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 CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
22 #define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
23 #define AAD_LEN 20
24
25 static const u8 zero[CMAC_TLEN_256];
26
ieee80211_aes_cmac(struct crypto_shash * tfm,const u8 * aad,const u8 * data,size_t data_len,u8 * mic)27 void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
28 const u8 *data, size_t data_len, u8 *mic)
29 {
30 SHASH_DESC_ON_STACK(desc, tfm);
31 u8 out[AES_BLOCK_SIZE];
32
33 desc->tfm = tfm;
34
35 crypto_shash_init(desc);
36 crypto_shash_update(desc, aad, AAD_LEN);
37 crypto_shash_update(desc, data, data_len - CMAC_TLEN);
38 crypto_shash_finup(desc, zero, CMAC_TLEN, out);
39
40 memcpy(mic, out, CMAC_TLEN);
41 }
42
ieee80211_aes_cmac_256(struct crypto_shash * tfm,const u8 * aad,const u8 * data,size_t data_len,u8 * mic)43 void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
44 const u8 *data, size_t data_len, u8 *mic)
45 {
46 SHASH_DESC_ON_STACK(desc, tfm);
47
48 desc->tfm = tfm;
49
50 crypto_shash_init(desc);
51 crypto_shash_update(desc, aad, AAD_LEN);
52 crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
53 crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
54 }
55
ieee80211_aes_cmac_key_setup(const u8 key[],size_t key_len)56 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
57 size_t key_len)
58 {
59 struct crypto_shash *tfm;
60
61 tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
62 if (!IS_ERR(tfm))
63 crypto_shash_setkey(tfm, key, key_len);
64
65 return tfm;
66 }
67
ieee80211_aes_cmac_key_free(struct crypto_shash * tfm)68 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
69 {
70 crypto_free_shash(tfm);
71 }
72
