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 #include <openssl/evp.h>
32 #include <signal.h>
33
34 #include "buffer.h"
35 #include "key.h"
36 #include "cipher.h"
37 #include "kex.h"
38 #include "ssh2.h"
39
40 void
kexgex_hash(const EVP_MD * evp_md,char * client_version_string,char * server_version_string,char * ckexinit,int ckexinitlen,char * skexinit,int skexinitlen,u_char * serverhostkeyblob,int sbloblen,int min,int wantbits,int max,BIGNUM * prime,BIGNUM * gen,BIGNUM * client_dh_pub,BIGNUM * server_dh_pub,BIGNUM * shared_secret,u_char ** hash,u_int * hashlen)41 kexgex_hash(
42 const EVP_MD *evp_md,
43 char *client_version_string,
44 char *server_version_string,
45 char *ckexinit, int ckexinitlen,
46 char *skexinit, int skexinitlen,
47 u_char *serverhostkeyblob, int sbloblen,
48 int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
49 BIGNUM *client_dh_pub,
50 BIGNUM *server_dh_pub,
51 BIGNUM *shared_secret,
52 u_char **hash, u_int *hashlen)
53 {
54 Buffer b;
55 static u_char digest[EVP_MAX_MD_SIZE];
56 EVP_MD_CTX md;
57
58 buffer_init(&b);
59 buffer_put_cstring(&b, client_version_string);
60 buffer_put_cstring(&b, server_version_string);
61
62 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
63 buffer_put_int(&b, ckexinitlen+1);
64 buffer_put_char(&b, SSH2_MSG_KEXINIT);
65 buffer_append(&b, ckexinit, ckexinitlen);
66 buffer_put_int(&b, skexinitlen+1);
67 buffer_put_char(&b, SSH2_MSG_KEXINIT);
68 buffer_append(&b, skexinit, skexinitlen);
69
70 buffer_put_string(&b, serverhostkeyblob, sbloblen);
71 if (min == -1 || max == -1)
72 buffer_put_int(&b, wantbits);
73 else {
74 buffer_put_int(&b, min);
75 buffer_put_int(&b, wantbits);
76 buffer_put_int(&b, max);
77 }
78 buffer_put_bignum2(&b, prime);
79 buffer_put_bignum2(&b, gen);
80 buffer_put_bignum2(&b, client_dh_pub);
81 buffer_put_bignum2(&b, server_dh_pub);
82 buffer_put_bignum2(&b, shared_secret);
83
84 #ifdef DEBUG_KEXDH
85 buffer_dump(&b);
86 #endif
87
88 EVP_DigestInit(&md, evp_md);
89 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
90 EVP_DigestFinal(&md, digest, NULL);
91
92 buffer_free(&b);
93 *hash = digest;
94 *hashlen = EVP_MD_size(evp_md);
95 #ifdef DEBUG_KEXDH
96 dump_digest("hash", digest, *hashlen);
97 #endif
98 }
99