Line data    Source code

       1             : /*
       2             :  * One-key CBC MAC (OMAC1) hash with AES-128
       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        1130 : static void gf_mulx(u8 *pad)
      17             : {
      18             :         int i, carry;
      19             : 
      20        1130 :         carry = pad[0] & 0x80;
      21       18080 :         for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
      22       16950 :                 pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
      23        1130 :         pad[AES_BLOCK_SIZE - 1] <<= 1;
      24        1130 :         if (carry)
      25         557 :                 pad[AES_BLOCK_SIZE - 1] ^= 0x87;
      26        1130 : }
      27             : 
      28             : 
      29             : /**
      30             :  * omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
      31             :  * @key: 128-bit key for the hash operation
      32             :  * @num_elem: Number of elements in the data vector
      33             :  * @addr: Pointers to the data areas
      34             :  * @len: Lengths of the data blocks
      35             :  * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
      36             :  * Returns: 0 on success, -1 on failure
      37             :  *
      38             :  * This is a mode for using block cipher (AES in this case) for authentication.
      39             :  * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
      40             :  * (SP) 800-38B.
      41             :  */
      42         566 : int omac1_aes_128_vector(const u8 *key, size_t num_elem,
      43             :                          const u8 *addr[], const size_t *len, u8 *mac)
      44             : {
      45             :         void *ctx;
      46             :         u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
      47             :         const u8 *pos, *end;
      48             :         size_t i, e, left, total_len;
      49             : 
      50         566 :         ctx = aes_encrypt_init(key, 16);
      51         566 :         if (ctx == NULL)
      52           0 :                 return -1;
      53         566 :         os_memset(cbc, 0, AES_BLOCK_SIZE);
      54             : 
      55         566 :         total_len = 0;
      56        1132 :         for (e = 0; e < num_elem; e++)
      57         566 :                 total_len += len[e];
      58         566 :         left = total_len;
      59             : 
      60         566 :         e = 0;
      61         566 :         pos = addr[0];
      62         566 :         end = pos + len[0];
      63             : 
      64        7237 :         while (left >= AES_BLOCK_SIZE) {
      65      103785 :                 for (i = 0; i < AES_BLOCK_SIZE; i++) {
      66       97680 :                         cbc[i] ^= *pos++;
      67       97680 :                         if (pos >= end) {
      68           2 :                                 e++;
      69           2 :                                 pos = addr[e];
      70           2 :                                 end = pos + len[e];
      71             :                         }
      72             :                 }
      73        6105 :                 if (left > AES_BLOCK_SIZE)
      74        6103 :                         aes_encrypt(ctx, cbc, cbc);
      75        6105 :                 left -= AES_BLOCK_SIZE;
      76             :         }
      77             : 
      78         566 :         os_memset(pad, 0, AES_BLOCK_SIZE);
      79         566 :         aes_encrypt(ctx, pad, pad);
      80         566 :         gf_mulx(pad);
      81             : 
      82         566 :         if (left || total_len == 0) {
      83        3456 :                 for (i = 0; i < left; i++) {
      84        2892 :                         cbc[i] ^= *pos++;
      85        2892 :                         if (pos >= end) {
      86         564 :                                 e++;
      87         564 :                                 pos = addr[e];
      88         564 :                                 end = pos + len[e];
      89             :                         }
      90             :                 }
      91         564 :                 cbc[left] ^= 0x80;
      92         564 :                 gf_mulx(pad);
      93             :         }
      94             : 
      95        9622 :         for (i = 0; i < AES_BLOCK_SIZE; i++)
      96        9056 :                 pad[i] ^= cbc[i];
      97         566 :         aes_encrypt(ctx, pad, mac);
      98         566 :         aes_encrypt_deinit(ctx);
      99         566 :         return 0;
     100             : }
     101             : 
     102             : 
     103             : /**
     104             :  * omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
     105             :  * @key: 128-bit key for the hash operation
     106             :  * @data: Data buffer for which a MAC is determined
     107             :  * @data_len: Length of data buffer in bytes
     108             :  * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
     109             :  * Returns: 0 on success, -1 on failure
     110             :  *
     111             :  * This is a mode for using block cipher (AES in this case) for authentication.
     112             :  * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
     113             :  * (SP) 800-38B.
     114             :  */
     115         566 : int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
     116             : {
     117         566 :         return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
     118             : }