kexdh.c revision 323129 
1/* $OpenBSD: kexdh.c,v 1.26 2016/05/02 10:26:04 djm Exp $ */
2/*
3 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
27
28#ifdef WITH_OPENSSL
29
30#include <sys/types.h>
31
32#include <signal.h>
33
34#include <openssl/evp.h>
35
36#include "ssh2.h"
37#include "sshkey.h"
38#include "cipher.h"
39#include "kex.h"
40#include "ssherr.h"
41#include "sshbuf.h"
42#include "digest.h"
43
44int
45kex_dh_hash(
46    int hash_alg,
47    const char *client_version_string,
48    const char *server_version_string,
49    const u_char *ckexinit, size_t ckexinitlen,
50    const u_char *skexinit, size_t skexinitlen,
51    const u_char *serverhostkeyblob, size_t sbloblen,
52    const BIGNUM *client_dh_pub,
53    const BIGNUM *server_dh_pub,
54    const BIGNUM *shared_secret,
55    u_char *hash, size_t *hashlen)
56{
57	struct sshbuf *b;
58	int r;
59
60	if (*hashlen < ssh_digest_bytes(hash_alg))
61		return SSH_ERR_INVALID_ARGUMENT;
62	if ((b = sshbuf_new()) == NULL)
63		return SSH_ERR_ALLOC_FAIL;
64	if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
65	    (r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
66	    /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
67	    (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
68	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
69	    (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
70	    (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
71	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
72	    (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
73	    (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
74	    (r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 ||
75	    (r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 ||
76	    (r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
77		sshbuf_free(b);
78		return r;
79	}
80#ifdef DEBUG_KEX
81	sshbuf_dump(b, stderr);
82#endif
83	if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
84		sshbuf_free(b);
85		return SSH_ERR_LIBCRYPTO_ERROR;
86	}
87	sshbuf_free(b);
88	*hashlen = ssh_digest_bytes(hash_alg);
89#ifdef DEBUG_KEX
90	dump_digest("hash", hash, *hashlen);
91#endif
92	return 0;
93}
94#endif /* WITH_OPENSSL */
95