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1 /* $OpenBSD: kexdh.c,v 1.26 2016/05/02 10:26:04 djm 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 #ifdef WITH_OPENSSL
29 
30 #include <sys/types.h>
31 
32 #include <signal.h>
33 
34 #include <openssl/evp.h>
35 
36 #include "ssh2.h"
37 #include "sshkey.h"
38 #include "cipher.h"
39 #include "kex.h"
40 #include "ssherr.h"
41 #include "sshbuf.h"
42 #include "digest.h"
43 
44 int
kex_dh_hash(int hash_alg,const char * client_version_string,const char * server_version_string,const u_char * ckexinit,size_t ckexinitlen,const u_char * skexinit,size_t skexinitlen,const u_char * serverhostkeyblob,size_t sbloblen,const BIGNUM * client_dh_pub,const BIGNUM * server_dh_pub,const BIGNUM * shared_secret,u_char * hash,size_t * hashlen)45 kex_dh_hash(
46     int hash_alg,
47     const char *client_version_string,
48     const char *server_version_string,
49     const u_char *ckexinit, size_t ckexinitlen,
50     const u_char *skexinit, size_t skexinitlen,
51     const u_char *serverhostkeyblob, size_t sbloblen,
52     const BIGNUM *client_dh_pub,
53     const BIGNUM *server_dh_pub,
54     const BIGNUM *shared_secret,
55     u_char *hash, size_t *hashlen)
56 {
57 	struct sshbuf *b;
58 	int r;
59 
60 	if (*hashlen < ssh_digest_bytes(hash_alg))
61 		return SSH_ERR_INVALID_ARGUMENT;
62 	if ((b = sshbuf_new()) == NULL)
63 		return SSH_ERR_ALLOC_FAIL;
64 	if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
65 	    (r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
66 	    /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
67 	    (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
68 	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
69 	    (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
70 	    (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
71 	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
72 	    (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
73 	    (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
74 	    (r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 ||
75 	    (r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 ||
76 	    (r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
77 		sshbuf_free(b);
78 		return r;
79 	}
80 #ifdef DEBUG_KEX
81 	sshbuf_dump(b, stderr);
82 #endif
83 	if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
84 		sshbuf_free(b);
85 		return SSH_ERR_LIBCRYPTO_ERROR;
86 	}
87 	sshbuf_free(b);
88 	*hashlen = ssh_digest_bytes(hash_alg);
89 #ifdef DEBUG_KEX
90 	dump_digest("hash", hash, *hashlen);
91 #endif
92 	return 0;
93 }
94 #endif /* WITH_OPENSSL */
95