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/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
* project 2000. */
/* ====================================================================
* Copyright (c) 2000-2005 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
* licensing@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/dsa.h>
#include <assert.h>
#include <openssl/bn.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "internal.h"
#include "../bytestring/internal.h"
// This function is in dsa_asn1.c rather than dsa.c because it is reachable from
// |EVP_PKEY| parsers. This makes it easier for the static linker to drop most
// of the DSA implementation.
int dsa_check_key(const DSA *dsa) {
if (!dsa->p || !dsa->q || !dsa->g) {
OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS);
return 0;
}
// Fully checking for invalid DSA groups is expensive, so security and
// correctness of the signature scheme depend on how |dsa| was computed. I.e.
// we leave "assurance of domain parameter validity" from FIPS 186-4 to the
// caller. However, we check bounds on all values to avoid DoS vectors even
// when domain parameters are invalid. In particular, signing will infinite
// loop if |g| is zero.
if (BN_is_negative(dsa->p) || BN_is_negative(dsa->q) || BN_is_zero(dsa->p) ||
BN_is_zero(dsa->q) || !BN_is_odd(dsa->p) || !BN_is_odd(dsa->q) ||
// |q| must be a prime divisor of |p - 1|, which implies |q < p|.
BN_cmp(dsa->q, dsa->p) >= 0 ||
// |g| is in the multiplicative group of |p|.
BN_is_negative(dsa->g) || BN_is_zero(dsa->g) ||
BN_cmp(dsa->g, dsa->p) >= 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_INVALID_PARAMETERS);
return 0;
}
// FIPS 186-4 allows only three different sizes for q.
unsigned q_bits = BN_num_bits(dsa->q);
if (q_bits != 160 && q_bits != 224 && q_bits != 256) {
OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_Q_VALUE);
return 0;
}
// Bound |dsa->p| to avoid a DoS vector. Note this limit is much larger than
// the one in FIPS 186-4, which only allows L = 1024, 2048, and 3072.
if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
OPENSSL_PUT_ERROR(DSA, DSA_R_MODULUS_TOO_LARGE);
return 0;
}
if (dsa->pub_key != NULL) {
// The public key is also in the multiplicative group of |p|.
if (BN_is_negative(dsa->pub_key) || BN_is_zero(dsa->pub_key) ||
BN_cmp(dsa->pub_key, dsa->p) >= 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_INVALID_PARAMETERS);
return 0;
}
}
if (dsa->priv_key != NULL) {
// The private key is a non-zero element of the scalar field, determined by
// |q|.
if (BN_is_negative(dsa->priv_key) ||
constant_time_declassify_int(BN_is_zero(dsa->priv_key)) ||
constant_time_declassify_int(BN_cmp(dsa->priv_key, dsa->q) >= 0)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_INVALID_PARAMETERS);
return 0;
}
}
return 1;
}
static int parse_integer(CBS *cbs, BIGNUM **out) {
assert(*out == NULL);
*out = BN_new();
if (*out == NULL) {
return 0;
}
return BN_parse_asn1_unsigned(cbs, *out);
}
static int marshal_integer(CBB *cbb, BIGNUM *bn) {
if (bn == NULL) {
// A DSA object may be missing some components.
