JavaDESEncryption.java

package com.contextawareframework.security;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

public class JavaDESEncryption {

	private static Cipher encrypt;
	private static Cipher decrypt;

	private static final byte[] initialization_vector = { 22, 33, 11, 44, 55, 99, 66, 77 };

	public static void cryptFile(String filePath) {
		
		String clearFile = "/mnt/sdcard/Notes/contactbkp.db";//"C:/Users/nikos7/Desktop/input.txt";
		String encryptedFile = "/mnt/sdcard/Notes/contactbkpE.db";//"C:/Users/nikos7/Desktop/encrypted.txt";
		String decryptedFile = "/mnt/sdcard/Notes/contactbkpD.db";//"C:/Users/nikos7/Desktop/decrypted.txt";
//		String clearFile = "/home/prasenjit/Desktop/UploadFile/log.txt";//"C:/Users/nikos7/Desktop/input.txt";
//		String encryptedFile = "/home/prasenjit/Desktop/UploadFile/enc.txt";//"C:/Users/nikos7/Desktop/encrypted.txt";
//		String decryptedFile = "/home/prasenjit/Desktop/UploadFile/dec.txt";//"C:/Users/nikos7/Desktop/decrypted.txt";
		//File clearFile1 = new File("/mnt/sdcard/Notes/contactbkp.db");
		//File 
		try {

			SecretKey secret_key = KeyGenerator.getInstance("DES")
					.generateKey();
			AlgorithmParameterSpec alogrithm_specs = new IvParameterSpec(
					initialization_vector);

			// set encryption mode ...
			encrypt = Cipher.getInstance("DES/CBC/PKCS5Padding");
			encrypt.init(Cipher.ENCRYPT_MODE, secret_key, alogrithm_specs);

			// set decryption mode
			decrypt = Cipher.getInstance("DES/CBC/PKCS5Padding");
			decrypt.init(Cipher.DECRYPT_MODE, secret_key, alogrithm_specs);

			// encrypt file
			encrypt(new FileInputStream(clearFile), new FileOutputStream(
					encryptedFile));

			// decrypt file
			decrypt(new FileInputStream(encryptedFile), new FileOutputStream(
					decryptedFile));
			System.out.println("End of Encryption/Decryption procedure!");

		} catch (NoSuchAlgorithmException e )
		{
			e.printStackTrace();
		}
		catch(NoSuchPaddingException e)
		{
			e.printStackTrace();
		}
		catch(InvalidKeyException e)
		{
			e.printStackTrace();
		}
		catch(InvalidAlgorithmParameterException e) 
		{
			e.printStackTrace();
		}
		catch(IOException e) {
			e.printStackTrace();
		}

	}

	private static void encrypt(InputStream input, OutputStream output)
			throws IOException {

		output = new CipherOutputStream(output, encrypt);
		writeBytes(input, output);
	}

	private static void decrypt(InputStream input, OutputStream output)
			throws IOException {

		input = new CipherInputStream(input, decrypt);
		writeBytes(input, output);
	}

	private static void writeBytes(InputStream input, OutputStream output)
			throws IOException {
		byte[] writeBuffer = new byte[512];
		int readBytes = 0;

		while ((readBytes = input.read(writeBuffer)) >= 0) {
			output.write(writeBuffer, 0, readBytes);
		}

		output.close();
		input.close();
	}

}