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* $Id: airpdcap_wep.c 20401 2007-01-12 00:54:13Z gerald $
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* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
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* Copyright (c) 2006 CACE Technologies, Davis (California)
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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/************************************************************************/
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#include <epan/tvbuff.h>
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#include <epan/crc32.h>
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#include "airpdcap_system.h"
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#include "airpdcap_int.h"
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#include "airpdcap_debug.h"
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/************************************************************************/
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/* Note: copied from FreeBSD source code, RELENG 6, */
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/* sys/net80211/ieee80211_crypto_wep.c, 391 */
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INT AirPDcapWepDecrypt(
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const size_t seed_len,
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const size_t data_len)
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/* Generate key stream (RC4 Pseude-Random Number Generator) */
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for (i = 0; i < 256; i++)
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for (j = i = 0; i < 256; i++) {
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j = (j + S[i] + seed[i % seed_len]) & 0xff;
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/* Apply RC4 to data and compute CRC32 over decrypted data */
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for (i = j = k = 0; k < buflen; k++) {
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j = (j + S[i]) & 0xff;
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*cypher_text ^= S[(S[i] + S[j]) & 0xff];
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crc = crc32_ccitt_table[(crc ^ *cypher_text) & 0xff] ^ (crc >> 8);
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/* Encrypt little-endian CRC32 and verify that it matches with the received ICV */
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icv[1] = (UINT8)(crc >> 8);
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icv[2] = (UINT8)(crc >> 16);
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icv[3] = (UINT8)(crc >> 24);
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for (k = 0; k < 4; k++) {
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j = (j + S[i]) & 0xff;
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if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *cypher_text++) {
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/* ICV mismatch - drop frame */
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return AIRPDCAP_RET_UNSUCCESS;
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return AIRPDCAP_RET_SUCCESS;
added
removed
epan/crypt/airpdcap_wep.c
