/*
   * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
   * Copyright 2008, Jouni Malinen <j@w1.fi>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/crypto.h>
  #include <linux/err.h>

  #include <crypto/aes.h>

  
  #include <net/mac80211.h>
  #include "key.h"
  #include "aes_cmac.h"

  #define AES_CMAC_KEY_LEN 16
  #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
  #define AAD_LEN 20
  
  
  static void gf_mulx(u8 *pad)
  {
  	int i, carry;
  
  	carry = pad[0] & 0x80;
  	for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
  		pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
  	pad[AES_BLOCK_SIZE - 1] <<= 1;
  	if (carry)
  		pad[AES_BLOCK_SIZE - 1] ^= 0x87;
  }

  static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,

  				const u8 *addr[], const size_t *len, u8 *mac)
  {

  	u8 scratch[2 * AES_BLOCK_SIZE];

  	u8 *cbc, *pad;
  	const u8 *pos, *end;
  	size_t i, e, left, total_len;
  
  	cbc = scratch;
  	pad = scratch + AES_BLOCK_SIZE;
  
  	memset(cbc, 0, AES_BLOCK_SIZE);
  
  	total_len = 0;
  	for (e = 0; e < num_elem; e++)
  		total_len += len[e];
  	left = total_len;
  
  	e = 0;
  	pos = addr[0];
  	end = pos + len[0];
  
  	while (left >= AES_BLOCK_SIZE) {
  		for (i = 0; i < AES_BLOCK_SIZE; i++) {
  			cbc[i] ^= *pos++;
  			if (pos >= end) {
  				e++;
  				pos = addr[e];
  				end = pos + len[e];
  			}
  		}
  		if (left > AES_BLOCK_SIZE)
  			crypto_cipher_encrypt_one(tfm, cbc, cbc);
  		left -= AES_BLOCK_SIZE;
  	}
  
  	memset(pad, 0, AES_BLOCK_SIZE);
  	crypto_cipher_encrypt_one(tfm, pad, pad);
  	gf_mulx(pad);
  
  	if (left || total_len == 0) {
  		for (i = 0; i < left; i++) {
  			cbc[i] ^= *pos++;
  			if (pos >= end) {
  				e++;
  				pos = addr[e];
  				end = pos + len[e];
  			}
  		}
  		cbc[left] ^= 0x80;
  		gf_mulx(pad);
  	}
  
  	for (i = 0; i < AES_BLOCK_SIZE; i++)
  		pad[i] ^= cbc[i];
  	crypto_cipher_encrypt_one(tfm, pad, pad);
  	memcpy(mac, pad, CMAC_TLEN);
  }

  void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,

  			const u8 *data, size_t data_len, u8 *mic)
  {
  	const u8 *addr[3];
  	size_t len[3];
  	u8 zero[CMAC_TLEN];
  
  	memset(zero, 0, CMAC_TLEN);
  	addr[0] = aad;
  	len[0] = AAD_LEN;
  	addr[1] = data;
  	len[1] = data_len - CMAC_TLEN;
  	addr[2] = zero;
  	len[2] = CMAC_TLEN;

  	aes_128_cmac_vector(tfm, 3, addr, len, mic);

  }
  
  
  struct crypto_cipher * ieee80211_aes_cmac_key_setup(const u8 key[])
  {
  	struct crypto_cipher *tfm;
  
  	tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);

  	if (!IS_ERR(tfm))
  		crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);

  
  	return tfm;
  }
  
  
  void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
  {

  	crypto_free_cipher(tfm);

  }