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airpdcap_tkip.c

/*
 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
 * Copyright (c) 2006 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/* $Id: airpdcap_tkip.c 25879 2008-07-30 22:32:21Z gerald $ */

/******************************************************************************/
/*    File includes                                                                                                                             */
/*                                                                                                                                                          */
#include <epan/pint.h>
#include "airpdcap_system.h"
#include "airpdcap_int.h"

#include "airpdcap_debug.h"
/*                                                                                                                                                          */
/******************************************************************************/

/******************************************************************************/
/*    Internal definitions                                                                                                                */
/*                                                                                                                                                          */
#define PHASE1_LOOP_COUNT     8

#define AIRPDCAP_TTAK_LEN     6
/*                                                                                                                                                          */
/******************************************************************************/

/******************************************************************************/
/*    Internal function prototypes declarations                                                                   */
/*                                                                                                                                                          */
void AirPDcapTkipMixingPhase1(
      UINT16 *TTAK,
      const UINT8 *TK,
      const UINT8 *TA,
      UINT32 TSC)
      ;

static void AirPDcapTkipMixingPhase2(
      UINT8 *wep_seed,
      const UINT8 *TK,
      UINT16 *PPK,
      UINT16 TSC16)
      ;

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

/******************************************************************************/
/*    Global variables                                                                                                                    */
/*                                                                                                                                                          */
/* Note: copied from FreeBSD source code, RELENG 6,                                                   */
/*          sys/net80211/ieee80211_crypto_tkip.c, 471                                                             */
static const UINT16 Sbox[256] = {
      0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
      0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
      0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
      0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
      0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
      0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
      0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
      0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
      0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
      0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
      0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
      0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
      0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
      0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
      0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
      0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
      0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
      0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
      0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
      0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
      0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
      0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
      0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
      0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
      0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
      0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
      0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
      0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
      0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
      0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
      0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
      0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
};
/*                                                                                                                                                          */
/******************************************************************************/

/* TODO: check for little-endian, big-endian    */

/*                                                                                                                                                          */
/* Note: any functions were copied from FreeBSD source code, RELENG 6,              */
/*          sys/net80211/ieee80211_crypto_tkip.c                                                                        */
/* Converted to macros to avoid using __inline, as not all compilers support it     */
#define RotR1(val)      ((UINT16)(((val) >> 1) | ((val) << 15)))

#define Lo8(val)  ((UINT8)((val) & 0xff))

#define Hi8(val)  ((UINT8)((val) >> 8))

#define Lo16(val) ((UINT16)((val) & 0xffff))

#define Hi16(val) ((UINT16)((val) >> 16))

#define Mk16(hi, lo) \
      ((UINT16)((lo) | (((UINT16) (hi)) << 8)))

#define Mk16_le(v)      ((UINT16)pletohs(v))

#define _S_(v) \
      ((UINT16)(Sbox[Lo8(v)] ^ ((Sbox[Hi8(v)] << 8) | (Sbox[Hi8(v)] >> 8))))

#define READ_6(b0, b1, b2, b3, b4, b5) \
      ((((UINT64)((UINT16)((b4 << 0) | (b5 << 8)))) << 32) | \
          ((UINT32)((b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24))))

/******************************************************************************/
/*    Function definitions                                                                                                                */

void AirPDcapTkipMixingPhase1(
      UINT16 *TTAK,
      const UINT8 *TK,
      const UINT8 *TA,
      UINT32 TSC)
{
      UINT16 i, j;

      /* Initialize the 80-bit TTAK from TSC (TSC) and TA[0..5] */
      TTAK[0] = Lo16(TSC);
      TTAK[1] = Hi16(TSC);
      TTAK[2] = Mk16(TA[1], TA[0]);
      TTAK[3] = Mk16(TA[3], TA[2]);
      TTAK[4] = Mk16(TA[5], TA[4]);

      for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
            j = (UINT16)(2 * (i & 1));
            TTAK[0] = (UINT16)(TTAK[0] + _S_((UINT16)(TTAK[4] ^ Mk16(TK[1 + j], TK[0 + j]))));
            TTAK[1] = (UINT16)(TTAK[1] + _S_((UINT16)(TTAK[0] ^ Mk16(TK[5 + j], TK[4 + j]))));
            TTAK[2] = (UINT16)(TTAK[2] + _S_((UINT16)(TTAK[1] ^ Mk16(TK[9 + j], TK[8 + j]))));
            TTAK[3] = (UINT16)(TTAK[3] + _S_((UINT16)(TTAK[2] ^ Mk16(TK[13 + j], TK[12 + j]))));
            TTAK[4] = (UINT16)(TTAK[4] + _S_((UINT16)(TTAK[3] ^ Mk16(TK[1 + j], TK[0 + j]))) + i);
      }
}

static void AirPDcapTkipMixingPhase2(
      UINT8 *wep_seed,
      const UINT8 *TK,
      UINT16 *TTAK,
      UINT16 TSC16)
{
      INT i;
      TTAK[5] = (UINT16)(TTAK[4] + TSC16);

