/* * 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); }