keygen.c

About WepDecrypt: Wepdecrypt is a Wireless LAN Tool written in c which guesses WEP Keys based o

/*******************************************************************************
* keygen.c
*	WEP Key Generators
*
* This program generates WEP keys using de facto standard key
* generators for 40 and 128 bit keys.
*
* Link against OpenSSL's libcrypto.a
*
* May 2001, Tim Newsham
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option) any later
* version. See http://www.fsf.org/copyleft/gpl.txt.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
********************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <openssl/md5.h>
#include "config.h"

//
// generate four subkeys from a seed using the defacto standard
//
void
wep_seedkeygen(int val, u_char *keys)
{
    int i;

    for(i = 0; i < WEPKEYSTORE; i++) {
        val *= 0x343fd;
        val += 0x269ec3;
        keys[i] = val >> 16;
    }
    return;
}

//
// generate one key from a string using the de facto standard
//
// resultant key is stored in
//   one 128 bit key: keys[0-15]
//
void
wep_keygen128(const char *str, u_char *keys)
{
    MD5_CTX ctx;
    u_char buf[64];
    int i, j;

    // repeat str until buf is full
    j = 0;
    for(i = 0; i < 64; i++) {
        if(str[j] == 0)
            j = 0;
        buf[i] = str[j++];
    }

    MD5_Init(&ctx);
    MD5_Update(&ctx, buf, sizeof buf);
    MD5_Final(buf, &ctx);

    memcpy(keys, buf, WEPKEYSTORE);
    for(i = 0; i < WEPSTRONGKEYSIZE; i++) {
        keys[i] = buf[i];
    }
    for(; i < WEPKEYSTORE; i++) {
        keys[i] = 0;
    }
    return;
}

//
// generate four subkeys from a string using the defacto standard
//
// resultant keys are stored in
//   four 40 bit keys: keys[0-4], keys[5-9], keys[10-14] and keys[15-20]
//
void
wep_keygen40(const char *str, u_char *keys)
{
    int val, i, shift;

    //
    // seed is generated by xor'ing in the keystring bytes
    // into the four bytes of the seed, starting at the little end
    ///
    val = 0;
    for(i = 0; str[i]; i++) {
        shift = i & 0x3;
        val ^= (str[i] << (shift * 8));
    }

    wep_seedkeygen(val, keys);
    return;
}

void
wep_keyprint(u_char *keys)
{
    int i;
    char sepchar;

    for(i = 0; i < WEPKEYSTORE; i++) {
        sepchar = (i % WEPKEYSIZE == WEPKEYSIZE - 1) ? '\n' : ':';
        printf("%02x%c", keys[i], sepchar);
    }
    return;
}