kexdh.c revision 157016 
1/*
2 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "includes.h"
26RCSID("$OpenBSD: kexdh.c,v 1.20 2005/11/04 05:15:59 djm Exp $");
27
28#include <openssl/evp.h>
29
30#include "buffer.h"
31#include "bufaux.h"
32#include "ssh2.h"
33#include "kex.h"
34
35void
36kex_dh_hash(
37    char *client_version_string,
38    char *server_version_string,
39    char *ckexinit, int ckexinitlen,
40    char *skexinit, int skexinitlen,
41    u_char *serverhostkeyblob, int sbloblen,
42    BIGNUM *client_dh_pub,
43    BIGNUM *server_dh_pub,
44    BIGNUM *shared_secret,
45    u_char **hash, u_int *hashlen)
46{
47	Buffer b;
48	static u_char digest[EVP_MAX_MD_SIZE];
49	const EVP_MD *evp_md = EVP_sha1();
50	EVP_MD_CTX md;
51
52	buffer_init(&b);
53	buffer_put_cstring(&b, client_version_string);
54	buffer_put_cstring(&b, server_version_string);
55
56	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
57	buffer_put_int(&b, ckexinitlen+1);
58	buffer_put_char(&b, SSH2_MSG_KEXINIT);
59	buffer_append(&b, ckexinit, ckexinitlen);
60	buffer_put_int(&b, skexinitlen+1);
61	buffer_put_char(&b, SSH2_MSG_KEXINIT);
62	buffer_append(&b, skexinit, skexinitlen);
63
64	buffer_put_string(&b, serverhostkeyblob, sbloblen);
65	buffer_put_bignum2(&b, client_dh_pub);
66	buffer_put_bignum2(&b, server_dh_pub);
67	buffer_put_bignum2(&b, shared_secret);
68
69#ifdef DEBUG_KEX
70	buffer_dump(&b);
71#endif
72	EVP_DigestInit(&md, evp_md);
73	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
74	EVP_DigestFinal(&md, digest, NULL);
75
76	buffer_free(&b);
77
78#ifdef DEBUG_KEX
79	dump_digest("hash", digest, EVP_MD_size(evp_md));
80#endif
81	*hash = digest;
82	*hashlen = EVP_MD_size(evp_md);
83}
84