/* ====================================================================
* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/ecdsa.h>
#include <assert.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "../bn/internal.h"
#include "../ec/internal.h"
#include "../internal.h"
int ECDSA_sign(int type, const uint8_t *digest, size_t digest_len, uint8_t *sig,
unsigned int *sig_len, const EC_KEY *eckey) {
if (eckey->ecdsa_meth && eckey->ecdsa_meth->sign) {
return eckey->ecdsa_meth->sign(digest, digest_len, sig, sig_len,
(EC_KEY*) eckey /* cast away const */);
}
return ECDSA_sign_ex(type, digest, digest_len, sig, sig_len, NULL, NULL,
eckey);
}
int ECDSA_verify(int type, const uint8_t *digest, size_t digest_len,
const uint8_t *sig, size_t sig_len, const EC_KEY *eckey) {
ECDSA_SIG *s;
int ret = 0;
uint8_t *der = NULL;
/* Decode the ECDSA signature. */
s = ECDSA_SIG_from_bytes(sig, sig_len);
if (s == NULL) {
goto err;
}
/* Defend against potential laxness in the DER parser. */
size_t der_len;
if (!ECDSA_SIG_to_bytes(&der, &der_len, s) ||
der_len != sig_len || OPENSSL_memcmp(sig, der, sig_len) != 0) {
/* This should never happen. crypto/bytestring is strictly DER. */
OPENSSL_PUT_ERROR(ECDSA, ERR_R_INTERNAL_ERROR);
goto err;
}
ret = ECDSA_do_verify(digest, digest_len, s, eckey);
err:
OPENSSL_free(der);
ECDSA_SIG_free(s);
return ret;
}
/* digest_to_bn interprets |digest_len| bytes from |digest| as a big-endian
* number and sets |out| to that value. It then truncates |out| so that it's,
* at most, as long as |order|. It returns one on success and zero otherwise. */
static int digest_to_bn(BIGNUM *out, const uint8_t *digest, size_t digest_len,
const BIGNUM *order) {
size_t num_bits;
num_bits = BN_num_bits(order);
/* Need to truncate digest if it is too long: first truncate whole
* bytes. */
if (8 * digest_len > num_bits) {
digest_len = (num_bits + 7) / 8;
}
if (!BN_bin2bn(digest, digest_len, out)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
return 0;
}
/* If still too long truncate remaining bits with a shift */
if ((8 * digest_len > num_bits) &&
!BN_rshift(out, out, 8 - (num_bits & 0x7))) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
return 0;
}
return 1;
}
ECDSA_SIG *ECDSA_do_sign(const uint8_t *digest, size_t digest_len,
const EC_KEY *key) {
return ECDSA_do_sign_ex(digest, digest_len, NULL, NULL, key);
}
int ECDSA_do_verify(const uint8_t *digest, size_t digest_len,
const ECDSA_SIG *sig, const EC_KEY *eckey) {
int ret = 0;
BN_CTX *ctx;
BIGNUM *u1, *u2, *m, *X;
EC_POINT *point = NULL;
const EC_GROUP *group;
const EC_POINT *pub_key;
/* check input values */
if ((group = EC_KEY_get0_group(eckey)) == NULL ||
(pub_key = EC_KEY_get0_public_key(eckey)) == NULL ||
sig == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_MISSING_PARAMETERS);
return 0;
}
ctx = BN_CTX_new();
if (!ctx) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
return 0;
}
BN_CTX_start(ctx);
u1 = BN_CTX_get(ctx);
u2 = BN_CTX_get(ctx);
m = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
if (u1 == NULL || u2 == NULL || m == NULL || X == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
const BIGNUM *order = EC_GROUP_get0_order(group);
if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_BAD_SIGNATURE);
ret = 0; /* signature is invalid */
goto err;
}
/* calculate tmp1 = inv(S) mod order */
int no_inverse;
if (!BN_mod_inverse_odd(u2, &no_inverse, sig->s, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
if (!digest_to_bn(m, digest, digest_len, order)) {
goto err;
}
/* u1 = m * tmp mod order */
if (!BN_mod_mul(u1, m, u2, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
/* u2 = r * w mod q */
if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
point = EC_POINT_new(group);
if (point == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
goto err;
}
if (!BN_nnmod(u1, X, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, 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);
EC_POINT_free(point);
return ret;
}
static int ecdsa_sign_setup(const EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
BIGNUM **rp, const uint8_t *digest,
size_t digest_len) {
BN_CTX *ctx = NULL;
BIGNUM *k = NULL, *r = NULL, *tmp = NULL;
EC_POINT *tmp_point = NULL;
const EC_GROUP *group;
int ret = 0;
if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if (ctx_in == NULL) {
if ((ctx = BN_CTX_new()) == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
return 0;
}
} else {
ctx = ctx_in;
}
k = BN_new(); /* this value is later returned in *kinvp */
r = BN_new(); /* this value is later returned in *rp */
tmp = BN_new();
if (k == NULL || r == NULL || tmp == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
goto err;
}
