/*	DESEncryption.java
*	@author: Charles Bell
*	@version: Feb 28, 2001
*/

import java.io.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.interfaces.*;
import javax.crypto.spec.*;
import com.sun.crypto.provider.SunJCE; 


public class DESEncryption{

	String message = "George W. Bush is the president of the United States of America.";
	Cipher desCipher;
	SecretKey desKey;


	public static void main(String[] args){

		DESEncryption desencryption = new DESEncryption();
		// Add SunJCE to the list of providers 
		SunJCE jce = new SunJCE(); 
		Security.addProvider(jce); 

		desencryption.init();
		desencryption.test1();
		desencryption.test2();
		desencryption.test3();
		desencryption.test4();
	}

	public void init(){
		try{
			System.out.println("Initializing Cipher and keys. Standby...");
			KeyGenerator keygenerator = KeyGenerator.getInstance("DES");
			desKey = keygenerator.generateKey();
			desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
			System.out.println("Cipher and keys initialized.");
		}catch(NoSuchAlgorithmException nsae){
			System.out.println("NoSuchAlgorithmException:" + nsae.getMessage());
		}catch(NoSuchPaddingException nspe){
			System.out.println("NoSuchPaddingException:" + nspe.getMessage());
		}
	}

	public void test1(){
		try{
		System.out.println("test 1");
			System.out.println(message);
  	  		desCipher.init(Cipher.ENCRYPT_MODE, desKey);
			byte[] encryptedbytes = desCipher.doFinal(message.getBytes());
	    		desCipher.init(Cipher.DECRYPT_MODE, desKey);
    			byte[] plainbytes = desCipher.doFinal(encryptedbytes);
			System.out.println(new String(encryptedbytes));
			System.out.println(new String(plainbytes));
		}catch(InvalidKeyException ike){
			System.out.println("InvalidKeyException:" + ike.getMessage());
		}catch(IllegalBlockSizeException ibse){
			System.out.println("IllegalBlockSizeException:" + ibse.getMessage());
		}catch(BadPaddingException bpe){
			System.out.println("BadPaddingException: 222" + bpe.getMessage());
		}
	}

	public void test2(){
		System.out.println("test 2");
		System.out.println(new String(decrypt(encrypt(message.getBytes()))));
	}

	
	public void test3(){
		System.out.println("test 3");
		byte[] b1 = message.getBytes();
		System.out.println(new String(b1));
		byte[] b2 = encrypt(b1);
		System.out.println(new String(b2));
		byte[] b3 = decrypt(b2);
		System.out.println(new String(b3));
	}

	/**  	Encrypts an arbitrary file, decrypts to a new file same 
	*	which has the same bytes.*/	
	public void test4(){
		try{
			File file = new File("Saturn.gif"); //change your file here
			long filelength = file.length();
			FileInputStream fis = new FileInputStream(file);
			DataInputStream dis = new DataInputStream(fis);
			byte[] inputbuffer = new byte[(int)filelength];
			for (int i = 0;i < (int)filelength;i++){
				inputbuffer[i] = dis.readByte();
			}
			byte[] b1 = inputbuffer;
			byte[] b2 = encrypt(b1);
			FileOutputStream fos1 = new FileOutputStream("Saturn.enc");
			DataOutputStream dos1 = new DataOutputStream(fos1);
			for (int i = 0;i < b2.length;i++){
				dos1.write(b2[i]);
			}
			fos1.close();
			byte[] b3 = decrypt(b2);
			FileOutputStream fos2 = new FileOutputStream("SaturnNew.gif");
			DataOutputStream dos2 = new DataOutputStream(fos2);

			for (int i = 0;i < b3.length;i++){
				dos2.write(b3[i]);
			}
			fos2.close();
			
		}catch(IOException ioe){
			System.out.println("IOException: " + ioe.getMessage());
		}
	}

	public byte[] encrypt(byte[] b){
		byte[] encryptedbytes = b;
		try{
  			desCipher.init(Cipher.ENCRYPT_MODE, desKey);
			encryptedbytes = desCipher.doFinal(b);
		}catch(InvalidKeyException ike){
			System.out.println("InvalidKeyException:" + ike.getMessage());
		}catch(IllegalBlockSizeException ibse){
			System.out.println("IllegalBlockSizeException:" + ibse.getMessage());
		}catch(BadPaddingException bpe){
			System.out.println("BadPaddingException: 222" + bpe.getMessage());
		}
		return encryptedbytes;		
	}

	public byte[] decrypt(byte[] b){
		byte[] decryptedbytes = b;
		try{
  			desCipher.init(Cipher.DECRYPT_MODE, desKey);
			decryptedbytes = desCipher.doFinal(b);
		}catch(InvalidKeyException ike){
			System.out.println("InvalidKeyException:" + ike.getMessage());
		}catch(IllegalBlockSizeException ibse){
			System.out.println("IllegalBlockSizeException:" + ibse.getMessage());
		}catch(BadPaddingException bpe){
			System.out.println("BadPaddingException: 222" + bpe.getMessage());
		}
		return decryptedbytes;		
	}
	
}