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
40 void
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,u_char ** hash,u_int * hashlen)41 kex_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