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-rw-r--r--ssh-ecdsa.c470
1 files changed, 470 insertions, 0 deletions
diff --git a/ssh-ecdsa.c b/ssh-ecdsa.c
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--- /dev/null
+++ b/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 */