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openssh-portable/ssh-ecdsa.c

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/* $OpenBSD: ssh-ecdsa.c,v 1.25 2022/10/28 00:44:44 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
* Copyright (c) 2010 Damien Miller. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 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 AUTHOR 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.
*/
#include "includes.h"
#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
#include <sys/types.h>
#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/evp.h>
#include <string.h>
#include "sshbuf.h"
#include "ssherr.h"
#include "digest.h"
#define SSHKEY_INTERNAL
#include "sshkey.h"
#include "openbsd-compat/openssl-compat.h"
static u_int
ssh_ecdsa_size(const struct sshkey *key)
{
switch (key->ecdsa_nid) {
case NID_X9_62_prime256v1:
return 256;
case NID_secp384r1:
return 384;
#ifdef OPENSSL_HAS_NISTP521
case NID_secp521r1:
return 521;
#endif
default:
return 0;
}
}
static void
ssh_ecdsa_cleanup(struct sshkey *k)
{
EC_KEY_free(k->ecdsa);
k->ecdsa = NULL;
}
static int
ssh_ecdsa_equal(const struct sshkey *a, const struct sshkey *b)
{
const EC_GROUP *grp_a, *grp_b;
const EC_POINT *pub_a, *pub_b;
if (a->ecdsa == NULL || b->ecdsa == NULL)
return 0;
if ((grp_a = EC_KEY_get0_group(a->ecdsa)) == NULL ||
(grp_b = EC_KEY_get0_group(b->ecdsa)) == NULL)
return 0;
if ((pub_a = EC_KEY_get0_public_key(a->ecdsa)) == NULL ||
(pub_b = EC_KEY_get0_public_key(b->ecdsa)) == NULL)
return 0;
if (EC_GROUP_cmp(grp_a, grp_b, NULL) != 0)
return 0;
if (EC_POINT_cmp(grp_a, pub_a, pub_b, NULL) != 0)
return 0;
return 1;
}
static int
ssh_ecdsa_serialize_public(const struct sshkey *key, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
int r;
if (key->ecdsa == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_put_cstring(b,
sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
(r = sshbuf_put_eckey(b, key->ecdsa)) != 0)
return r;
return 0;
}
static int
ssh_ecdsa_serialize_private(const struct sshkey *key, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
int r;
if (!sshkey_is_cert(key)) {
if ((r = ssh_ecdsa_serialize_public(key, b, opts)) != 0)
return r;
}
if ((r = sshbuf_put_bignum2(b,
EC_KEY_get0_private_key(key->ecdsa))) != 0)
return r;
return 0;
}
static int
ssh_ecdsa_generate(struct sshkey *k, int bits)
{
EC_KEY *private;
if ((k->ecdsa_nid = sshkey_ecdsa_bits_to_nid(bits)) == -1)
return SSH_ERR_KEY_LENGTH;
if ((private = EC_KEY_new_by_curve_name(k->ecdsa_nid)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if (EC_KEY_generate_key(private) != 1) {
EC_KEY_free(private);
return SSH_ERR_LIBCRYPTO_ERROR;
}
EC_KEY_set_asn1_flag(private, OPENSSL_EC_NAMED_CURVE);
k->ecdsa = private;
return 0;
}
static int
ssh_ecdsa_copy_public(const struct sshkey *from, struct sshkey *to)
{
to->ecdsa_nid = from->ecdsa_nid;
if ((to->ecdsa = EC_KEY_new_by_curve_name(from->ecdsa_nid)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if (EC_KEY_set_public_key(to->ecdsa,
EC_KEY_get0_public_key(from->ecdsa)) != 1)
return SSH_ERR_LIBCRYPTO_ERROR; /* caller will free k->ecdsa */
return 0;
}
static int
ssh_ecdsa_deserialize_public(const char *ktype, struct sshbuf *b,
struct sshkey *key)
{
int r;
char *curve = NULL;
if ((key->ecdsa_nid = sshkey_ecdsa_nid_from_name(ktype)) == -1)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_get_cstring(b, &curve, NULL)) != 0)
goto out;
