]>
Commit | Line | Data |
---|---|---|
765cb46a JM |
1 | /* |
2 | * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP | |
3 | * Copyright 2008, Jouni Malinen <j@w1.fi> | |
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> | |
0cd20a27 | 14 | #include <crypto/aes.h> |
765cb46a JM |
15 | |
16 | #include <net/mac80211.h> | |
17 | #include "key.h" | |
18 | #include "aes_cmac.h" | |
19 | ||
765cb46a JM |
20 | #define AES_CMAC_KEY_LEN 16 |
21 | #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */ | |
22 | #define AAD_LEN 20 | |
23 | ||
24 | ||
25 | static void gf_mulx(u8 *pad) | |
26 | { | |
27 | int i, carry; | |
28 | ||
29 | carry = pad[0] & 0x80; | |
30 | for (i = 0; i < AES_BLOCK_SIZE - 1; i++) | |
31 | pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7); | |
32 | pad[AES_BLOCK_SIZE - 1] <<= 1; | |
33 | if (carry) | |
34 | pad[AES_BLOCK_SIZE - 1] ^= 0x87; | |
35 | } | |
36 | ||
37 | ||
75396ae6 | 38 | static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem, |
765cb46a JM |
39 | const u8 *addr[], const size_t *len, u8 *mac) |
40 | { | |
d348f69f | 41 | u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE]; |
765cb46a JM |
42 | const u8 *pos, *end; |
43 | size_t i, e, left, total_len; | |
44 | ||
765cb46a JM |
45 | memset(cbc, 0, AES_BLOCK_SIZE); |
46 | ||
47 | total_len = 0; | |
48 | for (e = 0; e < num_elem; e++) | |
49 | total_len += len[e]; | |
50 | left = total_len; | |
51 | ||
52 | e = 0; | |
53 | pos = addr[0]; | |
54 | end = pos + len[0]; | |
55 | ||
56 | while (left >= AES_BLOCK_SIZE) { | |
57 | for (i = 0; i < AES_BLOCK_SIZE; i++) { | |
58 | cbc[i] ^= *pos++; | |
59 | if (pos >= end) { | |
60 | e++; | |
61 | pos = addr[e]; | |
62 | end = pos + len[e]; | |
63 | } | |
64 | } | |
65 | if (left > AES_BLOCK_SIZE) | |
66 | crypto_cipher_encrypt_one(tfm, cbc, cbc); | |
67 | left -= AES_BLOCK_SIZE; | |
68 | } | |
69 | ||
70 | memset(pad, 0, AES_BLOCK_SIZE); | |
71 | crypto_cipher_encrypt_one(tfm, pad, pad); | |
72 | gf_mulx(pad); | |
73 | ||
74 | if (left || total_len == 0) { | |
75 | for (i = 0; i < left; i++) { | |
76 | cbc[i] ^= *pos++; | |
77 | if (pos >= end) { | |
78 | e++; | |
79 | pos = addr[e]; | |
80 | end = pos + len[e]; | |
81 | } | |
82 | } | |
83 | cbc[left] ^= 0x80; | |
84 | gf_mulx(pad); | |
85 | } | |
86 | ||
87 | for (i = 0; i < AES_BLOCK_SIZE; i++) | |
88 | pad[i] ^= cbc[i]; | |
89 | crypto_cipher_encrypt_one(tfm, pad, pad); | |
90 | memcpy(mac, pad, CMAC_TLEN); | |
91 | } | |
92 | ||
93 | ||
75396ae6 | 94 | void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad, |
765cb46a JM |
95 | const u8 *data, size_t data_len, u8 *mic) |
96 | { | |
97 | const u8 *addr[3]; | |
98 | size_t len[3]; | |
99 | u8 zero[CMAC_TLEN]; | |
100 | ||
101 | memset(zero, 0, CMAC_TLEN); | |
102 | addr[0] = aad; | |
103 | len[0] = AAD_LEN; | |
104 | addr[1] = data; | |
105 | len[1] = data_len - CMAC_TLEN; | |
106 | addr[2] = zero; | |
107 | len[2] = CMAC_TLEN; | |
108 | ||
75396ae6 | 109 | aes_128_cmac_vector(tfm, 3, addr, len, mic); |
765cb46a JM |
110 | } |
111 | ||
112 | ||
113 | struct crypto_cipher * ieee80211_aes_cmac_key_setup(const u8 key[]) | |
114 | { | |
115 | struct crypto_cipher *tfm; | |
116 | ||
117 | tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); | |
1ac62ba7 BH |
118 | if (!IS_ERR(tfm)) |
119 | crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN); | |
765cb46a JM |
120 | |
121 | return tfm; | |
122 | } | |
123 | ||
124 | ||
125 | void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm) | |
126 | { | |
ffa56e54 | 127 | crypto_free_cipher(tfm); |
765cb46a | 128 | } |