      /* Step 2 - 96-bit bijective mixing using S-box */
      TTAK[0] = (UINT16)(TTAK[0] + _S_((UINT16)(TTAK[5] ^ Mk16_le(&TK[0]))));
      TTAK[1] = (UINT16)(TTAK[1] + _S_((UINT16)(TTAK[0] ^ Mk16_le(&TK[2]))));
      TTAK[2] = (UINT16)(TTAK[2] + _S_((UINT16)(TTAK[1] ^ Mk16_le(&TK[4]))));
      TTAK[3] = (UINT16)(TTAK[3] + _S_((UINT16)(TTAK[2] ^ Mk16_le(&TK[6]))));
      TTAK[4] = (UINT16)(TTAK[4] + _S_((UINT16)(TTAK[3] ^ Mk16_le(&TK[8]))));
      TTAK[5] = (UINT16)(TTAK[5] + _S_((UINT16)(TTAK[4] ^ Mk16_le(&TK[10]))));

      TTAK[0] = (UINT16)(TTAK[0] + RotR1((UINT16)(TTAK[5] ^ Mk16_le(&TK[12]))));
      TTAK[1] = (UINT16)(TTAK[1] + RotR1((UINT16)(TTAK[0] ^ Mk16_le(&TK[14]))));
      TTAK[2] = (UINT16)(TTAK[2] + RotR1(TTAK[1]));
      TTAK[3] = (UINT16)(TTAK[3] + RotR1(TTAK[2]));
      TTAK[4] = (UINT16)(TTAK[4] + RotR1(TTAK[3]));
      TTAK[5] = (UINT16)(TTAK[5] + RotR1(TTAK[4]));

      /* Step 3 - bring in last of TK bits, assign 24-bit WEP IV value
      * wep_seed[0..2] is transmitted as WEP IV */
      wep_seed[0] = Hi8(TSC16);
      wep_seed[1] = (UINT8)((Hi8(TSC16) | 0x20) & 0x7F);
      wep_seed[2] = Lo8(TSC16);
      wep_seed[3] = Lo8((UINT16)((TTAK[5] ^ Mk16_le(&TK[0])) >> 1));

      for (i = 0; i < 6; i++)
      {
            wep_seed[4 + ( 2 * i)] = Lo8( TTAK[i] );
            wep_seed[5 + ( 2 * i)] = Hi8( TTAK[i] );
      }
}

/* Note: taken from FreeBSD source code, RELENG 6,                                                          */
/*          sys/net80211/ieee80211_crypto_tkip.c, 936                                                             */
INT AirPDcapTkipDecrypt(
      UCHAR *tkip_mpdu,
      size_t mpdu_len,
      UCHAR TA[AIRPDCAP_MAC_LEN],
      UCHAR TK[AIRPDCAP_TK_LEN])
{
      UINT64 TSC64;
      UINT32 TSC;
      UINT16 TSC16;
      UINT8 *IV;
      UINT16 TTAK[AIRPDCAP_TTAK_LEN];
      UINT8 wep_seed[AIRPDCAP_WEP_128_KEY_LEN];

      /* DEBUG_DUMP("TA", TA, 6); */

      IV = tkip_mpdu;

      TSC64 = READ_6(IV[2], IV[0], IV[4], IV[5], IV[6], IV[7]);
      TSC16 = (UINT16)TSC64;

      /* The original code made no sense!!  We were shifting a 16-bit number 16 bits to the right. */
      /* We instead have to have READ_6() be returned to a UINT64 and shift *that* value. */
      TSC = (UINT32)(TSC64 >> 16);

      AirPDcapTkipMixingPhase1(TTAK, TK, TA, TSC);

      AirPDcapTkipMixingPhase2(wep_seed, TK, TTAK, TSC16);

      return AirPDcapWepDecrypt(
            wep_seed,
            AIRPDCAP_WEP_128_KEY_LEN,
            tkip_mpdu + AIRPDCAP_TKIP_HEADER,
            mpdu_len-(AIRPDCAP_TKIP_HEADER+AIRPDCAP_WEP_ICV));    /* MPDU - TKIP_HEADER - MIC   */

      /* TODO check (IEEE 802.11i-2004, pg. 44)                                                                   */

}
/*                                                                                                                                                          */
/******************************************************************************/

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