/*

 * AES Key Wrap Algorithm (RFC3394)

 *

 * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>

 *

 * This software may be distributed under the terms of the BSD license.

 * See README for more details.

 */

#include "includes.h"

#include "common.h"

#include "aes.h"

#include "aes_wrap.h"

/**

 * aes_wrap - Wrap keys with AES Key Wrap Algorithm (RFC3394)

 * @kek: Key encryption key (KEK)

 * @kek_len: Length of KEK in octets

 * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16

 * bytes

 * @plain: Plaintext key to be wrapped, n * 64 bits

 * @cipher: Wrapped key, (n + 1) * 64 bits

 * Returns: 0 on success, -1 on failure

 */

int aes_wrap(const u8 *kek, size_t kek_len, int n, const u8 *plain, u8 *cipher)

{

  u8 *a, *r, b[AES_BLOCK_SIZE];

  int i, j;

  void *ctx;

  unsigned int t;

  a = cipher;

  r = cipher + 8;

  /* 1) Initialize variables. */

  os_memset(a, 0xa6, 8);

  os_memcpy(r, plain, 8 * n);

  ctx = aes_encrypt_init(kek, kek_len);

  if (ctx == NULL)

    return -1;

  /* 2) Calculate intermediate values.

   * For j = 0 to 5

   *     For i=1 to n

   *         B = AES(K, A | R[i])

   *         A = MSB(64, B) ^ t where t = (n*j)+i

   *         R[i] = LSB(64, B)

   */

  for (j = 0; j <= 5; j++) {

    r = cipher + 8;

    for (i = 1; i <= n; i++) {

      os_memcpy(b, a, 8);

      os_memcpy(b + 8, r, 8);

      aes_encrypt(ctx, b, b);

      os_memcpy(a, b, 8);

      t = n * j + i;

      a[7] ^= t;

      a[6] ^= t >> 8;

      a[5] ^= t >> 16;

      a[4] ^= t >> 24;

      os_memcpy(r, b + 8, 8);

      r += 8;

    }

  }

  aes_encrypt_deinit(ctx);

  /* 3) Output the results.

   *

   * These are already in @cipher due to the location of temporary

   * variables.

   */

  return 0;

}