Android Open Source - AndroidLibraryProject Java D E S Encryption

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License

The source code is released under:

Apache License

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Java Source Code

package com.contextawareframework.security;
/*  www. j  a  v a  2s  .c om*/
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();
  }

}

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