Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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 | ||
13 | #include <linux/init.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/string.h> | |
16 | #include <linux/crypto.h> | |
17 | ||
18 | ||
19 | struct michael_mic_ctx { | |
20 | u8 pending[4]; | |
21 | size_t pending_len; | |
22 | ||
23 | u32 l, r; | |
24 | }; | |
25 | ||
26 | ||
27 | static inline u32 xswap(u32 val) | |
28 | { | |
29 | return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); | |
30 | } | |
31 | ||
32 | ||
33 | #define michael_block(l, r) \ | |
34 | do { \ | |
35 | r ^= rol32(l, 17); \ | |
36 | l += r; \ | |
37 | r ^= xswap(l); \ | |
38 | l += r; \ | |
39 | r ^= rol32(l, 3); \ | |
40 | l += r; \ | |
41 | r ^= ror32(l, 2); \ | |
42 | l += r; \ | |
43 | } while (0) | |
44 | ||
45 | ||
46 | static inline u32 get_le32(const u8 *p) | |
47 | { | |
48 | return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24); | |
49 | } | |
50 | ||
51 | ||
52 | static inline void put_le32(u8 *p, u32 v) | |
53 | { | |
54 | p[0] = v; | |
55 | p[1] = v >> 8; | |
56 | p[2] = v >> 16; | |
57 | p[3] = v >> 24; | |
58 | } | |
59 | ||
60 | ||
61 | static void michael_init(void *ctx) | |
62 | { | |
63 | struct michael_mic_ctx *mctx = ctx; | |
64 | mctx->pending_len = 0; | |
65 | } | |
66 | ||
67 | ||
68 | static void michael_update(void *ctx, const u8 *data, unsigned int len) | |
69 | { | |
70 | struct michael_mic_ctx *mctx = ctx; | |
71 | ||
72 | if (mctx->pending_len) { | |
73 | int flen = 4 - mctx->pending_len; | |
74 | if (flen > len) | |
75 | flen = len; | |
76 | memcpy(&mctx->pending[mctx->pending_len], data, flen); | |
77 | mctx->pending_len += flen; | |
78 | data += flen; | |
79 | len -= flen; | |
80 | ||
81 | if (mctx->pending_len < 4) | |
82 | return; | |
83 | ||
84 | mctx->l ^= get_le32(mctx->pending); | |
85 | michael_block(mctx->l, mctx->r); | |
86 | mctx->pending_len = 0; | |
87 | } | |
88 | ||
89 | while (len >= 4) { | |
90 | mctx->l ^= get_le32(data); | |
91 | michael_block(mctx->l, mctx->r); | |
92 | data += 4; | |
93 | len -= 4; | |
94 | } | |
95 | ||
96 | if (len > 0) { | |
97 | mctx->pending_len = len; | |
98 | memcpy(mctx->pending, data, len); | |
99 | } | |
100 | } | |
101 | ||
102 | ||
103 | static void michael_final(void *ctx, u8 *out) | |
104 | { | |
105 | struct michael_mic_ctx *mctx = ctx; | |
106 | u8 *data = mctx->pending; | |
107 | ||
108 | /* Last block and padding (0x5a, 4..7 x 0) */ | |
109 | switch (mctx->pending_len) { | |
110 | case 0: | |
111 | mctx->l ^= 0x5a; | |
112 | break; | |
113 | case 1: | |
114 | mctx->l ^= data[0] | 0x5a00; | |
115 | break; | |
116 | case 2: | |
117 | mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; | |
118 | break; | |
119 | case 3: | |
120 | mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | | |
121 | 0x5a000000; | |
122 | break; | |
123 | } | |
124 | michael_block(mctx->l, mctx->r); | |
125 | /* l ^= 0; */ | |
126 | michael_block(mctx->l, mctx->r); | |
127 | ||
128 | put_le32(out, mctx->l); | |
129 | put_le32(out + 4, mctx->r); | |
130 | } | |
131 | ||
132 | ||
133 | static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen, | |
134 | u32 *flags) | |
135 | { | |
136 | struct michael_mic_ctx *mctx = ctx; | |
137 | if (keylen != 8) { | |
138 | if (flags) | |
139 | *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; | |
140 | return -EINVAL; | |
141 | } | |
142 | mctx->l = get_le32(key); | |
143 | mctx->r = get_le32(key + 4); | |
144 | return 0; | |
145 | } | |
146 | ||
147 | ||
148 | static struct crypto_alg michael_mic_alg = { | |
149 | .cra_name = "michael_mic", | |
150 | .cra_flags = CRYPTO_ALG_TYPE_DIGEST, | |
151 | .cra_blocksize = 8, | |
152 | .cra_ctxsize = sizeof(struct michael_mic_ctx), | |
153 | .cra_module = THIS_MODULE, | |
154 | .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list), | |
155 | .cra_u = { .digest = { | |
156 | .dia_digestsize = 8, | |
157 | .dia_init = michael_init, | |
158 | .dia_update = michael_update, | |
159 | .dia_final = michael_final, | |
160 | .dia_setkey = michael_setkey } } | |
161 | }; | |
162 | ||
163 | ||
164 | static int __init michael_mic_init(void) | |
165 | { | |
166 | return crypto_register_alg(&michael_mic_alg); | |
167 | } | |
168 | ||
169 | ||
170 | static void __exit michael_mic_exit(void) | |
171 | { | |
172 | crypto_unregister_alg(&michael_mic_alg); | |
173 | } | |
174 | ||
175 | ||
176 | module_init(michael_mic_init); | |
177 | module_exit(michael_mic_exit); | |
178 | ||
179 | MODULE_LICENSE("GPL v2"); | |
180 | MODULE_DESCRIPTION("Michael MIC"); | |
181 | MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>"); |