src/crypto/aes-cbc.c

   1 /*
   2  * AES-128 CBC
   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_cbc_encrypt - AES-128 CBC encryption
  18  * @key: Encryption key
  19  * @iv: Encryption IV for CBC mode (16 bytes)
  20  * @data: Data to encrypt in-place
  21  * @data_len: Length of data in bytes (must be divisible by 16)
  22  * Returns: 0 on success, -1 on failure
  23  */
  24 int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
  25 {
  26         void *ctx;
  27         u8 cbc[AES_BLOCK_SIZE];
  28         u8 *pos = data;
  29         int i, j, blocks;
  30
  31         if (TEST_FAIL())
  32                 return -1;
  33
  34         ctx = aes_encrypt_init(key, 16);
  35         if (ctx == NULL)
  36                 return -1;
  37         os_memcpy(cbc, iv, AES_BLOCK_SIZE);
  38
  39         blocks = data_len / AES_BLOCK_SIZE;
  40         for (i = 0; i < blocks; i++) {
  41                 for (j = 0; j < AES_BLOCK_SIZE; j++)
  42                         cbc[j] ^= pos[j];
  43                 aes_encrypt(ctx, cbc, cbc);
  44                 os_memcpy(pos, cbc, AES_BLOCK_SIZE);
  45                 pos += AES_BLOCK_SIZE;
  46         }
  47         aes_encrypt_deinit(ctx);
  48         return 0;
  49 }
  50
  51
  52 /**
  53  * aes_128_cbc_decrypt - AES-128 CBC decryption
  54  * @key: Decryption key
  55  * @iv: Decryption IV for CBC mode (16 bytes)
  56  * @data: Data to decrypt in-place
  57  * @data_len: Length of data in bytes (must be divisible by 16)
  58  * Returns: 0 on success, -1 on failure
  59  */
  60 int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
  61 {
  62         void *ctx;
  63         u8 cbc[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE];
  64         u8 *pos = data;
  65         int i, j, blocks;
  66
  67         if (TEST_FAIL())
  68                 return -1;
  69
  70         ctx = aes_decrypt_init(key, 16);
  71         if (ctx == NULL)
  72                 return -1;
  73         os_memcpy(cbc, iv, AES_BLOCK_SIZE);
  74
  75         blocks = data_len / AES_BLOCK_SIZE;
  76         for (i = 0; i < blocks; i++) {
  77                 os_memcpy(tmp, pos, AES_BLOCK_SIZE);
  78                 aes_decrypt(ctx, pos, pos);
  79                 for (j = 0; j < AES_BLOCK_SIZE; j++)
  80                         pos[j] ^= cbc[j];
  81                 os_memcpy(cbc, tmp, AES_BLOCK_SIZE);
  82                 pos += AES_BLOCK_SIZE;
  83         }
  84         aes_decrypt_deinit(ctx);
  85         return 0;
  86 }