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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/export.h> |
14 | #include <linux/err.h> |
15 | #include <crypto/aes.h> |
16 | |
17 | #include <net/mac80211.h> |
18 | #include "key.h" |
19 | #include "aes_cmac.h" |
20 | |
21 | #define AES_CMAC_KEY_LEN 16 |
22 | #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */ |
23 | #define AAD_LEN 20 |
24 | |
25 | |
26 | static void gf_mulx(u8 *pad) |
27 | { |
28 | int i, carry; |
29 | |
30 | carry = pad[0] & 0x80; |
31 | for (i = 0; i < AES_BLOCK_SIZE - 1; i++) |
32 | pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7); |
33 | pad[AES_BLOCK_SIZE - 1] <<= 1; |
34 | if (carry) |
35 | pad[AES_BLOCK_SIZE - 1] ^= 0x87; |
36 | } |
37 | |
38 | |
39 | static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem, |
40 | const u8 *addr[], const size_t *len, u8 *mac) |
41 | { |
42 | u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE]; |
43 | const u8 *pos, *end; |
44 | size_t i, e, left, total_len; |
45 | |
46 | memset(cbc, 0, AES_BLOCK_SIZE); |
47 | |
48 | total_len = 0; |
49 | for (e = 0; e < num_elem; e++) |
50 | total_len += len[e]; |
51 | left = total_len; |
52 | |
53 | e = 0; |
54 | pos = addr[0]; |
55 | end = pos + len[0]; |
56 | |
57 | while (left >= AES_BLOCK_SIZE) { |
58 | for (i = 0; i < AES_BLOCK_SIZE; i++) { |
59 | cbc[i] ^= *pos++; |
60 | if (pos >= end) { |
61 | e++; |
62 | pos = addr[e]; |
63 | end = pos + len[e]; |
64 | } |
65 | } |
66 | if (left > AES_BLOCK_SIZE) |
67 | crypto_cipher_encrypt_one(tfm, cbc, cbc); |
68 | left -= AES_BLOCK_SIZE; |
69 | } |
70 | |
71 | memset(pad, 0, AES_BLOCK_SIZE); |
72 | crypto_cipher_encrypt_one(tfm, pad, pad); |
73 | gf_mulx(pad); |
74 | |
75 | if (left || total_len == 0) { |
76 | for (i = 0; i < left; i++) { |
77 | cbc[i] ^= *pos++; |
78 | if (pos >= end) { |
79 | e++; |
80 | pos = addr[e]; |
81 | end = pos + len[e]; |
82 | } |
83 | } |
84 | cbc[left] ^= 0x80; |
85 | gf_mulx(pad); |
86 | } |
87 | |
88 | for (i = 0; i < AES_BLOCK_SIZE; i++) |
89 | pad[i] ^= cbc[i]; |
90 | crypto_cipher_encrypt_one(tfm, pad, pad); |
91 | memcpy(mac, pad, CMAC_TLEN); |
92 | } |
93 | |
94 | |
95 | void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad, |
96 | const u8 *data, size_t data_len, u8 *mic) |
97 | { |
98 | const u8 *addr[3]; |
99 | size_t len[3]; |
100 | u8 zero[CMAC_TLEN]; |
101 | |
102 | memset(zero, 0, CMAC_TLEN); |
103 | addr[0] = aad; |
104 | len[0] = AAD_LEN; |
105 | addr[1] = data; |
106 | len[1] = data_len - CMAC_TLEN; |
107 | addr[2] = zero; |
108 | len[2] = CMAC_TLEN; |
109 | |
110 | aes_128_cmac_vector(tfm, 3, addr, len, mic); |
111 | } |
112 | |
113 | |
114 | struct crypto_cipher *ieee80211_aes_cmac_key_setup(const u8 key[]) |
115 | { |
116 | struct crypto_cipher *tfm; |
117 | |
118 | tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); |
119 | if (!IS_ERR(tfm)) |
120 | crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN); |
121 | |
122 | return tfm; |
123 | } |
124 | |
125 | |
126 | void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm) |
127 | { |
128 | crypto_free_cipher(tfm); |
129 | } |
130 | |
131 | void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf, |
132 | u8 *k1, u8 *k2) |
133 | { |
134 | u8 l[AES_BLOCK_SIZE] = {}; |
135 | struct ieee80211_key *key = |
136 | container_of(keyconf, struct ieee80211_key, conf); |
137 | |
138 | crypto_cipher_encrypt_one(key->u.aes_cmac.tfm, l, l); |
139 | |
140 | memcpy(k1, l, AES_BLOCK_SIZE); |
141 | gf_mulx(k1); |
142 | |
143 | memcpy(k2, k1, AES_BLOCK_SIZE); |
144 | gf_mulx(k2); |
145 | } |
146 | EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2); |
147 |
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