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/*
* Michael MIC implementation - optimized for TKIP MIC operations
* Copyright 2002-2003, Instant802 Networks, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/types.h>
#include "michael.h"
static inline u32 rotr(u32 val, int bits)
{
return (val >> bits) | (val << (32 - bits));
}
static inline u32 rotl(u32 val, int bits)
{
return (val << bits) | (val >> (32 - bits));
}
static inline u32 xswap(u32 val)
{
return ((val & 0xff00ff00) >> 8) | ((val & 0x00ff00ff) << 8);
}
#define michael_block(l, r) \
do { \
r ^= rotl(l, 17); \
l += r; \
r ^= xswap(l); \
l += r; \
r ^= rotl(l, 3); \
l += r; \
r ^= rotr(l, 2); \
l += r; \
} while (0)
static inline u32 michael_get32(u8 *data)
{
return data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
}
static inline void michael_put32(u32 val, u8 *data)
{
data[0] = val & 0xff;
data[1] = (val >> 8) & 0xff;
data[2] = (val >> 16) & 0xff;
data[3] = (val >> 24) & 0xff;
}
void michael_mic(u8 *key, u8 *da, u8 *sa, u8 priority,
u8 *data, size_t data_len, u8 *mic)
{
u32 l, r, val;
size_t block, blocks, left;
l = michael_get32(key);
r = michael_get32(key + 4);
/* A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
* calculation, but it is _not_ transmitted */
l ^= michael_get32(da);
michael_block(l, r);
l ^= da[4] | (da[5] << 8) | (sa[0] << 16) | (sa[1] << 24);
michael_block(l, r);
l ^= michael_get32(&sa[2]);
michael_block(l, r);
l ^= priority;
michael_block(l, r);
/* Real data */
blocks = data_len / 4;
left = data_len % 4;
for (block = 0; block < blocks; block++) {
l ^= michael_get32(&data[block * 4]);
michael_block(l, r);
}
/* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
* total length a multiple of 4. */
val = 0x5a;
while (left > 0) {
val <<= 8;
left--;
val |= data[blocks * 4 + left];
}
l ^= val;
michael_block(l, r);
/* last block is zero, so l ^ 0 = l */
michael_block(l, r);
michael_put32(l, mic);
michael_put32(r, mic + 4);
}
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