/*
 * Copyright (C) 2011 www.itcsolutions.eu
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1, or (at your
 * option) any later version.
 *
 * This file 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.
 *
 *
 */

/**
 *
 * @author Catalin - www.itcsolutions.eu
 * @version dec 2011
 *
 */
import java.io.*;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.*;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class DES_ECB_CBC {
    Cipher eCipher;
    Cipher dCipher;

    // Buffer used to transport the bytes from one stream to another
    byte[] buf = new byte[8];       //input buffer - 8 bytes block
    byte[] obuf = new byte[1024];   //output buffer
    byte[] key = null;

    
    public DES_ECB_CBC()
            throws InvalidKeyException,
            NoSuchAlgorithmException,
            NoSuchPaddingException
    {
        key = "SECRET!!".getBytes();
        InitDESCiphersECBMode();
    }

    public DES_ECB_CBC(byte[] keyBytes)
            throws InvalidKeyException,
            NoSuchAlgorithmException,
            NoSuchPaddingException
    {
        key = new byte[keyBytes.length];
        System.arraycopy(keyBytes, 0 , key, 0, keyBytes.length);
        InitDESCiphersECBMode();
    }

    private void InitDESCiphersECBMode()
            throws InvalidKeyException,
            NoSuchAlgorithmException, 
            NoSuchPaddingException{
        eCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        dCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

        // ECB mode does NOT requires an initialization vector; only CBC mode
        eCipher.init(Cipher.ENCRYPT_MODE,
                new SecretKeySpec(key, 0, key.length, "DES"));
        dCipher.init(Cipher.DECRYPT_MODE,
                new SecretKeySpec(key, 0, key.length, "DES"));
    }

    private void InitDESCiphersCBCMode(byte[] iv)
            throws InvalidKeyException,
            NoSuchAlgorithmException,
            NoSuchPaddingException,
            InvalidAlgorithmParameterException{

        //set a default IV if not received
        if(iv == null)
            //the IV size is also 8 bytes  = size of a block
            iv = new byte[]{(byte)0x8E, 0x12, 0x39,
            (byte)0x9C,0x07, 0x72, 0x6F, 0x5A };

        IvParameterSpec ivparam = new IvParameterSpec(iv, 0, iv.length);

        eCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        dCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");

        // CBC requires an initialization vector
        eCipher.init(Cipher.ENCRYPT_MODE,
                new SecretKeySpec(key, 0, key.length, "DES"),ivparam);
        dCipher.init(Cipher.DECRYPT_MODE,
                new SecretKeySpec(key, 0, key.length, "DES"),ivparam);
    }

    public void encrypt(InputStream in, long length, OutputStream out)
    throws ShortBufferException, 
            IllegalBlockSizeException,
            BadPaddingException
    {
        try {
            // Bytes written to out will be encrypted
            // Read in the cleartext bytes and write to out to encrypt
            int numRead = 0;    //number of bytes read from input
            int numProc = 0;    //number of bytes processed
            long bytesToRead = length;

            while ((numRead = in.read(buf)) >= 0) {
                if (bytesToRead > buf.length)
                    numProc = eCipher.update(buf, 0, numRead, obuf, 0);
                else
                    numProc = eCipher.doFinal(buf, 0, numRead, obuf, 0);
                out.write(obuf, 0, numProc);
                bytesToRead-=numRead;
            }
            in.close();
            out.flush();
            out.close();
        }
        catch (java.io.IOException e) {
            System.out.println(e.getMessage());
        }
    }
    public void decrypt(InputStream in,long length, OutputStream out)
     throws ShortBufferException,
            IllegalBlockSizeException,
            BadPaddingException{
        try {
            // Bytes read from in will be decrypted
            // Read in the decrypted bytes and write the cleartext to out
            int numRead = 0;    //number of bytes read from input
            int numProc = 0;    //number of bytes processed
            long bytesToRead = length;

            while ((numRead = in.read(buf)) >= 0) {
                if (bytesToRead > buf.length)
                    numProc = dCipher.update(buf, 0, numRead, obuf, 0);
                else
                    numProc = dCipher.doFinal(buf, 0, numRead, obuf, 0);
                out.write(obuf, 0, numProc);
                bytesToRead-=numRead;
            }

            out.flush();
        } catch (java.io.IOException e) {
            System.out.println(e.getMessage());
        }
    }


}