tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
14#include <crypto/aes.h>
15
16#include <net/mac80211.h>
17#include "key.h"
18#include "aes_cmac.h"
19
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
25static 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
38static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,
39 const u8 *addr[], const size_t *len, u8 *mac)
40{
41 u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
42 const u8 *pos, *end;
43 size_t i, e, left, total_len;
44
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
94void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
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
109 aes_128_cmac_vector(tfm, 3, addr, len, mic);
110}
111
112
113struct 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);
118 if (!IS_ERR(tfm))
119 crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);
120
121 return tfm;
122}
123
124
125void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
126{
127 crypto_free_cipher(tfm);
128}