Java Tutorial/Security/Encrypt Decrypt

Blowfish Decrypt

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
public class MainClass {
  public static void main(String[] args) throws Exception {
    blowfishEncrypt("ciphertextfile", "plaintextfile");
  }
  public static void blowfishEncrypt(String f1, String f2) throws Exception {
    SecretKey key = null;
    ObjectInputStream keyFile = new ObjectInputStream(new FileInputStream("BlowfishKey.ser"));
    key = (SecretKey) keyFile.readObject();
    keyFile.close();
    Cipher cipher = Cipher.getInstance("Blowfish/ECB/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, key);
    CipherInputStream in = new CipherInputStream(new BufferedInputStream(new FileInputStream(f1)),
        cipher);
    BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(f2));
    int i;
    do {
      i = in.read();
      if (i != -1)
        out.write(i);
    } while (i > 0);
    in.close();
    out.close();
  }
}

Blowfish Encrypt

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
public class MainClass {
  public static void main(String[] args) throws Exception {
    blowfishEncrypt("plaintextfile", "ciphertextfile");
  }
  public static void blowfishEncrypt(String f1, String f2) throws Exception {
    SecretKey key = null;
    ObjectInputStream keyFile = new ObjectInputStream(new FileInputStream("BlowfishKey.ser"));
    key = (SecretKey) keyFile.readObject();
    keyFile.close();
    KeyGenerator keygen = KeyGenerator.getInstance("Blowfish");
    key = keygen.generateKey();
    ObjectOutputStream keyFileOut = new ObjectOutputStream(new FileOutputStream("BlowfishKey.ser"));
    keyFileOut.writeObject(key);
    keyFileOut.close();
    Cipher cipher = Cipher.getInstance("Blowfish/ECB/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, key);
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(f1));
    CipherOutputStream out = new CipherOutputStream(new BufferedOutputStream(new FileOutputStream(
        f2)), cipher);
    int i;
    do {
      i = in.read();
      if (i != -1)
        out.write(i);
    } while (i != -1);
    in.close();
    out.close();
  }
}

DES Encrypt Console

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
public class MainClass {
  public static void main(String[] args) throws Exception {
    desEncrypt("plaintextfile", "ciphertextfile");
  }
  public static void desEncrypt(String f1, String f2) throws Exception {
    SecretKey key = null;
    ObjectInputStream keyFile = new ObjectInputStream(new FileInputStream("DESKey.ser"));
    key = (SecretKey) keyFile.readObject();
    keyFile.close();
    KeyGenerator keygen = KeyGenerator.getInstance("DES");
    key = keygen.generateKey();
    ObjectOutputStream keyFileout = new ObjectOutputStream(new FileOutputStream("DESKey.ser"));
    keyFileout.writeObject(key);
    keyFileout.close();
    Cipher cipher = null;
    cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, key);
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(f1));
    CipherOutputStream out = new CipherOutputStream(new BufferedOutputStream(new FileOutputStream(
        f2)), cipher);
    int i;
    do {
      i = in.read();
      if (i != -1)
        out.write(i);
    } while (i != -1);
    in.close();
    out.close();
  }
}

Generate a random String suitable for use as a temporary password

/*
    JSPWiki - a JSP-based WikiWiki clone.
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
       http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.    
 */
import java.security.SecureRandom;
import java.util.Random;
public class StringUtils
{
  private static final Random RANDOM = new SecureRandom();
  /** Length of password. @see #generateRandomPassword() */
  public static final int PASSWORD_LENGTH = 8;
  /**
   * Generate a random String suitable for use as a temporary password.
   *
   * @return String suitable for use as a temporary password
   * @since 2.4
   */
  public static String generateRandomPassword()
  {
      // Pick from some letters that won"t be easily mistaken for each
      // other. So, for example, omit o O and 0, 1 l and L.
      String letters = "abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ23456789+@";
      String pw = "";
      for (int i=0; i<PASSWORD_LENGTH; i++)
      {
          int index = (int)(RANDOM.nextDouble()*letters.length());
          pw += letters.substring(index, index+1);
      }
      return pw;
  }
}

Use DES to Decrypt

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
public class MainClass {
  public static void main(String[] args) throws Exception {
    desEncrypt("plaintextfile", "ciphertextfile");
  }
  public static void desEncrypt(String f1, String f2) throws Exception {
    SecretKey key = null;
    ObjectInputStream keyFile = new ObjectInputStream(new FileInputStream("DESKey.ser"));
    key = (SecretKey) keyFile.readObject();
    keyFile.close();
    Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, key);
    CipherInputStream in = new CipherInputStream(new BufferedInputStream(new FileInputStream(f1)),
        cipher);
    BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(f2));
    int i;
    do {
      i = in.read();
      if (i != -1)
        out.write(i);
    } while (i > 0);
    in.close();
    out.close();
  }
}