net/mac80211/aes_cmac.c

   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 }