1/*	$OpenBSD: michael.c,v 1.2 2008/07/21 19:52:45 damien Exp $	*/
2
3/*
4 * Copyright (c) 2005, 2006 Reyk Floeter <reyk@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19/*
20 * Implementation of the Michael MIC as defined in IEEE 802.11i for TKIP.
21 * The MIC generates a 64bit digest, which shouldn't be used for any other
22 * applications except TKIP.
23 */
24
25#include <sys/param.h>
26#include <sys/systm.h>
27
28#include <crypto/michael.h>
29
30#define ROL(n, x)	(((x) << (n)) | ((x) >> (32 - (n))))
31#define ROR(n, x)	(((x) >> (n)) | ((x) << (32 - (n))))
32#define XSWAP(x)	(((x) & 0xff00ff00UL) >> 8 | ((x) & 0x00ff00ffUL) << 8)
33
34#if defined(__STRICT_ALIGNMENT) || _BYTE_ORDER != _LITTLE_ENDIAN
35#define GETLE32(x)	((x)[0] | (x)[1] << 8 | (x)[2] << 16 | (x)[3] << 24)
36#define PUTLE32(x, v)	((x)[0] = (u_int8_t)(v),			\
37			 (x)[1] = (u_int8_t)((v) >> 8),			\
38			 (x)[2] = (u_int8_t)((v) >> 16),		\
39			 (x)[3] = (u_int8_t)((v) >> 24))
40#else
41#define GETLE32(x)	(*((u_int32_t *)(x)))
42#define PUTLE32(x, v)	(*((u_int32_t *)(x)) = (v))
43#endif
44
45#define MICHAEL_BLOCK(l, r) do {					\
46	r ^= ROL(17, l);						\
47	l += r;								\
48	r ^= XSWAP(l);							\
49	l += r;								\
50	r ^= ROL(3, l);							\
51	l += r;								\
52	r ^= ROR(2, l);							\
53	l += r;								\
54} while (0)
55
56void
57michael_init(MICHAEL_CTX *ctx)
58{
59	bzero(ctx, sizeof(MICHAEL_CTX));
60}
61
62void
63michael_update(MICHAEL_CTX *ctx, const u_int8_t *data, u_int len)
64{
65	int i;
66
67	for (i = 0; i < len; i++) {
68		ctx->michael_state |= data[i] << (ctx->michael_count << 3);
69		ctx->michael_count++;
70
71		if (ctx->michael_count >= MICHAEL_RAW_BLOCK_LENGTH) {
72			ctx->michael_l ^= ctx->michael_state;
73			MICHAEL_BLOCK(ctx->michael_l, ctx->michael_r);
74			ctx->michael_state = ctx->michael_count = 0;
75		}
76	}
77}
78
79void
80michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH], MICHAEL_CTX *ctx)
81{
82	static const u_int8_t pad[] =
83	    { 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
84
85	michael_update(ctx, pad, sizeof(pad));
86
87	PUTLE32(digest, ctx->michael_l);
88	PUTLE32(digest + MICHAEL_RAW_BLOCK_LENGTH, ctx->michael_r);
89}
90
91void
92michael_key(const u_int8_t *key, MICHAEL_CTX *ctx)
93{
94	ctx->michael_l = ctx->michael_key[0] =
95	    GETLE32(key);
96	ctx->michael_r = ctx->michael_key[1] =
97	    GETLE32(key + MICHAEL_RAW_BLOCK_LENGTH);
98}
99