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/* $OpenBSD: michael.c,v 1.1 2006/03/21 18:40:54 reyk Exp $ */
/*
* Copyright (c) 2005, 2006 Reyk Floeter <reyk@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Implementation of the Michael MIC as defined in IEEE 802.11i for TKIP.
* The MIC generates a 64bit digest, which shouldn't be used for any other
* applications except TKIP.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <crypto/michael.h>
#define ROL(n, x) (((x) << (n)) | ((x) >> (32 - (n))))
#define ROR(n, x) (((x) >> (n)) | ((x) << (32 - (n))))
#define VAL32(x) (*((u_int32_t *)(x)))
#define XSWAP(x) (((x) & 0xff00ff00UL) >> 8) | ((((x) & 0x00ff00ffUL) << 8))
#define MICHAEL_BLOCK(l, r) do { \
r ^= ROL(17, l); \
l += r; \
r ^= XSWAP(l); \
l += r; \
r ^= ROL(3, l); \
l += r; \
r ^= ROR(2, l); \
l += r; \
} while (0)
void
michael_init(MICHAEL_CTX *ctx)
{
bzero(ctx, sizeof(MICHAEL_CTX));
}
void
michael_update(MICHAEL_CTX *ctx, const u_int8_t *data, u_int len)
{
int i;
for (i = 0; i < len; i++) {
ctx->michael_state |= data[i] << (ctx->michael_count << 3);
ctx->michael_count++;
if (ctx->michael_count >= MICHAEL_RAW_BLOCK_LENGTH) {
ctx->michael_l ^= ctx->michael_state;
MICHAEL_BLOCK(ctx->michael_l, ctx->michael_r);
ctx->michael_state = ctx->michael_count = 0;
}
}
}
void
michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH], MICHAEL_CTX *ctx)
{
u_int8_t pad[] = { 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
michael_update(ctx, pad, sizeof(pad));
VAL32(digest) = letoh32(ctx->michael_l);
VAL32(digest + MICHAEL_RAW_BLOCK_LENGTH) = letoh32(ctx->michael_r);
}
void
michael_key(const u_int8_t *key, MICHAEL_CTX *ctx)
{
ctx->michael_l = ctx->michael_key[0] =
htole32(VAL32(key));
ctx->michael_r = ctx->michael_key[1] =
htole32(VAL32(key + MICHAEL_RAW_BLOCK_LENGTH));
}
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