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Jouni Malinen765cb462009-01-08 13:32:01 +02001/*
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>
Emmanuel Grumbach4afebd62012-11-07 11:13:58 +020013#include <linux/export.h>
Jouni Malinen765cb462009-01-08 13:32:01 +020014#include <linux/err.h>
Johannes Berg0cd20a22011-07-06 22:02:14 +020015#include <crypto/aes.h>
Jouni Malinen765cb462009-01-08 13:32:01 +020016
17#include <net/mac80211.h>
18#include "key.h"
19#include "aes_cmac.h"
20
Jouni Malinen765cb462009-01-08 13:32:01 +020021#define AES_CMAC_KEY_LEN 16
22#define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
23#define AAD_LEN 20
24
25
26static 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
Johannes Berg75396ae2011-07-06 22:00:35 +020039static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,
Jouni Malinen765cb462009-01-08 13:32:01 +020040 const u8 *addr[], const size_t *len, u8 *mac)
41{
Johannes Bergd348f692012-08-19 14:51:44 +020042 u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
Jouni Malinen765cb462009-01-08 13:32:01 +020043 const u8 *pos, *end;
44 size_t i, e, left, total_len;
45
Jouni Malinen765cb462009-01-08 13:32:01 +020046 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
Johannes Berg75396ae2011-07-06 22:00:35 +020095void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
Jouni Malinen765cb462009-01-08 13:32:01 +020096 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
Johannes Berg75396ae2011-07-06 22:00:35 +0200110 aes_128_cmac_vector(tfm, 3, addr, len, mic);
Jouni Malinen765cb462009-01-08 13:32:01 +0200111}
112
113
114struct 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);
Ben Hutchings1ac62ba2010-08-01 17:37:03 +0100119 if (!IS_ERR(tfm))
120 crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);
Jouni Malinen765cb462009-01-08 13:32:01 +0200121
122 return tfm;
123}
124
125
126void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
127{
Jesper Juhlffa56e542010-11-04 22:59:56 +0100128 crypto_free_cipher(tfm);
Jouni Malinen765cb462009-01-08 13:32:01 +0200129}
Assaf Krauss5d0d04e2012-08-01 15:12:48 +0300130
131void 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}
146EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2);