if (key->ecdsa_nid != sshkey_curve_name_to_nid(curve)) {
r = SSH_ERR_EC_CURVE_MISMATCH;
goto out;
}
EC_KEY_free(key->ecdsa);
key->ecdsa = NULL;
if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
if ((r = sshbuf_get_eckey(b, key->ecdsa)) != 0)
goto out;
if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa),
EC_KEY_get0_public_key(key->ecdsa)) != 0) {
r = SSH_ERR_KEY_INVALID_EC_VALUE;
goto out;
}
/* success */
r = 0;
#ifdef DEBUG_PK
sshkey_dump_ec_point(EC_KEY_get0_group(key->ecdsa),
EC_KEY_get0_public_key(key->ecdsa));
#endif
out:
free(curve);
if (r != 0) {
EC_KEY_free(key->ecdsa);
key->ecdsa = NULL;
}
return r;
}
static int
ssh_ecdsa_deserialize_private(const char *ktype, struct sshbuf *b,
struct sshkey *key)
{
int r;
BIGNUM *exponent = NULL;
if (!sshkey_is_cert(key)) {
if ((r = ssh_ecdsa_deserialize_public(ktype, b, key)) != 0)
return r;
}
if ((r = sshbuf_get_bignum2(b, &exponent)) != 0)
goto out;
if (EC_KEY_set_private_key(key->ecdsa, exponent) != 1) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
if ((r = sshkey_ec_validate_private(key->ecdsa)) != 0)
goto out;
/* success */
r = 0;
out:
BN_clear_free(exponent);
return r;
}
/* ARGSUSED */
static int
ssh_ecdsa_sign(struct sshkey *key,
u_char **sigp, size_t *lenp,
const u_char *data, size_t dlen,
const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
{
ECDSA_SIG *esig = NULL;
const BIGNUM *sig_r, *sig_s;
int hash_alg;
u_char digest[SSH_DIGEST_MAX_LENGTH];
size_t len, hlen;
struct sshbuf *b = NULL, *bb = NULL;
int ret = SSH_ERR_INTERNAL_ERROR;
if (lenp != NULL)
*lenp = 0;
if (sigp != NULL)
*sigp = NULL;
if (key == NULL || key->ecdsa == NULL ||
sshkey_type_plain(key->type) != KEY_ECDSA)
return SSH_ERR_INVALID_ARGUMENT;
if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
(hlen = ssh_digest_bytes(hash_alg)) == 0)
return SSH_ERR_INTERNAL_ERROR;
if ((ret = ssh_digest_memory(hash_alg, data, dlen,
digest, sizeof(digest))) != 0)
goto out;
if ((esig = ECDSA_do_sign(digest, hlen, key->ecdsa)) == NULL) {
ret = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto out;
}
ECDSA_SIG_get0(esig, &sig_r, &sig_s);
if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
(ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
goto out;
if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
(ret = sshbuf_put_stringb(b, bb)) != 0)
goto out;
len = sshbuf_len(b);
if (sigp != NULL) {
if ((*sigp = malloc(len)) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(*sigp, sshbuf_ptr(b), len);
}
if (lenp != NULL)
*lenp = len;
ret = 0;
out:
explicit_bzero(digest, sizeof(digest));
sshbuf_free(b);
sshbuf_free(bb);
ECDSA_SIG_free(esig);
return ret;
}
/* ARGSUSED */
static int
ssh_ecdsa_verify(const struct sshkey *key,
const u_char *sig, size_t siglen,
const u_char *data, size_t dlen, const char *alg, u_int compat,
struct sshkey_sig_details **detailsp)
{
ECDSA_SIG *esig = NULL;
BIGNUM *sig_r = NULL, *sig_s = NULL;
int hash_alg;
u_char digest[SSH_DIGEST_MAX_LENGTH];
size_t hlen;
int ret = SSH_ERR_INTERNAL_ERROR;
struct sshbuf *b = NULL, *sigbuf = NULL;
char *ktype = NULL;
if (key == NULL || key->ecdsa == NULL ||
sshkey_type_plain(key->type) != KEY_ECDSA ||
sig == NULL || siglen == 0)
return SSH_ERR_INVALID_ARGUMENT;
if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
(hlen = ssh_digest_bytes(hash_alg)) == 0)
return SSH_ERR_INTERNAL_ERROR;
/* fetch signature */
if ((b = sshbuf_from(sig, siglen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
sshbuf_froms(b, &sigbuf) != 0) {
