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