OPENSSL_PUT_ERROR(DSA, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
return BN_marshal_asn1(cbb, bn);
}
DSA_SIG *DSA_SIG_parse(CBS *cbs) {
DSA_SIG *ret = DSA_SIG_new();
if (ret == NULL) {
return NULL;
}
CBS child;
if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
!parse_integer(&child, &ret->r) ||
!parse_integer(&child, &ret->s) ||
CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
DSA_SIG_free(ret);
return NULL;
}
return ret;
}
int DSA_SIG_marshal(CBB *cbb, const DSA_SIG *sig) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
!marshal_integer(&child, sig->r) ||
!marshal_integer(&child, sig->s) ||
!CBB_flush(cbb)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
return 0;
}
return 1;
}
DSA *DSA_parse_public_key(CBS *cbs) {
DSA *ret = DSA_new();
if (ret == NULL) {
return NULL;
}
CBS child;
if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
!parse_integer(&child, &ret->pub_key) ||
!parse_integer(&child, &ret->p) ||
!parse_integer(&child, &ret->q) ||
!parse_integer(&child, &ret->g) ||
CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
goto err;
}
if (!dsa_check_key(ret)) {
goto err;
}
return ret;
err:
DSA_free(ret);
return NULL;
}
int DSA_marshal_public_key(CBB *cbb, const DSA *dsa) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
!marshal_integer(&child, dsa->pub_key) ||
!marshal_integer(&child, dsa->p) ||
!marshal_integer(&child, dsa->q) ||
!marshal_integer(&child, dsa->g) ||
!CBB_flush(cbb)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
return 0;
}
return 1;
}
DSA *DSA_parse_parameters(CBS *cbs) {
DSA *ret = DSA_new();
if (ret == NULL) {
return NULL;
}
CBS child;
if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
!parse_integer(&child, &ret->p) ||
!parse_integer(&child, &ret->q) ||
!parse_integer(&child, &ret->g) ||
CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
goto err;
}
if (!dsa_check_key(ret)) {
goto err;
}
return ret;
err:
DSA_free(ret);
return NULL;
}
int DSA_marshal_parameters(CBB *cbb, const DSA *dsa) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
!marshal_integer(&child, dsa->p) ||
!marshal_integer(&child, dsa->q) ||
!marshal_integer(&child, dsa->g) ||
!CBB_flush(cbb)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
return 0;
}
return 1;
}
DSA *DSA_parse_private_key(CBS *cbs) {
DSA *ret = DSA_new();
if (ret == NULL) {
return NULL;
}
CBS child;
uint64_t version;
if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
!CBS_get_asn1_uint64(&child, &version)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
goto err;
}
if (version != 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_VERSION);
goto err;
}
if (!parse_integer(&child, &ret->p) ||
!parse_integer(&child, &ret->q) ||
!parse_integer(&child, &ret->g) ||
!parse_integer(&child, &ret->pub_key) ||
!parse_integer(&child, &ret->priv_key) ||
CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
goto err;
}
if (!dsa_check_key(ret)) {
goto err;
}
return ret;
err:
DSA_free(ret);
return NULL;
}
int DSA_marshal_private_key(CBB *cbb, const DSA *dsa) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
!CBB_add_asn1_uint64(&child, 0 /* version */) ||
!marshal_integer(&child, dsa->p) ||
!marshal_integer(&child, dsa->q) ||
!marshal_integer(&child, dsa->g) ||
!marshal_integer(&child, dsa->pub_key) ||
!marshal_integer(&child, dsa->priv_key) ||
!CBB_flush(cbb)) {
OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
return 0;
}
return 1;
}
DSA_SIG *d2i_DSA_SIG(DSA_SIG **out_sig, const uint8_t **inp, long len) {
if (len < 0) {
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
DSA_SIG *ret = DSA_SIG_parse(&cbs);
if (ret == NULL) {
return NULL;
}
if (out_sig != NULL) {
DSA_SIG_free(*out_sig);
*out_sig = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_DSA_SIG(const DSA_SIG *in, uint8_t **outp) {
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!DSA_SIG_marshal(&cbb, in)) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}
DSA *d2i_DSAPublicKey(DSA **out, const uint8_t **inp, long len) {
if (len < 0) {
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
DSA *ret = DSA_parse_public_key(&cbs);
if (ret == NULL) {
return NULL;
}
if (out != NULL) {
DSA_free(*out);
*out = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_DSAPublicKey(const DSA *in, uint8_t **outp) {
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!DSA_marshal_public_key(&cbb, in)) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}
DSA *d2i_DSAPrivateKey(DSA **out, const uint8_t **inp, long len) {
if (len < 0) {
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
DSA *ret = DSA_parse_private_key(&cbs);
if (ret == NULL) {
return NULL;
}
if (out != NULL) {
DSA_free(*out);
*out = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_DSAPrivateKey(const DSA *in, uint8_t **outp) {
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!DSA_marshal_private_key(&cbb, in)) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}
DSA *d2i_DSAparams(DSA **out, const uint8_t **inp, long len) {
if (len < 0) {
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
DSA *ret = DSA_parse_parameters(&cbs);
if (ret == NULL) {
return NULL;
}
if (out != NULL) {
DSA_free(*out);
*out = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_DSAparams(const DSA *in, uint8_t **outp) {
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!DSA_marshal_parameters(&cbb, in)) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}