kexdh.c revision 162853 
1/* $OpenBSD: kexdh.c,v 1.23 2006/08/03 03:34:42 deraadt 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#include <sys/types.h>
29
30#include <signal.h>
31
32#include <openssl/evp.h>
33
34#include "buffer.h"
35#include "ssh2.h"
36#include "key.h"
37#include "cipher.h"
38#include "kex.h"
39
40void
41kex_dh_hash(
42    char *client_version_string,
43    char *server_version_string,
44    char *ckexinit, int ckexinitlen,
45    char *skexinit, int skexinitlen,
46    u_char *serverhostkeyblob, int sbloblen,
47    BIGNUM *client_dh_pub,
48    BIGNUM *server_dh_pub,
49    BIGNUM *shared_secret,
50    u_char **hash, u_int *hashlen)
51{
52	Buffer b;
53	static u_char digest[EVP_MAX_MD_SIZE];
54	const EVP_MD *evp_md = EVP_sha1();
55	EVP_MD_CTX md;
56
57	buffer_init(&b);
58	buffer_put_cstring(&b, client_version_string);
59	buffer_put_cstring(&b, server_version_string);
60
61	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
62	buffer_put_int(&b, ckexinitlen+1);
63	buffer_put_char(&b, SSH2_MSG_KEXINIT);
64	buffer_append(&b, ckexinit, ckexinitlen);
65	buffer_put_int(&b, skexinitlen+1);
66	buffer_put_char(&b, SSH2_MSG_KEXINIT);
67	buffer_append(&b, skexinit, skexinitlen);
68
69	buffer_put_string(&b, serverhostkeyblob, sbloblen);
70	buffer_put_bignum2(&b, client_dh_pub);
71	buffer_put_bignum2(&b, server_dh_pub);
72	buffer_put_bignum2(&b, shared_secret);
73
74#ifdef DEBUG_KEX
75	buffer_dump(&b);
76#endif
77	EVP_DigestInit(&md, evp_md);
78	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
79	EVP_DigestFinal(&md, digest, NULL);
80
81	buffer_free(&b);
82
83#ifdef DEBUG_KEX
84	dump_digest("hash", digest, EVP_MD_size(evp_md));
85#endif
86	*hash = digest;
87	*hashlen = EVP_MD_size(evp_md);
88}
89