1 /* $OpenBSD: dh.c,v 1.10 2005/04/08 22:32:09 cloder 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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*
30 * This code was written under funding by Ericsson Radio Systems.
31 */
32
33 #include <sys/param.h>
34
35 #include "math_group.h"
36 #include "dh.h"
37 #include "log.h"
38
39 /*
40 * Returns the length of our exchange value.
41 */
42
43 int
dh_getlen(struct group * group)44 dh_getlen(struct group *group)
45 {
46 return group->getlen(group);
47 }
48
49 /*
50 * Creates the exchange value we are offering to the other party.
51 * Each time this function is called a new value is created, that
52 * means the application has to save the exchange value itself,
53 * dh_create_exchange should only be called once.
54 */
55 int
dh_create_exchange(struct group * group,u_int8_t * buf)56 dh_create_exchange(struct group *group, u_int8_t *buf)
57 {
58 if (group->setrandom(group, group->c))
59 return -1;
60 if (group->operation(group, group->a, group->gen, group->c))
61 return -1;
62 group->getraw(group, group->a, buf);
63 return 0;
64 }
65
66 /*
67 * Creates the Diffie-Hellman shared secret in 'secret', where 'exchange'
68 * is the exchange value offered by the other party. No length verification
69 * is done for the value, the application has to do that.
70 */
71 int
dh_create_shared(struct group * group,u_int8_t * secret,u_int8_t * exchange)72 dh_create_shared(struct group *group, u_int8_t *secret, u_int8_t *exchange)
73 {
74 if (group->setraw(group, group->b, exchange, group->getlen(group)))
75 return -1;
76 if (group->operation(group, group->a, group->b, group->c))
77 return -1;
78 group->getraw(group, group->a, secret);
79 return 0;
80 }
81