417 lines
13 KiB
C
417 lines
13 KiB
C
// Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
|
|
// SPDX-License-Identifier: Apache-2.0
|
|
|
|
#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 <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 = EC_GROUP_get0_order(group);
|
|
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;
|
|
}
|
|
bn_big_endian_to_words(out->words, order->width, digest, digest_len);
|
|
|
|
// 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_no_self_test(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_JACOBIAN 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_MISMATCHED_SIGNATURE);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
int ECDSA_do_verify(const uint8_t *digest, size_t digest_len,
|
|
const ECDSA_SIG *sig, const EC_KEY *eckey) {
|
|
boringssl_ensure_ecc_self_test();
|
|
|
|
return ecdsa_do_verify_no_self_test(digest, digest_len, sig, eckey);
|
|
}
|
|
|
|
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_JACOBIAN 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 (constant_time_declassify_int(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 (constant_time_declassify_int(ec_scalar_is_zero(group, &s))) {
|
|
*out_retry = 1;
|
|
return NULL;
|
|
}
|
|
|
|
CONSTTIME_DECLASSIFY(r.words, sizeof(r.words));
|
|
CONSTTIME_DECLASSIFY(s.words, sizeof(r.words));
|
|
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->eckey_method && eckey->eckey_method->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) {
|
|
boringssl_ensure_ecc_self_test();
|
|
|
|
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) {
|
|
boringssl_ensure_ecc_self_test();
|
|
|
|
if (eckey->eckey_method && eckey->eckey_method->sign_sig) {
|
|
return eckey->eckey_method->sign_sig(digest, (int)digest_len, NULL, NULL,
|
|
(EC_KEY *)eckey);
|
|
}
|
|
|
|
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;
|
|
}
|
|
// We have to avoid the underlying |SHA512_Final| services updating the
|
|
// indicator state, so we lock the state here.
|
|
FIPS_service_indicator_lock_state();
|
|
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);
|
|
|
|
FIPS_service_indicator_unlock_state();
|
|
// Cap iterations so callers who supply invalid values as custom groups do not
|
|
// infinite loop. This does not impact valid parameters (e.g. those covered by
|
|
// FIPS) because the probability of requiring even one retry is negligible,
|
|
// let alone 32.
|
|
static const int kMaxIterations = 32;
|
|
int iters = 0;
|
|
for (;;) {
|
|
EC_SCALAR k;
|
|
if (!ec_random_nonzero_scalar(group, &k, additional_data)) {
|
|
OPENSSL_cleanse(&k, sizeof(EC_SCALAR));
|
|
return NULL;
|
|
}
|
|
|
|
// TODO(davidben): Move this inside |ec_random_nonzero_scalar| or lower, so
|
|
// that all scalars we generate are, by default, secret.
|
|
CONSTTIME_SECRET(k.words, sizeof(k.words));
|
|
|
|
int retry;
|
|
ECDSA_SIG *sig =
|
|
ecdsa_sign_impl(group, &retry, priv_key, &k, digest, digest_len);
|
|
if (sig != NULL || !retry) {
|
|
OPENSSL_cleanse(&k, sizeof(EC_SCALAR));
|
|
return sig;
|
|
}
|
|
|
|
iters++;
|
|
if (iters > kMaxIterations) {
|
|
OPENSSL_cleanse(&k, sizeof(EC_SCALAR));
|
|
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_TOO_MANY_ITERATIONS);
|
|
return NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
// |ECDSA_sign| uses ASN1/CBB functionality, so it was previously placed in
|
|
// crypto/ecdsa_extra/ecdsa_asn1.c. It's now moved within the FIPS boundary for
|
|
// FIPS compliance.
|
|
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->eckey_method && eckey->eckey_method->sign) {
|
|
return eckey->eckey_method->sign(type, digest, (int)digest_len, sig, sig_len,
|
|
NULL, NULL,
|
|
(EC_KEY*) eckey /* cast away const */);
|
|
}
|
|
|
|
int ret = 0;
|
|
ECDSA_SIG *s = ECDSA_do_sign(digest, digest_len, eckey);
|
|
if (s == NULL) {
|
|
*sig_len = 0;
|
|
goto err;
|
|
}
|
|
|
|
CBB cbb;
|
|
CBB_init_fixed(&cbb, sig, ECDSA_size(eckey));
|
|
size_t len;
|
|
if (!ECDSA_SIG_marshal(&cbb, s) ||
|
|
!CBB_finish(&cbb, NULL, &len)) {
|
|
OPENSSL_PUT_ERROR(ECDSA, ECDSA_R_ENCODE_ERROR);
|
|
*sig_len = 0;
|
|
goto err;
|
|
}
|
|
*sig_len = (unsigned)len;
|
|
ret = 1;
|
|
|
|
err:
|
|
ECDSA_SIG_free(s);
|
|
return ret;
|
|
}
|
|
|
|
// |ECDSA_verify| uses ASN1/CBB functionality, so it was previously placed in
|
|
// crypto/evp_extra/ecdsa_asn1.c. It's now moved within the FIPS boundary for
|
|
// FIPS compliance.
|
|
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;
|
|
}
|
|
|
|
ECDSA_SIG *ecdsa_digestsign_no_self_test(const EVP_MD *md, const uint8_t *input,
|
|
size_t in_len, const EC_KEY *eckey,
|
|
const uint8_t *nonce,
|
|
size_t nonce_len) {
|
|
uint8_t digest[EVP_MAX_MD_SIZE];
|
|
unsigned int digest_len = EVP_MAX_MD_SIZE;
|
|
if (!EVP_Digest(input, in_len, digest, &digest_len, md, NULL)) {
|
|
return 0;
|
|
}
|
|
|
|
return ecdsa_sign_with_nonce_for_known_answer_test(digest, digest_len, eckey,
|
|
nonce, nonce_len);
|
|
}
|
|
|
|
int ecdsa_digestverify_no_self_test(const EVP_MD *md, const uint8_t *input,
|
|
size_t in_len, const ECDSA_SIG *sig,
|
|
const EC_KEY *eckey){
|
|
uint8_t digest[EVP_MAX_MD_SIZE];
|
|
unsigned int digest_len = EVP_MAX_MD_SIZE;
|
|
if (!EVP_Digest(input, in_len, digest, &digest_len, md, NULL)) {
|
|
return 0;
|
|
}
|
|
|
|
return ecdsa_do_verify_no_self_test(digest, digest_len, sig, eckey);
|
|
}
|