tmp_point = EC_POINT_new(group);
if (tmp_point == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
goto err;
}
const BIGNUM *order = EC_GROUP_get0_order(group);
do {
/* If possible, we'll include the private key and message digest in the k
* generation. The |digest| argument is only empty if |ECDSA_sign_setup| is
* being used. */
if (digest_len > 0) {
do {
if (!BN_generate_dsa_nonce(k, order, EC_KEY_get0_private_key(eckey),
digest, digest_len, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
goto err;
}
} while (BN_is_zero(k));
} else if (!BN_rand_range_ex(k, 1, order)) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
goto err;
}
/* We do not want timing information to leak the length of k,
* so we compute G*k using an equivalent scalar of fixed
* bit-length. */
if (!BN_add(k, k, order)) {
goto err;
}
if (BN_num_bits(k) <= BN_num_bits(order)) {
if (!BN_add(k, k, order)) {
goto err;
}
}
/* compute r the x-coordinate of generator * k */
if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp_point, tmp, NULL,
ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
goto err;
}
if (!BN_nnmod(r, tmp, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
} while (BN_is_zero(r));
/* Compute the inverse of k. The order is a prime, so use Fermat's Little
* Theorem. Note |ec_group_get_mont_data| may return NULL but
* |bn_mod_inverse_prime| allows this. */
if (!bn_mod_inverse_prime(k, k, order, ctx, ec_group_get_mont_data(group))) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
/* clear old values if necessary */
BN_clear_free(*rp);
BN_clear_free(*kinvp);
/* save the pre-computed values */
*rp = r;
*kinvp = k;
ret = 1;
err:
if (!ret) {
BN_clear_free(k);
BN_clear_free(r);
}
if (ctx_in == NULL) {
BN_CTX_free(ctx);
}
EC_POINT_free(tmp_point);
BN_clear_free(tmp);
return ret;
}
int ECDSA_sign_setup(const EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv,
BIGNUM **rp) {
return ecdsa_sign_setup(eckey, ctx, kinv, rp, NULL, 0);
}
ECDSA_SIG *ECDSA_do_sign_ex(const uint8_t *digest, size_t digest_len,
const BIGNUM *in_kinv, const BIGNUM *in_r,
const EC_KEY *eckey) {
int ok = 0;
BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL;
const BIGNUM *ckinv;
BN_CTX *ctx = NULL;
const EC_GROUP *group;
ECDSA_SIG *ret;
const BIGNUM *priv_key;
if (eckey->ecdsa_meth && eckey->ecdsa_meth->sign) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_NOT_IMPLEMENTED);
return NULL;
}
group = EC_KEY_get0_group(eckey);
priv_key = EC_KEY_get0_private_key(eckey);
if (group == NULL || priv_key == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
ret = ECDSA_SIG_new();
if (!ret) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
return NULL;
}
s = ret->s;
if ((ctx = BN_CTX_new()) == NULL ||
(tmp = BN_new()) == NULL ||
(m = BN_new()) == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
goto err;
}
const BIGNUM *order = EC_GROUP_get0_order(group);
if (!digest_to_bn(m, digest, digest_len, order)) {
goto err;
}
for (;;) {
if (in_kinv == NULL || in_r == NULL) {
if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, digest, digest_len)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_ECDSA_LIB);
goto err;
}
ckinv = kinv;
} else {
ckinv = in_kinv;
if (BN_copy(ret->r, in_r) == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_MALLOC_FAILURE);
goto err;
}
}
if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
if (!BN_mod_add_quick(s, tmp, m, order)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
goto err;
}
if (BN_is_zero(s)) {
/* if kinv and r have been supplied by the caller
* don't to generate new kinv and r values */
if (in_kinv != NULL && in_r != NULL) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_NEED_NEW_SETUP_VALUES);
goto err;
}
} else {
/* s != 0 => we have a valid signature */
break;
}
}
ok = 1;
err:
if (!ok) {
ECDSA_SIG_free(ret);
ret = NULL;
}
BN_CTX_free(ctx);
BN_clear_free(m);
BN_clear_free(tmp);
BN_clear_free(kinv);
return ret;
}
int ECDSA_sign_ex(int type, const uint8_t *digest, size_t digest_len,
uint8_t *sig, unsigned int *sig_len, const BIGNUM *kinv,
const BIGNUM *r, const EC_KEY *eckey) {
int ret = 0;
ECDSA_SIG *s = NULL;
if (eckey->ecdsa_meth && eckey->ecdsa_meth->sign) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_NOT_IMPLEMENTED);
*sig_len = 0;
goto err;
}
s = ECDSA_do_sign_ex(digest, digest_len, kinv, r, eckey);
if (s == NULL) {
*sig_len = 0;
goto err;
}
CBB cbb;
CBB_zero(&cbb);
size_t len;
if (!CBB_init_fixed(&cbb, sig, ECDSA_size(eckey)) ||
!ECDSA_SIG_marshal(&cbb, s) ||
!CBB_finish(&cbb, NULL, &len)) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_ENCODE_ERROR);
CBB_cleanup(&cbb);
*sig_len = 0;
goto err;
}
*sig_len = (unsigned)len;
ret = 1;
err:
ECDSA_SIG_free(s);
return ret;
}