493 lines
16 KiB
C
493 lines
16 KiB
C
/* crypto/ecdsa/ecs_ossl.c */
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/*
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* Written by Nils Larsch for the OpenSSL project
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*/
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/* ====================================================================
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* Copyright (c) 1998-2018 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@OpenSSL.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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#include "ecs_locl.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 "bn_int.h"
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static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
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const BIGNUM *, const BIGNUM *,
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EC_KEY *eckey);
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static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
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BIGNUM **rp);
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static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
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const ECDSA_SIG *sig, EC_KEY *eckey);
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static ECDSA_METHOD openssl_ecdsa_meth = {
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"OpenSSL ECDSA method",
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ecdsa_do_sign,
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ecdsa_sign_setup,
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ecdsa_do_verify,
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#if 0
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NULL, /* init */
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NULL, /* finish */
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#endif
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0, /* flags */
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NULL /* app_data */
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};
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const ECDSA_METHOD *ECDSA_OpenSSL(void)
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{
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return &openssl_ecdsa_meth;
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}
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static int 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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BN_CTX *ctx = NULL;
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BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
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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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int order_bits;
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if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
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ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
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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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ECDSAerr(ECDSA_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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order = BN_new();
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X = BN_new();
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if (!k || !r || !order || !X) {
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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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if (!EC_GROUP_get_order(group, order, ctx)) {
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ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
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goto err;
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}
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/* Preallocate space */
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order_bits = BN_num_bits(order);
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if (!BN_set_bit(k, order_bits)
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|| !BN_set_bit(r, order_bits)
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|| !BN_set_bit(X, order_bits))
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goto err;
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do {
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/* get random k */
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do
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if (!BN_rand_range(k, order)) {
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ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
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ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
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goto err;
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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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* We unconditionally perform both of these additions to prevent a
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* small timing information leakage. We then choose the sum that is
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* one bit longer than the order. This guarantees the code
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* path used in the constant time implementations elsewhere.
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*
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* TODO: revisit the BN_copy aiming for a memory access agnostic
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* conditional copy.
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*/
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if (!BN_add(r, k, order)
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|| !BN_add(X, r, order)
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|| !BN_copy(k, BN_num_bits(r) > order_bits ? r : X))
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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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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ECDSAerr(ECDSA_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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if (*rp != NULL)
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BN_clear_free(*rp);
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if (*kinvp != NULL)
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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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if (k != NULL)
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BN_clear_free(k);
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if (r != NULL)
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BN_clear_free(r);
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}
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if (ctx_in == NULL)
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BN_CTX_free(ctx);
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if (order != NULL)
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BN_free(order);
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if (tmp_point != NULL)
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EC_POINT_free(tmp_point);
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if (X)
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BN_clear_free(X);
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return (ret);
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}
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static ECDSA_SIG *ecdsa_do_sign(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, *order = NULL;
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const BIGNUM *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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ECDSA_DATA *ecdsa;
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const BIGNUM *priv_key;
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BN_MONT_CTX *mont_data;
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ecdsa = ecdsa_check(eckey);
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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 || ecdsa == NULL) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
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return NULL;
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}
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ret = ECDSA_SIG_new();
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if (!ret) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 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 || (order = BN_new()) == NULL ||
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(m = BN_new()) == NULL) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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if (!EC_GROUP_get_order(group, order, ctx)) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
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goto err;
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}
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mont_data = EC_GROUP_get_mont_data(group);
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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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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 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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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 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)) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 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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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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/*
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* With only one multiplicant being in Montgomery domain
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* multiplication yields real result without post-conversion.
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* Also note that all operations but last are performed with
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* zero-padded vectors. Last operation, BN_mod_mul_montgomery
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* below, returns user-visible value with removed zero padding.
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*/
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if (!bn_to_mont_fixed_top(s, ret->r, mont_data, ctx)
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|| !bn_mul_mont_fixed_top(s, s, priv_key, mont_data, ctx)) {
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goto err;
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}
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if (!bn_mod_add_fixed_top(s, s, m, order)) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
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goto err;
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}
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/*
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* |s| can still be larger than modulus, because |m| can be. In
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* such case we count on Montgomery reduction to tie it up.
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*/
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if (!bn_to_mont_fixed_top(s, s, mont_data, ctx)
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|| !BN_mod_mul_montgomery(s, s, ckinv, mont_data, ctx)) {
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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 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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ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
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ECDSA_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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if (ctx)
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BN_CTX_free(ctx);
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if (m)
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BN_clear_free(m);
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if (order)
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BN_free(order);
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if (kinv)
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BN_clear_free(kinv);
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return ret;
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}
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static int ecdsa_do_verify(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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BIGNUM *order, *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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
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return -1;
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}
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ctx = BN_CTX_new();
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if (!ctx) {
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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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order = BN_CTX_get(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) {
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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
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goto err;
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}
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if (!EC_GROUP_get_order(group, order, ctx)) {
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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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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ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, 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)) {
|
|
ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
|
|
goto err;
|
|
}
|
|
}
|
|
#ifndef OPENSSL_NO_EC2M
|
|
else { /* NID_X9_62_characteristic_two_field */
|
|
|
|
if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
|
|
ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
|
|
goto err;
|
|
}
|
|
}
|
|
#endif
|
|
if (!BN_nnmod(u1, X, order, ctx)) {
|
|
ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
|
|
goto err;
|
|
}
|
|
/* if the signature is correct u1 is equal to sig->r */
|
|
ret = (BN_ucmp(u1, sig->r) == 0);
|
|
err:
|
|
BN_CTX_end(ctx);
|
|
BN_CTX_free(ctx);
|
|
if (point)
|
|
EC_POINT_free(point);
|
|
return ret;
|
|
}
|