/*
  Simple Implementation of Kerberos protocol v5
  Copyright (C) 2003 Thia Yeo Ching (tycordinal@yahoo.co.uk)

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2
  of the License, or (at your option) any later version.

  This program 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.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/



/*
Since this class combined the code found on 
http://javaalmanac.com , a permission is requested
from the website owners at xeo.com to make it GPLed
and include in this package:

==========================================
Date: Mon, 05 May 2003 15:31:54 -0700 
To: "tycordinal" <tycordinal@yahoo.co.uk> 
From: "Patrick Chan" <chan2002@xeo.com> 
Subject: Re: make portion of code GPLed 
       
 


you have my permission.

Thanks for asking.

cheers,
pat




At 09:50 AM 5/5/2003 +0100, you wrote:
>hi,
>
>I have made a small library at
>http://sourceforge.net/projects/javakerberos/ , to
>provide a simple kerberos implementation with RMI.
>However I haven't upload the code yet, since I got a
>small problem here: inside one of my classes I have
>combined the example code at
>http://javaalmanac.com/egs/javax.crypto/PassKey.html
>and
>http://javaalmanac.com/egs/javax.crypto/EncryptObject.html?l=rel
>.
>
>I hereby request permission for making combined
>portion of the above mentioned code available in my
>class and I promise making them GPLed. Please reply to
>me so that I can really do like that.
>
>Thank you very much.
>
>ps. Here is the class that make use of the
>combination:
>----------------(contents of this class)
============================================
*/

package SimpleKerberos.tool;

import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.KeySpec;

/**
 * Use DES for encrypy/decrypt
 */
public class NormalCryptor implements ICryptor
{
  Cipher ecipher;
  Cipher dcipher;

  // 8-byte Salt
  byte[] salt = {
    (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
    (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03
  };

  // Iteration count
  int iterationCount = 19;
  private static final String CRYPTOR_ALGO_NAME = "PBEWithMD5AndDES";


  public SealedObject encryptObject(Serializable obj)
  {
    SealedObject so = null;

    try
    {
      so = new SealedObject(obj, get_ecipher());
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return so;
  }

  public Object decryptObject(SealedObject so)
  {
    Object o = null;

    try
    {
      o = so.getObject(get_dcipher());
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return o;
  }

  public Cipher get_ecipher()
  {
    return ecipher;
  }

  public Cipher get_dcipher()
  {
    return dcipher;
  }

  /**
   * Encrypt/decrypt with the password
   * @param hashedClientPassword hashed value of client password;
   *   shall be the HashedPassword in authentication database.
   */
  public NormalCryptor(String hashedClientPassword)
  {
    try
    {
      // Create the key
      KeySpec keySpec = new PBEKeySpec(hashedClientPassword.toCharArray(), salt, iterationCount);
      SecretKey key = SecretKeyFactory.getInstance(
        CRYPTOR_ALGO_NAME).generateSecret(keySpec);
      ecipher = Cipher.getInstance(key.getAlgorithm());
      dcipher = Cipher.getInstance(key.getAlgorithm());

      // Prepare the parameter to the ciphers
      AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

      // Create the ciphers
      ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
      dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    }
    catch (java.security.InvalidAlgorithmParameterException e)
    {
      e.printStackTrace();
    }
    catch (java.security.spec.InvalidKeySpecException e)
    {
      e.printStackTrace();
    }
    catch (javax.crypto.NoSuchPaddingException e)
    {
      e.printStackTrace();
    }
    catch (java.security.NoSuchAlgorithmException e)
    {
      e.printStackTrace();
    }
    catch (java.security.InvalidKeyException e)
    {
      e.printStackTrace();
    }
  }

  public String encrypt(String str)
  {
    try
    {
      // Encode the string into bytes using utf-8
      byte[] utf8 = str.getBytes("UTF8");

      // Encrypt
      byte[] enc = ecipher.doFinal(utf8);

      // Encode bytes to base64 to get a string
      return new sun.misc.BASE64Encoder().encode(enc);
    }
    catch (javax.crypto.BadPaddingException e)
    {
      e.printStackTrace();
    }
    catch (IllegalBlockSizeException e)
    {
      e.printStackTrace();
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
    catch (java.io.IOException e)
    {
      e.printStackTrace();
    }
    return null;
  }

  /**
   *
   * @param str a string encrypted using encrypt()
   * @return a string if pass phrase is given correctly and no exception occured;
   *   otherwise null if passphrase given is not correct
   */
  public String decrypt(String str)
  {
    try
    {
      // Decode base64 to get bytes
      byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

      // Decrypt
      byte[] utf8 = dcipher.doFinal(dec);

      // Decode using utf-8
      return new String(utf8, "UTF8");
    }
    catch (BadPaddingException e)
    {
      e.printStackTrace();
    }
    catch (IllegalBlockSizeException e)
    {
      e.printStackTrace();
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
    catch (java.io.IOException e)
    {
      e.printStackTrace();
    }
    return null;
  }
}