Line data    Source code

       1             : /*
       2             :  * AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
       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_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
      18             :  * @kek: 16-octet Key encryption key (KEK)
      19             :  * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
      20             :  * bytes
      21             :  * @plain: Plaintext key to be wrapped, n * 64 bits
      22             :  * @cipher: Wrapped key, (n + 1) * 64 bits
      23             :  * Returns: 0 on success, -1 on failure
      24             :  */
      25         666 : int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
      26             : {
      27             :         u8 *a, *r, b[16];
      28             :         int i, j;
      29             :         void *ctx;
      30             : 
      31         666 :         a = cipher;
      32         666 :         r = cipher + 8;
      33             : 
      34             :         /* 1) Initialize variables. */
      35         666 :         os_memset(a, 0xa6, 8);
      36         666 :         os_memcpy(r, plain, 8 * n);
      37             : 
      38         666 :         ctx = aes_encrypt_init(kek, 16);
      39         666 :         if (ctx == NULL)
      40           0 :                 return -1;
      41             : 
      42             :         /* 2) Calculate intermediate values.
      43             :          * For j = 0 to 5
      44             :          *     For i=1 to n
      45             :          *         B = AES(K, A | R[i])
      46             :          *         A = MSB(64, B) ^ t where t = (n*j)+i
      47             :          *         R[i] = LSB(64, B)
      48             :          */
      49        4662 :         for (j = 0; j <= 5; j++) {
      50        3996 :                 r = cipher + 8;
      51       32490 :                 for (i = 1; i <= n; i++) {
      52       28494 :                         os_memcpy(b, a, 8);
      53       28494 :                         os_memcpy(b + 8, r, 8);
      54       28494 :                         aes_encrypt(ctx, b, b);
      55       28494 :                         os_memcpy(a, b, 8);
      56       28494 :                         a[7] ^= n * j + i;
      57       28494 :                         os_memcpy(r, b + 8, 8);
      58       28494 :                         r += 8;
      59             :                 }
      60             :         }
      61         666 :         aes_encrypt_deinit(ctx);
      62             : 
      63             :         /* 3) Output the results.
      64             :          *
      65             :          * These are already in @cipher due to the location of temporary
      66             :          * variables.
      67             :          */
      68             : 
      69         666 :         return 0;
      70             : }