dh.c revision 1.5 
1/*	$OpenBSD: dh.c,v 1.5 1999/04/19 20:00:24 niklas Exp $	*/
2/*	$EOM: dh.c,v 1.5 1999/04/17 23:20:22 niklas Exp $	*/
3
4/*
5 * Copyright (c) 1998 Niels Provos.  All rights reserved.
6 * Copyright (c) 1999 Niklas Hallqvist.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by Ericsson Radio Systems.
19 * 4. The name of the author may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34/*
35 * This code was written under funding by Ericsson Radio Systems.
36 */
37
38#include <sys/param.h>
39
40#include "sysdep.h"
41
42#include "math_group.h"
43#include "dh.h"
44#include "log.h"
45
46/*
47 * Returns the length of our exchange value.
48 */
49
50int
51dh_getlen (struct group *group)
52{
53  return group->getlen (group);
54}
55
56/*
57 * Creates the exchange value we are offering to the other party.
58 * Each time this function is called a new value is created, that
59 * means the application has to save the exchange value itself,
60 * dh_create_exchange should only be called once.
61 */
62int
63dh_create_exchange (struct group *group, u_int8_t *buf)
64{
65  if (group->setrandom (group, group->c))
66    return -1;
67  if (group->operation (group, group->a, group->gen, group->c))
68    return -1;
69  group->getraw (group, group->a, buf);
70  return 0;
71}
72
73/*
74 * Creates the Diffie-Hellman shared secret in 'secret', where 'exchange'
75 * is the exchange value offered by the other party. No length verification
76 * is done for the value, the application has to do that.
77 */
78int
79dh_create_shared (struct group *group, u_int8_t *secret, u_int8_t *exchange)
80{
81  if (group->setraw (group, group->b, exchange, group->getlen(group)))
82    return -1;
83  if (group->operation (group, group->a, group->b, group->c))
84    return -1;
85  group->getraw (group, group->a, secret);
86  return 0;
87}
88