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1 | /* |
2 | * Copyright 2003-2004, Instant802 Networks, Inc. |
3 | * Copyright 2005-2006, Devicescape Software, Inc. |
4 | * |
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. |
8 | */ |
9 | |
10 | #include <linux/kernel.h> |
11 | #include <linux/types.h> |
12 | #include <linux/crypto.h> |
13 | #include <linux/err.h> |
14 | |
15 | #include <net/mac80211.h> |
16 | #include "key.h" |
17 | #include "aes_ccm.h" |
18 | |
19 | static void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *scratch, u8 *a) |
20 | { |
21 | int i; |
22 | u8 *b_0, *aad, *b, *s_0; |
23 | |
24 | b_0 = scratch + 3 * AES_BLOCK_LEN; |
25 | aad = scratch + 4 * AES_BLOCK_LEN; |
26 | b = scratch; |
27 | s_0 = scratch + AES_BLOCK_LEN; |
28 | |
29 | crypto_cipher_encrypt_one(tfm, b, b_0); |
30 | |
31 | /* Extra Authenticate-only data (always two AES blocks) */ |
32 | for (i = 0; i < AES_BLOCK_LEN; i++) |
33 | aad[i] ^= b[i]; |
34 | crypto_cipher_encrypt_one(tfm, b, aad); |
35 | |
36 | aad += AES_BLOCK_LEN; |
37 | |
38 | for (i = 0; i < AES_BLOCK_LEN; i++) |
39 | aad[i] ^= b[i]; |
40 | crypto_cipher_encrypt_one(tfm, a, aad); |
41 | |
42 | /* Mask out bits from auth-only-b_0 */ |
43 | b_0[0] &= 0x07; |
44 | |
45 | /* S_0 is used to encrypt T (= MIC) */ |
46 | b_0[14] = 0; |
47 | b_0[15] = 0; |
48 | crypto_cipher_encrypt_one(tfm, s_0, b_0); |
49 | } |
50 | |
51 | |
52 | void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch, |
53 | u8 *data, size_t data_len, |
54 | u8 *cdata, u8 *mic) |
55 | { |
56 | int i, j, last_len, num_blocks; |
57 | u8 *pos, *cpos, *b, *s_0, *e, *b_0, *aad; |
58 | |
59 | b = scratch; |
60 | s_0 = scratch + AES_BLOCK_LEN; |
61 | e = scratch + 2 * AES_BLOCK_LEN; |
62 | b_0 = scratch + 3 * AES_BLOCK_LEN; |
63 | aad = scratch + 4 * AES_BLOCK_LEN; |
64 | |
65 | num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); |
66 | last_len = data_len % AES_BLOCK_LEN; |
67 | aes_ccm_prepare(tfm, scratch, b); |
68 | |
69 | /* Process payload blocks */ |
70 | pos = data; |
71 | cpos = cdata; |
72 | for (j = 1; j <= num_blocks; j++) { |
73 | int blen = (j == num_blocks && last_len) ? |
74 | last_len : AES_BLOCK_LEN; |
75 | |
76 | /* Authentication followed by encryption */ |
77 | for (i = 0; i < blen; i++) |
78 | b[i] ^= pos[i]; |
79 | crypto_cipher_encrypt_one(tfm, b, b); |
80 | |
81 | b_0[14] = (j >> 8) & 0xff; |
82 | b_0[15] = j & 0xff; |
83 | crypto_cipher_encrypt_one(tfm, e, b_0); |
84 | for (i = 0; i < blen; i++) |
85 | *cpos++ = *pos++ ^ e[i]; |
86 | } |
87 | |
88 | for (i = 0; i < CCMP_MIC_LEN; i++) |
89 | mic[i] = b[i] ^ s_0[i]; |
90 | } |
91 | |
92 | |
93 | int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch, |
94 | u8 *cdata, size_t data_len, u8 *mic, u8 *data) |
95 | { |
96 | int i, j, last_len, num_blocks; |
97 | u8 *pos, *cpos, *b, *s_0, *a, *b_0, *aad; |
98 | |
99 | b = scratch; |
100 | s_0 = scratch + AES_BLOCK_LEN; |
101 | a = scratch + 2 * AES_BLOCK_LEN; |
102 | b_0 = scratch + 3 * AES_BLOCK_LEN; |
103 | aad = scratch + 4 * AES_BLOCK_LEN; |
104 | |
105 | num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); |
106 | last_len = data_len % AES_BLOCK_LEN; |
107 | aes_ccm_prepare(tfm, scratch, a); |
108 | |
109 | /* Process payload blocks */ |
110 | cpos = cdata; |
111 | pos = data; |
112 | for (j = 1; j <= num_blocks; j++) { |
113 | int blen = (j == num_blocks && last_len) ? |
114 | last_len : AES_BLOCK_LEN; |
115 | |
116 | /* Decryption followed by authentication */ |
117 | b_0[14] = (j >> 8) & 0xff; |
118 | b_0[15] = j & 0xff; |
119 | crypto_cipher_encrypt_one(tfm, b, b_0); |
120 | for (i = 0; i < blen; i++) { |
121 | *pos = *cpos++ ^ b[i]; |
122 | a[i] ^= *pos++; |
123 | } |
124 | crypto_cipher_encrypt_one(tfm, a, a); |
125 | } |
126 | |
127 | for (i = 0; i < CCMP_MIC_LEN; i++) { |
128 | if ((mic[i] ^ s_0[i]) != a[i]) |
129 | return -1; |
130 | } |
131 | |
132 | return 0; |
133 | } |
134 | |
135 | |
136 | struct crypto_cipher *ieee80211_aes_key_setup_encrypt(const u8 key[]) |
137 | { |
138 | struct crypto_cipher *tfm; |
139 | |
140 | tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); |
141 | if (IS_ERR(tfm)) |
142 | return NULL; |
143 | |
144 | crypto_cipher_setkey(tfm, key, ALG_CCMP_KEY_LEN); |
145 | |
146 | return tfm; |
147 | } |
148 | |
149 | |
150 | void ieee80211_aes_key_free(struct crypto_cipher *tfm) |
151 | { |
152 | if (tfm) |
153 | crypto_free_cipher(tfm); |
154 | } |
155 |
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