1 /* $OpenBSD: kexc25519c.c,v 1.4 2014/01/12 08:13:13 djm 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 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include <sys/types.h>
46 kexc25519_client(Kex *kex)
49 u_char client_key[CURVE25519_SIZE];
50 u_char client_pubkey[CURVE25519_SIZE];
51 u_char *server_pubkey = NULL;
52 u_char *server_host_key_blob = NULL, *signature = NULL;
54 u_int slen, sbloblen, hashlen;
57 kexc25519_keygen(client_key, client_pubkey);
59 packet_start(SSH2_MSG_KEX_ECDH_INIT);
60 packet_put_string(client_pubkey, sizeof(client_pubkey));
62 debug("sending SSH2_MSG_KEX_ECDH_INIT");
65 dump_digest("client private key:", client_key, sizeof(client_key));
68 debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
69 packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
72 server_host_key_blob = packet_get_string(&sbloblen);
73 server_host_key = key_from_blob(server_host_key_blob, sbloblen);
74 if (server_host_key == NULL)
75 fatal("cannot decode server_host_key_blob");
76 if (server_host_key->type != kex->hostkey_type)
77 fatal("type mismatch for decoded server_host_key_blob");
78 if (kex->verify_host_key == NULL)
79 fatal("cannot verify server_host_key");
80 if (kex->verify_host_key(server_host_key) == -1)
81 fatal("server_host_key verification failed");
83 /* Q_S, server public key */
84 server_pubkey = packet_get_string(&slen);
85 if (slen != CURVE25519_SIZE)
86 fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
89 dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
93 signature = packet_get_string(&slen);
96 buffer_init(&shared_secret);
97 kexc25519_shared_key(client_key, server_pubkey, &shared_secret);
99 /* calc and verify H */
102 kex->client_version_string,
103 kex->server_version_string,
104 buffer_ptr(&kex->my), buffer_len(&kex->my),
105 buffer_ptr(&kex->peer), buffer_len(&kex->peer),
106 server_host_key_blob, sbloblen,
109 buffer_ptr(&shared_secret), buffer_len(&shared_secret),
112 free(server_host_key_blob);
114 if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
115 fatal("key_verify failed for server_host_key");
116 key_free(server_host_key);
119 /* save session id */
120 if (kex->session_id == NULL) {
121 kex->session_id_len = hashlen;
122 kex->session_id = xmalloc(kex->session_id_len);
123 memcpy(kex->session_id, hash, kex->session_id_len);
125 kex_derive_keys(kex, hash, hashlen,
126 buffer_ptr(&shared_secret), buffer_len(&shared_secret));
127 buffer_free(&shared_secret);