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airpdcap_rijndael.c

/**
 * airpdcap_rijndael.c
 *
 * $Id: airpdcap_rijndael.c 29228 2009-07-29 10:01:14Z sahlberg $
 *
 * @version 3.0 (December 2000)
 *
 * Optimised ANSI C code for the Rijndael cipher (now AES)
 *
 * @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
 * @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
 * @author Paulo Barreto <paulo.barreto@terra.com.br>
 *
 * This code is hereby placed in the public domain.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/******************************************************************************/
/*    File includes                                                                                                                             */
/*                                                                                                                                                          */
#include "airpdcap_rijndael.h"

#include    "airpdcap_debug.h"
#include <glib.h>
#include "crypt-aes.h"

/* Based on RFC 3394 and NIST AES Key Wrap Specification pseudo-code.

This function is used to unwrap an encrypted AES key.  One example of its use is
in the WPA-2 protocol to get the group key.
*/
UCHAR
AES_unwrap(UCHAR *kek, UINT16 key_len, UCHAR *cipher_text, UINT16 cipher_len, UCHAR *output)
{
      UCHAR a[8], b[16];
      UCHAR *r;
      UCHAR *c;
      gint16 i, j, n;
      rijndael_ctx  ctx;

      if (! kek || cipher_len < 16 || ! cipher_text || ! output) {
            return 1; /* We don't do anything with the return value */
      }

      /* Initialize variables */

      n = (cipher_len/8)-1;  /* the algorithm works on 64-bits at a time */
      memcpy(a, cipher_text, 8);
      r = output;
      c = cipher_text;
      memcpy(r, c+8, cipher_len - 8);

      /* Compute intermediate values */

      for (j=5; j >= 0; --j){
            r = output + (n - 1) * 8;
            /* DEBUG_DUMP("r1", (r-8), 8); */
            /* DEBUG_DUMP("r2", r, 8); */
            for (i = n; i >= 1; --i){
                  UINT16 t = (n*j) + i;
                  /* DEBUG_DUMP("a", a, 8); */
                  memcpy(b, a, 8);
                  b[7] ^= t;
                  /* DEBUG_DUMP("a plus t", b, 8); */
                  memcpy(b+8, r, 8);
                  rijndael_set_key(&ctx, kek, key_len*8 /*bits*/);
                  rijndael_decrypt(&ctx, b, b);  /* NOTE: we are using the same src and dst buffer. It's ok. */
                  /* DEBUG_DUMP("aes decrypt", b, 16) */
                  memcpy(a,b,8);
                  memcpy(r, b+8, 8);
                  r -= 8;
            }
      }

      /* DEBUG_DUMP("a", a, 8); */
      /* DEBUG_DUMP("output", output, cipher_len - 8); */

      return 0;
}

/*                                                                                                                                                          */
/******************************************************************************/

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