kexecdh.c revision 295367 
1/* $OpenBSD: kexecdh.c,v 1.6 2015/01/19 20:16:15 markus Exp $ */
2/*
3 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
4 * Copyright (c) 2010 Damien Miller.  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#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
30
31#include <sys/types.h>
32
33#include <signal.h>
34#include <string.h>
35
36#include <openssl/bn.h>
37#include <openssl/evp.h>
38#include <openssl/ec.h>
39#include <openssl/ecdh.h>
40
41#include "ssh2.h"
42#include "sshkey.h"
43#include "cipher.h"
44#include "kex.h"
45#include "sshbuf.h"
46#include "digest.h"
47#include "ssherr.h"
48
49int
50kex_ecdh_hash(
51    int hash_alg,
52    const EC_GROUP *ec_group,
53    const char *client_version_string,
54    const char *server_version_string,
55    const u_char *ckexinit, size_t ckexinitlen,
56    const u_char *skexinit, size_t skexinitlen,
57    const u_char *serverhostkeyblob, size_t sbloblen,
58    const EC_POINT *client_dh_pub,
59    const EC_POINT *server_dh_pub,
60    const BIGNUM *shared_secret,
61    u_char *hash, size_t *hashlen)
62{
63	struct sshbuf *b;
64	int r;
65
66	if (*hashlen < ssh_digest_bytes(hash_alg))
67		return SSH_ERR_INVALID_ARGUMENT;
68	if ((b = sshbuf_new()) == NULL)
69		return SSH_ERR_ALLOC_FAIL;
70	if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
71	    (r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
72	    /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
73	    (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
74	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
75	    (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
76	    (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
77	    (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
78	    (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
79	    (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
80	    (r = sshbuf_put_ec(b, client_dh_pub, ec_group)) != 0 ||
81	    (r = sshbuf_put_ec(b, server_dh_pub, ec_group)) != 0 ||
82	    (r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
83		sshbuf_free(b);
84		return r;
85	}
86#ifdef DEBUG_KEX
87	sshbuf_dump(b, stderr);
88#endif
89	if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
90		sshbuf_free(b);
91		return SSH_ERR_LIBCRYPTO_ERROR;
92	}
93	sshbuf_free(b);
94	*hashlen = ssh_digest_bytes(hash_alg);
95#ifdef DEBUG_KEX
96	dump_digest("hash", hash, *hashlen);
97#endif
98	return 0;
99}
100#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */
101