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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> | |
4afebd63 | 13 | #include <linux/export.h> |
765cb46a | 14 | #include <linux/err.h> |
0cd20a27 | 15 | #include <crypto/aes.h> |
765cb46a JM |
16 | |
17 | #include <net/mac80211.h> | |
18 | #include "key.h" | |
19 | #include "aes_cmac.h" | |
20 | ||
765cb46a JM |
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 | ||
75396ae6 | 39 | static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem, |
765cb46a JM |
40 | const u8 *addr[], const size_t *len, u8 *mac) |
41 | { | |
d348f69f | 42 | u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE]; |
765cb46a JM |
43 | const u8 *pos, *end; |
44 | size_t i, e, left, total_len; | |
45 | ||
765cb46a JM |
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 | ||
75396ae6 | 95 | void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad, |
765cb46a JM |
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 | ||
75396ae6 | 110 | aes_128_cmac_vector(tfm, 3, addr, len, mic); |
765cb46a JM |
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); | |
1ac62ba7 BH |
119 | if (!IS_ERR(tfm)) |
120 | crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN); | |
765cb46a JM |
121 | |
122 | return tfm; | |
123 | } | |
124 | ||
125 | ||
126 | void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm) | |
127 | { | |
ffa56e54 | 128 | crypto_free_cipher(tfm); |
765cb46a | 129 | } |
5d0d04e4 AK |
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); |