1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/*
* Copyright 2003-2004, Instant802 Networks, Inc.
* Copyright 2005-2006, Devicescape Software, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/err.h>
#include <net/mac80211.h>
#include "key.h"
#include "aes_ccm.h"
static void ieee80211_aes_encrypt(struct crypto_cipher *tfm,
const u8 pt[16], u8 ct[16])
{
crypto_cipher_encrypt_one(tfm, ct, pt);
}
static inline void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *b_0, u8 *aad,
u8 *b, u8 *s_0, u8 *a)
{
int i;
ieee80211_aes_encrypt(tfm, b_0, b);
/* Extra Authenticate-only data (always two AES blocks) */
for (i = 0; i < AES_BLOCK_LEN; i++)
aad[i] ^= b[i];
ieee80211_aes_encrypt(tfm, aad, b);
aad += AES_BLOCK_LEN;
for (i = 0; i < AES_BLOCK_LEN; i++)
aad[i] ^= b[i];
ieee80211_aes_encrypt(tfm, aad, a);
/* Mask out bits from auth-only-b_0 */
b_0[0] &= 0x07;
/* S_0 is used to encrypt T (= MIC) */
b_0[14] = 0;
b_0[15] = 0;
ieee80211_aes_encrypt(tfm, b_0, s_0);
}
void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch,
u8 *data, size_t data_len,
u8 *cdata, u8 *mic)
{
int i, j, last_len, num_blocks;
u8 *pos, *cpos, *b, *s_0, *e, *b_0, *aad;
b = scratch;
s_0 = scratch + AES_BLOCK_LEN;
e = scratch + 2 * AES_BLOCK_LEN;
b_0 = scratch + 3 * AES_BLOCK_LEN;
aad = scratch + 4 * AES_BLOCK_LEN;
num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
last_len = data_len % AES_BLOCK_LEN;
aes_ccm_prepare(tfm, b_0, aad, b, s_0, b);
/* Process payload blocks */
pos = data;
cpos = cdata;
for (j = 1; j <= num_blocks; j++) {
int blen = (j == num_blocks && last_len) ?
last_len : AES_BLOCK_LEN;
/* Authentication followed by encryption */
for (i = 0; i < blen; i++)
b[i] ^= pos[i];
ieee80211_aes_encrypt(tfm, b, b);
b_0[14] = (j >> 8) & 0xff;
b_0[15] = j & 0xff;
ieee80211_aes_encrypt(tfm, b_0, e);
for (i = 0; i < blen; i++)
*cpos++ = *pos++ ^ e[i];
}
for (i = 0; i < CCMP_MIC_LEN; i++)
mic[i] = b[i] ^ s_0[i];
}
int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch,
u8 *cdata, size_t data_len, u8 *mic, u8 *data)
{
int i, j, last_len, num_blocks;
u8 *pos, *cpos, *b, *s_0, *a, *b_0, *aad;
b = scratch;
s_0 = scratch + AES_BLOCK_LEN;
a = scratch + 2 * AES_BLOCK_LEN;
b_0 = scratch + 3 * AES_BLOCK_LEN;
aad = scratch + 4 * AES_BLOCK_LEN;
num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
last_len = data_len % AES_BLOCK_LEN;
aes_ccm_prepare(tfm, b_0, aad, b, s_0, a);
/* Process payload blocks */
cpos = cdata;
pos = data;
for (j = 1; j <= num_blocks; j++) {
int blen = (j == num_blocks && last_len) ?
last_len : AES_BLOCK_LEN;
/* Decryption followed by authentication */
b_0[14] = (j >> 8) & 0xff;
b_0[15] = j & 0xff;
ieee80211_aes_encrypt(tfm, b_0, b);
for (i = 0; i < blen; i++) {
*pos = *cpos++ ^ b[i];
a[i] ^= *pos++;
}
ieee80211_aes_encrypt(tfm, a, a);
}
for (i = 0; i < CCMP_MIC_LEN; i++) {
if ((mic[i] ^ s_0[i]) != a[i])
return -1;
}
return 0;
}
struct crypto_cipher *ieee80211_aes_key_setup_encrypt(const u8 key[])
{
struct crypto_cipher *tfm;
tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
return NULL;
crypto_cipher_setkey(tfm, key, ALG_CCMP_KEY_LEN);
return tfm;
}
void ieee80211_aes_key_free(struct crypto_cipher *tfm)
{
if (tfm)
crypto_free_cipher(tfm);
}
|
