ref: 4010db3078491baf3cb0d3d4e3a60c0cea114471
dir: /third_party/boringssl/src/crypto/fipsmodule/ecdsa/ecdsa.c/
/* ====================================================================
* 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/err.h>
#include <openssl/mem.h>
#include <openssl/sha.h>
#include <openssl/type_check.h>
#include "../../internal.h"
#include "../bn/internal.h"
#include "../ec/internal.h"
#include "internal.h"
// digest_to_scalar interprets |digest_len| bytes from |digest| as a scalar for
// ECDSA.
static void digest_to_scalar(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t *digest, size_t digest_len) {
const BIGNUM *order = &group->order;
size_t num_bits = BN_num_bits(order);
// Need to truncate digest if it is too long: first truncate whole bytes.
size_t num_bytes = (num_bits + 7) / 8;
if (digest_len > num_bytes) {
digest_len = num_bytes;
}
OPENSSL_memset(out, 0, sizeof(EC_SCALAR));
for (size_t i = 0; i < digest_len; i++) {
out->bytes[i] = digest[digest_len - 1 - i];
}
// If it is still too long, truncate remaining bits with a shift.
if (8 * digest_len > num_bits) {
bn_rshift_words(out->words, out->words, 8 - (num_bits & 0x7), order->width);
}
// |out| now has the same bit width as |order|, but this only bounds by
// 2*|order|. Subtract the order if out of range.
//
// Montgomery multiplication accepts the looser bounds, so this isn't strictly
// necessary, but it is a cleaner abstraction and has no performance impact.
BN_ULONG tmp[EC_MAX_WORDS];
bn_reduce_once_in_place(out->words, 0 /* no carry */, order->d, tmp,
order->width);
}
ECDSA_SIG *ECDSA_SIG_new(void) {
ECDSA_SIG *sig = OPENSSL_malloc(sizeof(ECDSA_SIG));
if (sig == NULL) {
return NULL;
}
sig->r = BN_new();
sig->s = BN_new();
if (sig->r == NULL || sig->s == NULL) {
ECDSA_SIG_free(sig);
return NULL;
}
return sig;
}
void ECDSA_SIG_free(ECDSA_SIG *sig) {
if (sig == NULL) {
return;
}
BN_free(sig->r);
BN_free(sig->s);
OPENSSL_free(sig);
}
const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig) {
return sig->r;
}
const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig) {
return sig->s;
}
void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **out_r,
const BIGNUM **out_s) {
if (out_r != NULL) {
*out_r = sig->r;
}
if (out_s != NULL) {
*out_s = sig->s;
}
}
int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s) {
if (r == NULL || s == NULL) {
return 0;
}
BN_free(sig->r);
BN_free(sig->s);
sig->r = r;
sig->s = s;
return 1;
}
int ECDSA_do_verify(const uint8_t *digest, size_t digest_len,
const ECDSA_SIG *sig, const EC_KEY *eckey) {
const EC_GROUP *group = EC_KEY_get0_group(eckey);
const EC_POINT *pub_key = EC_KEY_get0_public_key(eckey);
if (group == NULL || pub_key == NULL || sig == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_MISSING_PARAMETERS);
return 0;
}
EC_SCALAR r, s, u1, u2, s_inv_mont, m;
if (BN_is_zero(sig->r) ||
!ec_bignum_to_scalar(group, &r, sig->r) ||
BN_is_zero(sig->s) ||
!ec_bignum_to_scalar(group, &s, sig->s)) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_BAD_SIGNATURE);
return 0;
}
// s_inv_mont = s^-1 in the Montgomery domain.
if (!ec_scalar_to_montgomery_inv_vartime(group, &s_inv_mont, &s)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_INTERNAL_ERROR);
return 0;
}
// u1 = m * s^-1 mod order
// u2 = r * s^-1 mod order
//
// |s_inv_mont| is in Montgomery form while |m| and |r| are not, so |u1| and
// |u2| will be taken out of Montgomery form, as desired.
digest_to_scalar(group, &m, digest, digest_len);
ec_scalar_mul_montgomery(group, &u1, &m, &s_inv_mont);
ec_scalar_mul_montgomery(group, &u2, &r, &s_inv_mont);
EC_RAW_POINT point;
if (!ec_point_mul_scalar_public(group, &point, &u1, &pub_key->raw, &u2)) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_EC_LIB);
return 0;
}
if (!ec_cmp_x_coordinate(group, &point, &r)) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_BAD_SIGNATURE);
return 0;
}
return 1;
}
static ECDSA_SIG *ecdsa_sign_impl(const EC_GROUP *group, int *out_retry,
const EC_SCALAR *priv_key, const EC_SCALAR *k,
const uint8_t *digest, size_t digest_len) {
*out_retry = 0;
// Check that the size of the group order is FIPS compliant (FIPS 186-4
// B.5.2).
const BIGNUM *order = EC_GROUP_get0_order(group);
if (BN_num_bits(order) < 160) {
OPENSSL_PUT_ERROR(ECDSA, EC_R_INVALID_GROUP_ORDER);
return NULL;
}
// Compute r, the x-coordinate of k * generator.
