epan/crypt/airpdcap_rijndael.c

   1 /**
   2  * airpdcap_rijndael.c
   3  *
   4  * $Id$
   5  *
   6  * @version 3.0 (December 2000)
   7  *
   8  * Optimised ANSI C code for the Rijndael cipher (now AES)
   9  *
  10  * @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
  11  * @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
  12  * @author Paulo Barreto <paulo.barreto@terra.com.br>
  13  *
  14  * This code is hereby placed in the public domain.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
  17  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
  20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  23  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  24  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  25  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  26  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /******************************************************************************/
  30 /*      File includes                                                                                                                                                                   */
  31 /*                                                                                                                                                                                                              */
  32 #include "airpdcap_rijndael.h"
  33
  34 #include        "airpdcap_debug.h"
  35 #include <glib.h>
  36 #include <wsutil/aes.h>
  37
  38 /* Based on RFC 3394 and NIST AES Key Wrap Specification pseudo-code.
  39
  40 This function is used to unwrap an encrypted AES key.  One example of its use is
  41 in the WPA-2 protocol to get the group key.
  42 */
  43 UCHAR
  44 AES_unwrap(UCHAR *kek, UINT16 key_len, UCHAR *cipher_text, UINT16 cipher_len, UCHAR *output)
  45 {
  46         UCHAR a[8], b[16];
  47         UCHAR *r;
  48         UCHAR *c;
  49         gint16 i, j, n;
  50         rijndael_ctx  ctx;
  51
  52         if (! kek || cipher_len < 16 || ! cipher_text || ! output) {
  53                 return 1; /* We don't do anything with the return value */
  54         }
  55
  56         /* Initialize variables */
  57
  58         n = (cipher_len/8)-1;  /* the algorithm works on 64-bits at a time */
  59         memcpy(a, cipher_text, 8);
  60         r = output;
  61         c = cipher_text;
  62         memcpy(r, c+8, cipher_len - 8);
  63
  64         /* Compute intermediate values */
  65
  66         for (j=5; j >= 0; --j){
  67                 r = output + (n - 1) * 8;
  68                 /* DEBUG_DUMP("r1", (r-8), 8); */
  69                 /* DEBUG_DUMP("r2", r, 8); */
  70                 for (i = n; i >= 1; --i){
  71                         UINT16 t = (n*j) + i;
  72                         /* DEBUG_DUMP("a", a, 8); */
  73                         memcpy(b, a, 8);
  74                         b[7] ^= t;
  75                         /* DEBUG_DUMP("a plus t", b, 8); */
  76                         memcpy(b+8, r, 8);
  77                         rijndael_set_key(&ctx, kek, key_len*8 /*bits*/);
  78                         rijndael_decrypt(&ctx, b, b);  /* NOTE: we are using the same src and dst buffer. It's ok. */
  79                         /* DEBUG_DUMP("aes decrypt", b, 16) */
  80                         memcpy(a,b,8);
  81                         memcpy(r, b+8, 8);
  82                         r -= 8;
  83                 }
  84         }
  85
  86         /* DEBUG_DUMP("a", a, 8); */
  87         /* DEBUG_DUMP("output", output, cipher_len - 8); */
  88
  89         return 0;
  90 }
  91
  92 /*                                                                                                                                                                                                              */
  93 /******************************************************************************/