2 * Michael MIC implementation - optimized for TKIP MIC operations
3 * Copyright 2002-2003, Instant802 Networks, Inc.
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/types.h>
11 #include <linux/bitops.h>
12 #include <asm/unaligned.h>
16 static void michael_block(struct michael_mic_ctx *mctx, u32 val)
19 mctx->r ^= rol32(mctx->l, 17);
21 mctx->r ^= ((mctx->l & 0xff00ff00) >> 8) |
22 ((mctx->l & 0x00ff00ff) << 8);
24 mctx->r ^= rol32(mctx->l, 3);
26 mctx->r ^= ror32(mctx->l, 2);
30 static void michael_mic_hdr(struct michael_mic_ctx *mctx,
31 u8 *key, u8 *da, u8 *sa, u8 priority)
33 mctx->l = get_unaligned_le32(key);
34 mctx->r = get_unaligned_le32(key + 4);
37 * A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
38 * calculation, but it is _not_ transmitted
40 michael_block(mctx, get_unaligned_le32(da));
41 michael_block(mctx, get_unaligned_le16(&da[4]) |
42 (get_unaligned_le16(sa) << 16));
43 michael_block(mctx, get_unaligned_le32(&sa[2]));
44 michael_block(mctx, priority);
47 void michael_mic(u8 *key, u8 *da, u8 *sa, u8 priority,
48 u8 *data, size_t data_len, u8 *mic)
51 size_t block, blocks, left;
52 struct michael_mic_ctx mctx;
54 michael_mic_hdr(&mctx, key, da, sa, priority);
57 blocks = data_len / 4;
60 for (block = 0; block < blocks; block++)
61 michael_block(&mctx, get_unaligned_le32(&data[block * 4]));
63 /* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
64 * total length a multiple of 4. */
69 val |= data[blocks * 4 + left];
72 michael_block(&mctx, val);
73 michael_block(&mctx, 0);
75 put_unaligned_le32(mctx.l, mic);
76 put_unaligned_le32(mctx.r, mic + 4);