wkeygen.c

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

/*
 * wkeygen.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
 *
 * I place this code in the public domain.
 * May 2001, Tim Newsham
 * May 2006, Fernando Tarin
 */

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

#include "config.h"

#define WEPKEYSIZE      	5
#define WEPSTRONGKEYSIZE	13
#define WEPKEYS         	4
#define WEPKEYSTORE     	(WEPKEYSIZE * WEPKEYS)
#define WEPSTRONGKEYSTORE	(WEPSTRONGKEYSIZE * WEPKEYS)
#define TAM_LINE 		25
#define ERROR 			0
#define OK 			1

/*
 * gets a line from file stream if TAM_LINE is exceeded an error is raised
 */
int 
get_line (char * line, FILE * stream)
{
	int i=0;
	
	while (i < (TAM_LINE-1) && (line[i] = fgetc(stream)) != '\n') i++;
	line[i] = '\0';
	
	if (i == (TAM_LINE-1)) return ERROR;
	else return OK;
}

/*
 * 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]
 *
 * (NOTE: I'm not sure why, but it seems that only values 0-12 are used,
 * resulting in 104 bits of keying, not 128)
 */
void
wep_keygen128(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, WEPSTRONGKEYSTORE);
    for(i = 0; i < WEPSTRONGKEYSIZE; i++) {
        keys[i] = buf[i];
    }
    //for(; i < WEPSTRONGKEYSTORE; 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(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_keyprint40(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;
}

void
wep_keyprint128(u_char *keys)
{
    int i;
    char sepchar;

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

void
usage(char *prog)
{
    printf("Usage:  %s -i [-s] | [-s] keystring\n", prog);
    printf("\t -i reads keystring from stdin\n");
    printf("\t -s generates a 128 wepkey default is 64 wepkey\n");
	printf("\nThis tool is part from Wepdecrypt project - Version %s\n", VERSION);
	printf("http://wepdecrypt.sourceforge.net/\n");
    exit(1);
}

int
main(int argc, char **argv) 
{
    u_char keys[WEPKEYSTORE];
    u_char strongkeys[WEPSTRONGKEYSTORE];
    char *prog, *genstr, keystr[TAM_LINE];
    int strong, ch, readstdin;

    prog = argv[0];
    strong = readstdin = 0;

    if (argc == 1) usage(prog);
	
    while((ch = getopt(argc, argv, "is")) != EOF) {
        switch(ch) {
        case 's':
		if (argc == 2) usage(prog);
        	    strong ++;
	            break;
	case 'i':
		if (strong || (argc > 2 && (strncmp(argv[2],"-s",2) != 0)) || argc > 3 || ((strncmp(argv[1],"-i",2) != 0) && (strncmp(argv[1],"-s",2) != 0))) usage(prog);
		readstdin++;
		break;
        default:
            usage(prog);
        }
    }

    if (readstdin) {
    	//while (fscanf(stdin, "%s", keystr) != EOF){
	while (1){
		get_line(keystr, stdin);
		if (keystr[0] == EOF) break;
		genstr = keystr;
		if(strong)
		{
			wep_keygen128(genstr, strongkeys);
			wep_keyprint128(strongkeys);
		}
		else				
		{
			wep_keygen40(genstr, keys);
			wep_keyprint40(keys);
		}
	}
    }


    else{
    	if(strong)			
    	{	
		genstr = argv[2];
		wep_keygen128(genstr, strongkeys);
      		wep_keyprint128(strongkeys);
 	}
	else
    	{
		genstr = argv[1];
        	wep_keygen40(genstr, keys);
	       	wep_keyprint40(keys);
    	}
	
    }

    return 0;
}