1/* $OpenBSD: kexgex.c,v 1.27 2006/08/03 03:34:42 deraadt Exp $ */
2/*
3 * Copyright (c) 2000 Niels Provos.  All rights reserved.
4 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
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.
14 *
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.
25 */
26
27#include "includes.h"
28
29#include <sys/types.h>
30
31#ifdef __APPLE_CRYPTO__
32#include "ossl-evp.h"
33#else
34#include <openssl/evp.h>
35#endif
36
37#include <signal.h>
38
39#include "buffer.h"
40#include "key.h"
41#include "cipher.h"
42#include "kex.h"
43#include "ssh2.h"
44
45void
46kexgex_hash(
47    const EVP_MD *evp_md,
48    char *client_version_string,
49    char *server_version_string,
50    char *ckexinit, int ckexinitlen,
51    char *skexinit, int skexinitlen,
52    u_char *serverhostkeyblob, int sbloblen,
53    int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
54    BIGNUM *client_dh_pub,
55    BIGNUM *server_dh_pub,
56    BIGNUM *shared_secret,
57    u_char **hash, u_int *hashlen)
58{
59	Buffer b;
60	static u_char digest[EVP_MAX_MD_SIZE];
61	EVP_MD_CTX md;
62
63	buffer_init(&b);
64	buffer_put_cstring(&b, client_version_string);
65	buffer_put_cstring(&b, server_version_string);
66
67	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
68	buffer_put_int(&b, ckexinitlen+1);
69	buffer_put_char(&b, SSH2_MSG_KEXINIT);
70	buffer_append(&b, ckexinit, ckexinitlen);
71	buffer_put_int(&b, skexinitlen+1);
72	buffer_put_char(&b, SSH2_MSG_KEXINIT);
73	buffer_append(&b, skexinit, skexinitlen);
74
75	buffer_put_string(&b, serverhostkeyblob, sbloblen);
76	if (min == -1 || max == -1)
77		buffer_put_int(&b, wantbits);
78	else {
79		buffer_put_int(&b, min);
80		buffer_put_int(&b, wantbits);
81		buffer_put_int(&b, max);
82	}
83	buffer_put_bignum2(&b, prime);
84	buffer_put_bignum2(&b, gen);
85	buffer_put_bignum2(&b, client_dh_pub);
86	buffer_put_bignum2(&b, server_dh_pub);
87	buffer_put_bignum2(&b, shared_secret);
88
89#ifdef DEBUG_KEXDH
90	buffer_dump(&b);
91#endif
92
93	EVP_DigestInit(&md, evp_md);
94	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
95	EVP_DigestFinal(&md, digest, NULL);
96
97	buffer_free(&b);
98	*hash = digest;
99	*hashlen = EVP_MD_size(evp_md);
100#ifdef DEBUG_KEXDH
101	dump_digest("hash", digest, *hashlen);
102#endif
103}
104