1 /* $OpenBSD: kexc25519s.c,v 1.10 2015/12/04 16:41:28 markus Exp $ */
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
4 * Copyright (c) 2010 Damien Miller. All rights reserved.
5 * Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
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 #include <sys/types.h>
44 static int input_kex_c25519_init(int, u_int32_t
, void *);
47 kexc25519_server(struct ssh
*ssh
)
49 debug("expecting SSH2_MSG_KEX_ECDH_INIT");
50 ssh_dispatch_set(ssh
, SSH2_MSG_KEX_ECDH_INIT
, &input_kex_c25519_init
);
55 input_kex_c25519_init(int type
, u_int32_t seq
, void *ctxt
)
57 struct ssh
*ssh
= ctxt
;
58 struct kex
*kex
= ssh
->kex
;
59 struct sshkey
*server_host_private
, *server_host_public
;
60 struct sshbuf
*shared_secret
= NULL
;
61 u_char
*server_host_key_blob
= NULL
, *signature
= NULL
;
62 u_char server_key
[CURVE25519_SIZE
];
63 u_char
*client_pubkey
= NULL
;
64 u_char server_pubkey
[CURVE25519_SIZE
];
65 u_char hash
[SSH_DIGEST_MAX_LENGTH
];
66 size_t slen
, pklen
, sbloblen
, hashlen
;
69 /* generate private key */
70 kexc25519_keygen(server_key
, server_pubkey
);
72 dump_digest("server private key:", server_key
, sizeof(server_key
));
74 if (kex
->load_host_public_key
== NULL
||
75 kex
->load_host_private_key
== NULL
) {
76 r
= SSH_ERR_INVALID_ARGUMENT
;
79 server_host_public
= kex
->load_host_public_key(kex
->hostkey_type
,
80 kex
->hostkey_nid
, ssh
);
81 server_host_private
= kex
->load_host_private_key(kex
->hostkey_type
,
82 kex
->hostkey_nid
, ssh
);
83 if (server_host_public
== NULL
) {
84 r
= SSH_ERR_NO_HOSTKEY_LOADED
;
88 if ((r
= sshpkt_get_string(ssh
, &client_pubkey
, &pklen
)) != 0 ||
89 (r
= sshpkt_get_end(ssh
)) != 0)
91 if (pklen
!= CURVE25519_SIZE
) {
92 r
= SSH_ERR_SIGNATURE_INVALID
;
96 dump_digest("client public key:", client_pubkey
, CURVE25519_SIZE
);
99 if ((shared_secret
= sshbuf_new()) == NULL
) {
100 r
= SSH_ERR_ALLOC_FAIL
;
103 if ((r
= kexc25519_shared_key(server_key
, client_pubkey
,
108 if ((r
= sshkey_to_blob(server_host_public
, &server_host_key_blob
,
111 hashlen
= sizeof(hash
);
112 if ((r
= kex_c25519_hash(
114 kex
->client_version_string
,
115 kex
->server_version_string
,
116 sshbuf_ptr(kex
->peer
), sshbuf_len(kex
->peer
),
117 sshbuf_ptr(kex
->my
), sshbuf_len(kex
->my
),
118 server_host_key_blob
, sbloblen
,
121 sshbuf_ptr(shared_secret
), sshbuf_len(shared_secret
),
122 hash
, &hashlen
)) < 0)
125 /* save session id := H */
126 if (kex
->session_id
== NULL
) {
127 kex
->session_id_len
= hashlen
;
128 kex
->session_id
= malloc(kex
->session_id_len
);
129 if (kex
->session_id
== NULL
) {
130 r
= SSH_ERR_ALLOC_FAIL
;
133 memcpy(kex
->session_id
, hash
, kex
->session_id_len
);
137 if ((r
= kex
->sign(server_host_private
, server_host_public
, &signature
,
138 &slen
, hash
, hashlen
, kex
->hostkey_alg
, ssh
->compat
)) < 0)
141 /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
142 if ((r
= sshpkt_start(ssh
, SSH2_MSG_KEX_ECDH_REPLY
)) != 0 ||
143 (r
= sshpkt_put_string(ssh
, server_host_key_blob
, sbloblen
)) != 0 ||
144 (r
= sshpkt_put_string(ssh
, server_pubkey
, sizeof(server_pubkey
))) != 0 ||
145 (r
= sshpkt_put_string(ssh
, signature
, slen
)) != 0 ||
146 (r
= sshpkt_send(ssh
)) != 0)
149 if ((r
= kex_derive_keys(ssh
, hash
, hashlen
, shared_secret
)) == 0)
150 r
= kex_send_newkeys(ssh
);
152 explicit_bzero(hash
, sizeof(hash
));
153 explicit_bzero(server_key
, sizeof(server_key
));
154 free(server_host_key_blob
);
157 sshbuf_free(shared_secret
);