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 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 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 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 68 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm) 69 { 70 crypto_free_shash(tfm); 71 } 72