e55569bee7d081c6a827883cbd900784a7e27066
[openwrt/openwrt.git] / package / mac80211 / src / mac80211 / aes_ccm.c
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/types.h>
11 #include <linux/crypto.h>
12 #include <linux/err.h>
13 #include <asm/scatterlist.h>
14
15 #include <net/mac80211.h>
16 #include "ieee80211_key.h"
17 #include "aes_ccm.h"
18
19
20 static void ieee80211_aes_encrypt(struct crypto_cipher *tfm,
21 const u8 pt[16], u8 ct[16])
22 {
23 crypto_cipher_encrypt_one(tfm, ct, pt);
24 }
25
26
27 static inline void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *b_0, u8 *aad,
28 u8 *b, u8 *s_0, u8 *a)
29 {
30 int i;
31
32 ieee80211_aes_encrypt(tfm, b_0, b);
33
34 /* Extra Authenticate-only data (always two AES blocks) */
35 for (i = 0; i < AES_BLOCK_LEN; i++)
36 aad[i] ^= b[i];
37 ieee80211_aes_encrypt(tfm, aad, b);
38
39 aad += AES_BLOCK_LEN;
40
41 for (i = 0; i < AES_BLOCK_LEN; i++)
42 aad[i] ^= b[i];
43 ieee80211_aes_encrypt(tfm, aad, a);
44
45 /* Mask out bits from auth-only-b_0 */
46 b_0[0] &= 0x07;
47
48 /* S_0 is used to encrypt T (= MIC) */
49 b_0[14] = 0;
50 b_0[15] = 0;
51 ieee80211_aes_encrypt(tfm, b_0, s_0);
52 }
53
54
55 void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch,
56 u8 *b_0, u8 *aad, u8 *data, size_t data_len,
57 u8 *cdata, u8 *mic)
58 {
59 int i, j, last_len, num_blocks;
60 u8 *pos, *cpos, *b, *s_0, *e;
61
62 b = scratch;
63 s_0 = scratch + AES_BLOCK_LEN;
64 e = scratch + 2 * AES_BLOCK_LEN;
65
66 num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
67 last_len = data_len % AES_BLOCK_LEN;
68 aes_ccm_prepare(tfm, b_0, aad, b, s_0, b);
69
70 /* Process payload blocks */
71 pos = data;
72 cpos = cdata;
73 for (j = 1; j <= num_blocks; j++) {
74 int blen = (j == num_blocks && last_len) ?
75 last_len : AES_BLOCK_LEN;
76
77 /* Authentication followed by encryption */
78 for (i = 0; i < blen; i++)
79 b[i] ^= pos[i];
80 ieee80211_aes_encrypt(tfm, b, b);
81
82 b_0[14] = (j >> 8) & 0xff;
83 b_0[15] = j & 0xff;
84 ieee80211_aes_encrypt(tfm, b_0, e);
85 for (i = 0; i < blen; i++)
86 *cpos++ = *pos++ ^ e[i];
87 }
88
89 for (i = 0; i < CCMP_MIC_LEN; i++)
90 mic[i] = b[i] ^ s_0[i];
91 }
92
93
94 int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch,
95 u8 *b_0, u8 *aad, u8 *cdata, size_t data_len,
96 u8 *mic, u8 *data)
97 {
98 int i, j, last_len, num_blocks;
99 u8 *pos, *cpos, *b, *s_0, *a;
100
101 b = scratch;
102 s_0 = scratch + AES_BLOCK_LEN;
103 a = scratch + 2 * AES_BLOCK_LEN;
104
105 num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
106 last_len = data_len % AES_BLOCK_LEN;
107 aes_ccm_prepare(tfm, b_0, aad, b, s_0, 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 ieee80211_aes_encrypt(tfm, b_0, b);
120 for (i = 0; i < blen; i++) {
121 *pos = *cpos++ ^ b[i];
122 a[i] ^= *pos++;
123 }
124
125 ieee80211_aes_encrypt(tfm, a, a);
126 }
127
128 for (i = 0; i < CCMP_MIC_LEN; i++) {
129 if ((mic[i] ^ s_0[i]) != a[i])
130 return -1;
131 }
132
133 return 0;
134 }
135
136
137 struct crypto_cipher * ieee80211_aes_key_setup_encrypt(const u8 key[])
138 {
139 struct crypto_cipher *tfm;
140
141 tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
142 if (IS_ERR(tfm))
143 return NULL;
144
145 crypto_cipher_setkey(tfm, key, ALG_CCMP_KEY_LEN);
146
147 return tfm;
148 }
149
150
151 void ieee80211_aes_key_free(struct crypto_cipher *tfm)
152 {
153 if (tfm)
154 crypto_free_cipher(tfm);
155 }