *ctx;
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const BIGNUM *order;
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BIGNUM *u1, *u2, *m, *X;
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EC_POINT *point = NULL;
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const EC_GROUP *group;
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const EC_POINT *pub_key;
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/* check input values */
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if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
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(pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
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return -1;
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}
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if (!EC_KEY_can_sign(eckey)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
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return -1;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
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return -1;
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}
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BN_CTX_start(ctx);
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u1 = BN_CTX_get(ctx);
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u2 = BN_CTX_get(ctx);
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m = BN_CTX_get(ctx);
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X = BN_CTX_get(ctx);
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if (X == NULL) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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order = EC_GROUP_get0_order(group);
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if (order == NULL) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
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goto err;
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}
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if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
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BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
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BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
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ret = 0; /* signature is invalid */
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goto err;
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}
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/* calculate tmp1 = inv(S) mod order */
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if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* digest -> m */
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i = BN_num_bits(order);
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/*
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* Need to truncate digest if it is too long: first truncate whole bytes.
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*/
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if (8 * dgst_len > i)
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dgst_len = (i + 7) / 8;
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if (!BN_bin2bn(dgst, dgst_len, m)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* If still too long truncate remaining bits with a shift */
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if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* u1 = m * tmp mod order */
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if (!BN_mod_mul(u1, m, u2, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* u2 = r * w mod q */
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if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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if ((point = EC_POINT_new(group)) == NULL) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
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goto err;
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}
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if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
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NID_X9_62_prime_field) {
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if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
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goto err;
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}
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}
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#ifndef OPENSSL_NO_EC2M
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else { /* NID_X9_62_characteristic_two_field */
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if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
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goto err;
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}
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}
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#endif
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if (!BN_nnmod(u1, X, order, ctx)) {
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ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
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goto err;
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}
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/* if the signature is correct u1 is equal to sig->r */
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ret = (BN_ucmp(u1, sig->r) == 0);
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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EC_POINT_free(point);
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return ret;
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}
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