Line data    Source code

       1             : /*
       2             :  * AES-128 CTR
       3             :  *
       4             :  * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
       5             :  *
       6             :  * This software may be distributed under the terms of the BSD license.
       7             :  * See README for more details.
       8             :  */
       9             : 
      10             : #include "includes.h"
      11             : 
      12             : #include "common.h"
      13             : #include "aes.h"
      14             : #include "aes_wrap.h"
      15             : 
      16             : /**
      17             :  * aes_128_ctr_encrypt - AES-128 CTR mode encryption
      18             :  * @key: Key for encryption (16 bytes)
      19             :  * @nonce: Nonce for counter mode (16 bytes)
      20             :  * @data: Data to encrypt in-place
      21             :  * @data_len: Length of data in bytes
      22             :  * Returns: 0 on success, -1 on failure
      23             :  */
      24          68 : int aes_128_ctr_encrypt(const u8 *key, const u8 *nonce,
      25             :                         u8 *data, size_t data_len)
      26             : {
      27             :         void *ctx;
      28          68 :         size_t j, len, left = data_len;
      29             :         int i;
      30          68 :         u8 *pos = data;
      31             :         u8 counter[AES_BLOCK_SIZE], buf[AES_BLOCK_SIZE];
      32             : 
      33          68 :         ctx = aes_encrypt_init(key, 16);
      34          68 :         if (ctx == NULL)
      35           0 :                 return -1;
      36          68 :         os_memcpy(counter, nonce, AES_BLOCK_SIZE);
      37             : 
      38         204 :         while (left > 0) {
      39          68 :                 aes_encrypt(ctx, counter, buf);
      40             : 
      41          68 :                 len = (left < AES_BLOCK_SIZE) ? left : AES_BLOCK_SIZE;
      42         136 :                 for (j = 0; j < len; j++)
      43          68 :                         pos[j] ^= buf[j];
      44          68 :                 pos += len;
      45          68 :                 left -= len;
      46             : 
      47          68 :                 for (i = AES_BLOCK_SIZE - 1; i >= 0; i--) {
      48          68 :                         counter[i]++;
      49          68 :                         if (counter[i])
      50          68 :                                 break;
      51             :                 }
      52             :         }
      53          68 :         aes_encrypt_deinit(ctx);
      54          68 :         return 0;
      55             : }