EC_RAW_POINT tmp_point;
EC_SCALAR r;
if (!ec_point_mul_scalar_base(group, &tmp_point, k) ||
!ec_get_x_coordinate_as_scalar(group, &r, &tmp_point)) {
return NULL;
}
if (ec_scalar_is_zero(group, &r)) {
*out_retry = 1;
return NULL;
}
// s = priv_key * r. Note if only one parameter is in the Montgomery domain,
// |ec_scalar_mod_mul_montgomery| will compute the answer in the normal
// domain.
EC_SCALAR s;
ec_scalar_to_montgomery(group, &s, &r);
ec_scalar_mul_montgomery(group, &s, priv_key, &s);
// s = m + priv_key * r.
EC_SCALAR tmp;
digest_to_scalar(group, &tmp, digest, digest_len);
ec_scalar_add(group, &s, &s, &tmp);
// s = k^-1 * (m + priv_key * r). First, we compute k^-1 in the Montgomery
// domain. This is |ec_scalar_to_montgomery| followed by
// |ec_scalar_inv0_montgomery|, but |ec_scalar_inv0_montgomery| followed by
// |ec_scalar_from_montgomery| is equivalent and slightly more efficient.
// Then, as above, only one parameter is in the Montgomery domain, so the
// result is in the normal domain. Finally, note k is non-zero (or computing r
// would fail), so the inverse must exist.
ec_scalar_inv0_montgomery(group, &tmp, k); // tmp = k^-1 R^2
ec_scalar_from_montgomery(group, &tmp, &tmp); // tmp = k^-1 R
ec_scalar_mul_montgomery(group, &s, &s, &tmp);
if (ec_scalar_is_zero(group, &s)) {
*out_retry = 1;
return NULL;
}
ECDSA_SIG *ret = ECDSA_SIG_new();
if (ret == NULL || //
!bn_set_words(ret->r, r.words, order->width) ||
!bn_set_words(ret->s, s.words, order->width)) {
ECDSA_SIG_free(ret);
return NULL;
}
return ret;
}
ECDSA_SIG *ecdsa_sign_with_nonce_for_known_answer_test(const uint8_t *digest,
size_t digest_len,
const EC_KEY *eckey,
const uint8_t *nonce,
size_t nonce_len) {
if (eckey->ecdsa_meth && eckey->ecdsa_meth->sign) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_NOT_IMPLEMENTED);
return NULL;
}
const EC_GROUP *group = EC_KEY_get0_group(eckey);
if (group == NULL || eckey->priv_key == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
const EC_SCALAR *priv_key = &eckey->priv_key->scalar;
EC_SCALAR k;
if (!ec_scalar_from_bytes(group, &k, nonce, nonce_len)) {
return NULL;
}
int retry_ignored;
return ecdsa_sign_impl(group, &retry_ignored, priv_key, &k, digest,
digest_len);
}
// This function is only exported for testing and is not called in production
// code.
ECDSA_SIG *ECDSA_sign_with_nonce_and_leak_private_key_for_testing(
const uint8_t *digest, size_t digest_len, const EC_KEY *eckey,
const uint8_t *nonce, size_t nonce_len) {
return ecdsa_sign_with_nonce_for_known_answer_test(digest, digest_len, eckey,
nonce, nonce_len);
}
ECDSA_SIG *ECDSA_do_sign(const uint8_t *digest, size_t digest_len,
const EC_KEY *eckey) {
if (eckey->ecdsa_meth && eckey->ecdsa_meth->sign) {
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_NOT_IMPLEMENTED);
return NULL;
}
const EC_GROUP *group = EC_KEY_get0_group(eckey);
if (group == NULL || eckey->priv_key == NULL) {
OPENSSL_PUT_ERROR(ECDSA, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
const BIGNUM *order = EC_GROUP_get0_order(group);
const EC_SCALAR *priv_key = &eckey->priv_key->scalar;
// Pass a SHA512 hash of the private key and digest as additional data
// into the RBG. This is a hardening measure against entropy failure.
OPENSSL_STATIC_ASSERT(SHA512_DIGEST_LENGTH >= 32,
"additional_data is too large for SHA-512");
SHA512_CTX sha;
uint8_t additional_data[SHA512_DIGEST_LENGTH];
SHA512_Init(&sha);
SHA512_Update(&sha, priv_key->words, order->width * sizeof(BN_ULONG));
SHA512_Update(&sha, digest, digest_len);
SHA512_Final(additional_data, &sha);
for (;;) {
EC_SCALAR k;
if (!ec_random_nonzero_scalar(group, &k, additional_data)) {
return NULL;
}
int retry;
ECDSA_SIG *sig =
ecdsa_sign_impl(group, &retry, priv_key, &k, digest, digest_len);
if (sig != NULL || !retry) {
return sig;
}
}
}