1 /* $OpenBSD: kexecdhc.c,v 1.13 2018/02/07 02:06:51 jsing Exp $ */
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
4 * Copyright (c) 2010 Damien Miller. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
31 #include <sys/types.h>
37 #include <openssl/ecdh.h>
52 static int input_kex_ecdh_reply(int, u_int32_t, struct ssh *);
55 kexecdh_client(struct ssh *ssh)
57 struct kex *kex = ssh->kex;
58 EC_KEY *client_key = NULL;
59 const EC_GROUP *group;
60 const EC_POINT *public_key;
63 if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
64 r = SSH_ERR_ALLOC_FAIL;
67 if (EC_KEY_generate_key(client_key) != 1) {
68 r = SSH_ERR_LIBCRYPTO_ERROR;
71 group = EC_KEY_get0_group(client_key);
72 public_key = EC_KEY_get0_public_key(client_key);
74 if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
75 (r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
76 (r = sshpkt_send(ssh)) != 0)
78 debug("sending SSH2_MSG_KEX_ECDH_INIT");
81 fputs("client private key:\n", stderr);
82 sshkey_dump_ec_key(client_key);
84 kex->ec_client_key = client_key;
85 kex->ec_group = group;
86 client_key = NULL; /* owned by the kex */
88 debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
89 ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_ecdh_reply);
92 EC_KEY_free(client_key);
97 input_kex_ecdh_reply(int type, u_int32_t seq, struct ssh *ssh)
99 struct kex *kex = ssh->kex;
100 const EC_GROUP *group;
101 EC_POINT *server_public = NULL;
103 BIGNUM *shared_secret = NULL;
104 struct sshkey *server_host_key = NULL;
105 u_char *server_host_key_blob = NULL, *signature = NULL;
107 u_char hash[SSH_DIGEST_MAX_LENGTH];
108 size_t slen, sbloblen;
109 size_t klen = 0, hashlen;
112 if (kex->verify_host_key == NULL) {
113 r = SSH_ERR_INVALID_ARGUMENT;
116 group = kex->ec_group;
117 client_key = kex->ec_client_key;
120 if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
122 (r = sshkey_from_blob(server_host_key_blob, sbloblen,
123 &server_host_key)) != 0)
125 if (server_host_key->type != kex->hostkey_type ||
126 (kex->hostkey_type == KEY_ECDSA &&
127 server_host_key->ecdsa_nid != kex->hostkey_nid)) {
128 r = SSH_ERR_KEY_TYPE_MISMATCH;
131 if (kex->verify_host_key(server_host_key, ssh) == -1) {
132 r = SSH_ERR_SIGNATURE_INVALID;
136 /* Q_S, server public key */
138 if ((server_public = EC_POINT_new(group)) == NULL) {
139 r = SSH_ERR_ALLOC_FAIL;
142 if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 ||
143 (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
144 (r = sshpkt_get_end(ssh)) != 0)
148 fputs("server public key:\n", stderr);
149 sshkey_dump_ec_point(group, server_public);
151 if (sshkey_ec_validate_public(group, server_public) != 0) {
152 sshpkt_disconnect(ssh, "invalid server public key");
153 r = SSH_ERR_MESSAGE_INCOMPLETE;
157 klen = (EC_GROUP_get_degree(group) + 7) / 8;
158 if ((kbuf = malloc(klen)) == NULL ||
159 (shared_secret = BN_new()) == NULL) {
160 r = SSH_ERR_ALLOC_FAIL;
163 if (ECDH_compute_key(kbuf, klen, server_public,
164 client_key, NULL) != (int)klen ||
165 BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
166 r = SSH_ERR_LIBCRYPTO_ERROR;
171 dump_digest("shared secret", kbuf, klen);
173 /* calc and verify H */
174 hashlen = sizeof(hash);
175 if ((r = kex_ecdh_hash(
178 kex->client_version_string,
179 kex->server_version_string,
180 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
181 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
182 server_host_key_blob, sbloblen,
183 EC_KEY_get0_public_key(client_key),
186 hash, &hashlen)) != 0)
189 if ((r = sshkey_verify(server_host_key, signature, slen, hash,
190 hashlen, kex->hostkey_alg, ssh->compat)) != 0)
193 /* save session id */
194 if (kex->session_id == NULL) {
195 kex->session_id_len = hashlen;
196 kex->session_id = malloc(kex->session_id_len);
197 if (kex->session_id == NULL) {
198 r = SSH_ERR_ALLOC_FAIL;
201 memcpy(kex->session_id, hash, kex->session_id_len);
204 if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
205 r = kex_send_newkeys(ssh);
207 explicit_bzero(hash, sizeof(hash));
208 EC_KEY_free(kex->ec_client_key);
209 kex->ec_client_key = NULL;
210 EC_POINT_clear_free(server_public);
212 explicit_bzero(kbuf, klen);
215 BN_clear_free(shared_secret);
216 sshkey_free(server_host_key);
217 free(server_host_key_blob);
221 #endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */