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"
26 RCSID("$OpenBSD: kexdh.c,v 1.18 2002/03/18 17:50:31 provos Exp $");
27
28 #pragma ident "%Z%%M% %I% %E% SMI"
29
30 #include <openssl/crypto.h>
31 #include <openssl/bn.h>
32
33 #include "xmalloc.h"
34 #include "buffer.h"
35 #include "bufaux.h"
36 #include "key.h"
37 #include "kex.h"
38 #include "log.h"
39 #include "packet.h"
40 #include "dh.h"
41 #include "ssh2.h"
42
43 u_char *
kex_dh_hash(char * client_version_string,char * server_version_string,char * ckexinit,int ckexinitlen,char * skexinit,int skexinitlen,u_char * serverhostkeyblob,int sbloblen,BIGNUM * client_dh_pub,BIGNUM * server_dh_pub,BIGNUM * shared_secret)44 kex_dh_hash(
45 char *client_version_string,
46 char *server_version_string,
47 char *ckexinit, int ckexinitlen,
48 char *skexinit, int skexinitlen,
49 u_char *serverhostkeyblob, int sbloblen,
50 BIGNUM *client_dh_pub,
51 BIGNUM *server_dh_pub,
52 BIGNUM *shared_secret)
53 {
54 Buffer b;
55 static u_char digest[EVP_MAX_MD_SIZE];
56 const EVP_MD *evp_md = EVP_sha1();
57 EVP_MD_CTX md;
58
59 buffer_init(&b);
60 buffer_put_cstring(&b, client_version_string);
61 buffer_put_cstring(&b, server_version_string);
62
63 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
64 buffer_put_int(&b, ckexinitlen+1);
65 buffer_put_char(&b, SSH2_MSG_KEXINIT);
66 buffer_append(&b, ckexinit, ckexinitlen);
67 buffer_put_int(&b, skexinitlen+1);
68 buffer_put_char(&b, SSH2_MSG_KEXINIT);
69 buffer_append(&b, skexinit, skexinitlen);
70
71 buffer_put_string(&b, serverhostkeyblob, sbloblen);
72 buffer_put_bignum2(&b, client_dh_pub);
73 buffer_put_bignum2(&b, server_dh_pub);
74 buffer_put_bignum2(&b, shared_secret);
75
76 #ifdef DEBUG_KEX
77 buffer_dump(&b);
78 #endif
79 EVP_DigestInit(&md, evp_md);
80 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
81 EVP_DigestFinal(&md, digest, NULL);
82
83 buffer_free(&b);
84
85 #ifdef DEBUG_KEX
86 dump_digest("hash", digest, EVP_MD_size(evp_md));
87 #endif
88 return digest;
89 }
90