/**
 * Dictionary generator/compressor for PPM (Password Probability Matrix).
 *
 * Creates and compresses (lossily) hashes for time-space tradeoff
 * brute-forcing. PoC only.
 *      
 * http://2600hacker.stores.yahoo.net/pasprobmat.html
**/

import java.security.NoSuchAlgorithmException;
import java.math.BigInteger;
import java.util.BitSet;
import java.io.*;

public class PPMGen {

	
    private static byte MIN_CHAR = 32;
    private static byte MAX_CHAR = 126;
    private static int  HASH_SIZE = 16*8192;
    private static int  CTMASK = 0x0001FFFF; // 17 bits

    private static BitSet [] ppm;
    static {
       ppm = new BitSet[ 95*95  ];
       for( int i = 0; i < ppm.length; i++ ) {
		ppm[ i ] = new BitSet( HASH_SIZE );
	}
    } 

    private static byte [] genHash( String password ) throws NoSuchAlgorithmException {
      return OneWayHash.hash( password ).getBytes();
    }

   private static int getIndex( byte c1, byte c2 ) {
	return ( c1 - MIN_CHAR )*95 + ( c2 - MIN_CHAR );
   }

   private static int computeCTIndex( byte [] b ) {
	int ret = byteArrayToInt( b, 0 );
	return ret & CTMASK;
   }

   private static int byteArrayToInt(byte[] b, int offset) {
        int value = 0;
        for (int i = 0; i < 4; i++) {
            int shift = (4 - 1 - i) * 8;
            value += (b[i + offset] & 0x000000FF) << shift;
        }
        return value;
    }

    public static void main( String [] args ) {
	try {
	byte [] plain = new byte[ 4 ];

	for( plain[ 0 ] = MIN_CHAR; plain[ 0 ] <= MAX_CHAR; plain[ 0 ]++ ) {
                System.out.print( "." );
		for( plain[ 1 ] = MIN_CHAR; plain[ 1 ] <= MAX_CHAR; plain[ 1 ]++ ) {
			for( plain[ 2 ] = MIN_CHAR; plain[ 2 ] <= MAX_CHAR; plain[ 2 ]++ ) {
				for( plain[ 3 ] = MIN_CHAR; plain[ 3 ] <= MAX_CHAR; plain[ 3 ]++ ) {
					int ptIndex = getIndex( plain[ 0 ], plain[ 1 ] );
				        int ctIndex = computeCTIndex( genHash( new String( plain ) ) );
                                        ppm[ ptIndex ].set( ctIndex );
				}
			}
		}
	}

	System.out.println( "\n[+] Done." );
	FileOutputStream fos = new FileOutputStream( "4char.ppm" );
	ObjectOutputStream oos = new ObjectOutputStream( fos );
	oos.writeObject( ppm );
	oos.close();
   } catch( Exception e ) {
	e.printStackTrace();
   }
  }
}