ret = SSH_ERR_INVALID_FORMAT;
goto out;
}
if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
ret = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (sshbuf_len(b) != 0) {
ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
goto out;
}
/* parse signature */
if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
ret = SSH_ERR_INVALID_FORMAT;
goto out;
}
if ((esig = ECDSA_SIG_new()) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (!ECDSA_SIG_set0(esig, sig_r, sig_s)) {
ret = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
sig_r = sig_s = NULL; /* transferred */
if (sshbuf_len(sigbuf) != 0) {
ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
goto out;
}
if ((ret = ssh_digest_memory(hash_alg, data, dlen,
digest, sizeof(digest))) != 0)
goto out;
switch (ECDSA_do_verify(digest, hlen, esig, key->ecdsa)) {
case 1:
ret = 0;
break;
case 0:
ret = SSH_ERR_SIGNATURE_INVALID;
goto out;
default:
ret = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
out:
explicit_bzero(digest, sizeof(digest));
sshbuf_free(sigbuf);
sshbuf_free(b);
ECDSA_SIG_free(esig);
BN_clear_free(sig_r);
BN_clear_free(sig_s);
free(ktype);
return ret;
}
/* NB. not static; used by ECDSA-SK */
const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
/* .size = */ ssh_ecdsa_size,
/* .alloc = */ NULL,
/* .cleanup = */ ssh_ecdsa_cleanup,
/* .equal = */ ssh_ecdsa_equal,
/* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
/* .ssh_deserialize_public = */ ssh_ecdsa_deserialize_public,
/* .ssh_serialize_private = */ ssh_ecdsa_serialize_private,
/* .ssh_deserialize_private = */ ssh_ecdsa_deserialize_private,
/* .generate = */ ssh_ecdsa_generate,
/* .copy_public = */ ssh_ecdsa_copy_public,
/* .sign = */ ssh_ecdsa_sign,
/* .verify = */ ssh_ecdsa_verify,
};
const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
/* .name = */ "ecdsa-sha2-nistp256",
/* .shortname = */ "ECDSA",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA,
/* .nid = */ NID_X9_62_prime256v1,
/* .cert = */ 0,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
/* .name = */ "ecdsa-sha2-nistp256-cert-v01@openssh.com",
/* .shortname = */ "ECDSA-CERT",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA_CERT,
/* .nid = */ NID_X9_62_prime256v1,
/* .cert = */ 1,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
/* .name = */ "ecdsa-sha2-nistp384",
/* .shortname = */ "ECDSA",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA,
/* .nid = */ NID_secp384r1,
/* .cert = */ 0,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
/* .name = */ "ecdsa-sha2-nistp384-cert-v01@openssh.com",
/* .shortname = */ "ECDSA-CERT",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA_CERT,
/* .nid = */ NID_secp384r1,
/* .cert = */ 1,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
#ifdef OPENSSL_HAS_NISTP521
const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
/* .name = */ "ecdsa-sha2-nistp521",
/* .shortname = */ "ECDSA",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA,
/* .nid = */ NID_secp521r1,
/* .cert = */ 0,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
/* .name = */ "ecdsa-sha2-nistp521-cert-v01@openssh.com",
/* .shortname = */ "ECDSA-CERT",
/* .sigalg = */ NULL,
/* .type = */ KEY_ECDSA_CERT,
/* .nid = */ NID_secp521r1,
/* .cert = */ 1,
/* .sigonly = */ 0,
/* .keybits = */ 0,
/* .funcs = */ &sshkey_ecdsa_funcs,
};
#endif
#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
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