diff options
Diffstat (limited to 'wsutil/airpdcap_wep.c')
-rw-r--r-- | wsutil/airpdcap_wep.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/wsutil/airpdcap_wep.c b/wsutil/airpdcap_wep.c new file mode 100644 index 0000000000..57b047fab7 --- /dev/null +++ b/wsutil/airpdcap_wep.c @@ -0,0 +1,102 @@ +/* airpcap_wep.c + * + * $Id$ + * + * 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. + */ + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +/************************************************************************/ +/* File includes */ + +#include <epan/tvbuff.h> +#include "crc32.h" + +/************************************************************************/ +/* Note: copied from net80211/ieee80211_airpdcap_tkip.c */ +#define S_SWAP(a,b) { guint8 t = S[a]; S[a] = S[b]; S[b] = t; } + +/* Note: copied from FreeBSD source code, RELENG 6, */ +/* sys/net80211/ieee80211_crypto_wep.c, 391 */ +int AirPDcapWepDecrypt( + const guchar *seed, + const size_t seed_len, + guchar *cypher_text, + const size_t data_len) +{ + guint32 i, j, k, crc; + guint8 S[256]; + guint8 icv[4]; + size_t buflen; + + /* Generate key stream (RC4 Pseudo-Random Number Generator) */ + for (i = 0; i < 256; i++) + S[i] = (guint8)i; + for (j = i = 0; i < 256; i++) { + j = (j + S[i] + seed[i % seed_len]) & 0xff; + S_SWAP(i, j); + } + + /* Apply RC4 to data and compute CRC32 over decrypted data */ + crc = ~(guint32)0; + buflen = data_len; + + for (i = j = k = 0; k < buflen; k++) { + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + *cypher_text ^= S[(S[i] + S[j]) & 0xff]; + crc = crc32_ccitt_table[(crc ^ *cypher_text) & 0xff] ^ (crc >> 8); + cypher_text++; + } + + crc = ~crc; + + /* Encrypt little-endian CRC32 and verify that it matches with the received ICV */ + icv[0] = (guint8)crc; + icv[1] = (guint8)(crc >> 8); + icv[2] = (guint8)(crc >> 16); + icv[3] = (guint8)(crc >> 24); + for (k = 0; k < 4; k++) { + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *cypher_text++) { + /* ICV mismatch - drop frame */ + return 1/*AIRPDCAP_RET_UNSUCCESS*/; + } + } + + return 0/*AIRPDCAP_RET_SUCCESS*/; +} |