1 /* $OpenBSD: kexecdhc.c,v 1.10 2015/01/26 06:10:03 djm 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
, void *);
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
);
93 EC_KEY_free(client_key
);
98 input_kex_ecdh_reply(int type
, u_int32_t seq
, void *ctxt
)
100 struct ssh
*ssh
= ctxt
;
101 struct kex
*kex
= ssh
->kex
;
102 const EC_GROUP
*group
;
103 EC_POINT
*server_public
= NULL
;
105 BIGNUM
*shared_secret
= NULL
;
106 struct sshkey
*server_host_key
= NULL
;
107 u_char
*server_host_key_blob
= NULL
, *signature
= NULL
;
109 u_char hash
[SSH_DIGEST_MAX_LENGTH
];
110 size_t slen
, sbloblen
;
111 size_t klen
= 0, hashlen
;
114 if (kex
->verify_host_key
== NULL
) {
115 r
= SSH_ERR_INVALID_ARGUMENT
;
118 group
= kex
->ec_group
;
119 client_key
= kex
->ec_client_key
;
122 if ((r
= sshpkt_get_string(ssh
, &server_host_key_blob
,
124 (r
= sshkey_from_blob(server_host_key_blob
, sbloblen
,
125 &server_host_key
)) != 0)
127 if (server_host_key
->type
!= kex
->hostkey_type
||
128 (kex
->hostkey_type
== KEY_ECDSA
&&
129 server_host_key
->ecdsa_nid
!= kex
->hostkey_nid
)) {
130 r
= SSH_ERR_KEY_TYPE_MISMATCH
;
133 if (kex
->verify_host_key(server_host_key
, ssh
) == -1) {
134 r
= SSH_ERR_SIGNATURE_INVALID
;
138 /* Q_S, server public key */
140 if ((server_public
= EC_POINT_new(group
)) == NULL
) {
141 r
= SSH_ERR_ALLOC_FAIL
;
144 if ((r
= sshpkt_get_ec(ssh
, server_public
, group
)) != 0 ||
145 (r
= sshpkt_get_string(ssh
, &signature
, &slen
)) != 0 ||
146 (r
= sshpkt_get_end(ssh
)) != 0)
150 fputs("server public key:\n", stderr
);
151 sshkey_dump_ec_point(group
, server_public
);
153 if (sshkey_ec_validate_public(group
, server_public
) != 0) {
154 sshpkt_disconnect(ssh
, "invalid server public key");
155 r
= SSH_ERR_MESSAGE_INCOMPLETE
;
159 klen
= (EC_GROUP_get_degree(group
) + 7) / 8;
160 if ((kbuf
= malloc(klen
)) == NULL
||
161 (shared_secret
= BN_new()) == NULL
) {
162 r
= SSH_ERR_ALLOC_FAIL
;
165 if (ECDH_compute_key(kbuf
, klen
, server_public
,
166 client_key
, NULL
) != (int)klen
||
167 BN_bin2bn(kbuf
, klen
, shared_secret
) == NULL
) {
168 r
= SSH_ERR_LIBCRYPTO_ERROR
;
173 dump_digest("shared secret", kbuf
, klen
);
175 /* calc and verify H */
176 hashlen
= sizeof(hash
);
177 if ((r
= kex_ecdh_hash(
180 kex
->client_version_string
,
181 kex
->server_version_string
,
182 sshbuf_ptr(kex
->my
), sshbuf_len(kex
->my
),
183 sshbuf_ptr(kex
->peer
), sshbuf_len(kex
->peer
),
184 server_host_key_blob
, sbloblen
,
185 EC_KEY_get0_public_key(client_key
),
188 hash
, &hashlen
)) != 0)
191 if ((r
= sshkey_verify(server_host_key
, signature
, slen
, hash
,
192 hashlen
, ssh
->compat
)) != 0)
195 /* save session id */
196 if (kex
->session_id
== NULL
) {
197 kex
->session_id_len
= hashlen
;
198 kex
->session_id
= malloc(kex
->session_id_len
);
199 if (kex
->session_id
== NULL
) {
200 r
= SSH_ERR_ALLOC_FAIL
;
203 memcpy(kex
->session_id
, hash
, kex
->session_id_len
);
206 if ((r
= kex_derive_keys_bn(ssh
, hash
, hashlen
, shared_secret
)) == 0)
207 r
= kex_send_newkeys(ssh
);
209 explicit_bzero(hash
, sizeof(hash
));
210 if (kex
->ec_client_key
) {
211 EC_KEY_free(kex
->ec_client_key
);
212 kex
->ec_client_key
= NULL
;
215 EC_POINT_clear_free(server_public
);
217 explicit_bzero(kbuf
, klen
);
221 BN_clear_free(shared_secret
);
222 sshkey_free(server_host_key
);
223 free(server_host_key_blob
);
227 #endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */