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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Cryptographic API
3 *
4 * Michael MIC (IEEE 802.11i/TKIP) keyed digest
5 *
6 * Copyright (c) 2004 Jouni Malinen <jkmaline@cc.hut.fi>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
Herbert Xu06ace7a2005-10-30 21:25:15 +110013#include <asm/byteorder.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/init.h>
15#include <linux/module.h>
16#include <linux/string.h>
17#include <linux/crypto.h>
Herbert Xu06ace7a2005-10-30 21:25:15 +110018#include <linux/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
20
21struct michael_mic_ctx {
22 u8 pending[4];
23 size_t pending_len;
24
25 u32 l, r;
26};
27
28
29static inline u32 xswap(u32 val)
30{
31 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
32}
33
34
35#define michael_block(l, r) \
36do { \
37 r ^= rol32(l, 17); \
38 l += r; \
39 r ^= xswap(l); \
40 l += r; \
41 r ^= rol32(l, 3); \
42 l += r; \
43 r ^= ror32(l, 2); \
44 l += r; \
45} while (0)
46
47
Herbert Xu6c2bb982006-05-16 22:09:29 +100048static void michael_init(struct crypto_tfm *tfm)
Linus Torvalds1da177e2005-04-16 15:20:36 -070049{
Herbert Xu6c2bb982006-05-16 22:09:29 +100050 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 mctx->pending_len = 0;
52}
53
54
Herbert Xu6c2bb982006-05-16 22:09:29 +100055static void michael_update(struct crypto_tfm *tfm, const u8 *data,
56 unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -070057{
Herbert Xu6c2bb982006-05-16 22:09:29 +100058 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
Herbert Xu06ace7a2005-10-30 21:25:15 +110059 const __le32 *src;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61 if (mctx->pending_len) {
62 int flen = 4 - mctx->pending_len;
63 if (flen > len)
64 flen = len;
65 memcpy(&mctx->pending[mctx->pending_len], data, flen);
66 mctx->pending_len += flen;
67 data += flen;
68 len -= flen;
69
70 if (mctx->pending_len < 4)
71 return;
72
Herbert Xu06ace7a2005-10-30 21:25:15 +110073 src = (const __le32 *)mctx->pending;
74 mctx->l ^= le32_to_cpup(src);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 michael_block(mctx->l, mctx->r);
76 mctx->pending_len = 0;
77 }
78
Herbert Xu06ace7a2005-10-30 21:25:15 +110079 src = (const __le32 *)data;
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 while (len >= 4) {
Herbert Xu06ace7a2005-10-30 21:25:15 +110082 mctx->l ^= le32_to_cpup(src++);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 michael_block(mctx->l, mctx->r);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 len -= 4;
85 }
86
87 if (len > 0) {
88 mctx->pending_len = len;
Herbert Xu06ace7a2005-10-30 21:25:15 +110089 memcpy(mctx->pending, src, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 }
91}
92
93
Herbert Xu6c2bb982006-05-16 22:09:29 +100094static void michael_final(struct crypto_tfm *tfm, u8 *out)
Linus Torvalds1da177e2005-04-16 15:20:36 -070095{
Herbert Xu6c2bb982006-05-16 22:09:29 +100096 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 u8 *data = mctx->pending;
Herbert Xu06ace7a2005-10-30 21:25:15 +110098 __le32 *dst = (__le32 *)out;
Linus Torvalds1da177e2005-04-16 15:20:36 -070099
100 /* Last block and padding (0x5a, 4..7 x 0) */
101 switch (mctx->pending_len) {
102 case 0:
103 mctx->l ^= 0x5a;
104 break;
105 case 1:
106 mctx->l ^= data[0] | 0x5a00;
107 break;
108 case 2:
109 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
110 break;
111 case 3:
112 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
113 0x5a000000;
114 break;
115 }
116 michael_block(mctx->l, mctx->r);
117 /* l ^= 0; */
118 michael_block(mctx->l, mctx->r);
119
Herbert Xu06ace7a2005-10-30 21:25:15 +1100120 dst[0] = cpu_to_le32(mctx->l);
121 dst[1] = cpu_to_le32(mctx->r);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122}
123
124
Herbert Xu6c2bb982006-05-16 22:09:29 +1000125static int michael_setkey(struct crypto_tfm *tfm, const u8 *key,
126 unsigned int keylen, u32 *flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127{
Herbert Xu6c2bb982006-05-16 22:09:29 +1000128 struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
Herbert Xu06ace7a2005-10-30 21:25:15 +1100129 const __le32 *data = (const __le32 *)key;
130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 if (keylen != 8) {
132 if (flags)
133 *flags = CRYPTO_TFM_RES_BAD_KEY_LEN;
134 return -EINVAL;
135 }
Herbert Xu06ace7a2005-10-30 21:25:15 +1100136
137 mctx->l = le32_to_cpu(data[0]);
138 mctx->r = le32_to_cpu(data[1]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 return 0;
140}
141
142
143static struct crypto_alg michael_mic_alg = {
144 .cra_name = "michael_mic",
145 .cra_flags = CRYPTO_ALG_TYPE_DIGEST,
146 .cra_blocksize = 8,
147 .cra_ctxsize = sizeof(struct michael_mic_ctx),
148 .cra_module = THIS_MODULE,
Atsushi Nemotoe1147d82006-04-10 08:42:35 +1000149 .cra_alignmask = 3,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list),
151 .cra_u = { .digest = {
152 .dia_digestsize = 8,
153 .dia_init = michael_init,
154 .dia_update = michael_update,
155 .dia_final = michael_final,
156 .dia_setkey = michael_setkey } }
157};
158
159
160static int __init michael_mic_init(void)
161{
162 return crypto_register_alg(&michael_mic_alg);
163}
164
165
166static void __exit michael_mic_exit(void)
167{
168 crypto_unregister_alg(&michael_mic_alg);
169}
170
171
172module_init(michael_mic_init);
173module_exit(michael_mic_exit);
174
175MODULE_LICENSE("GPL v2");
176MODULE_DESCRIPTION("Michael MIC");
177MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>");