package security;

import javax.crypto.*;
import java.security.*;
import java.io.*;

public class DesEncrypter
{
  private Cipher ecipher;
  private Cipher dcipher;

  public DesEncrypter(File keyFile) throws IOException, ClassNotFoundException
  {
    try
    {
      FileInputStream fis = new FileInputStream(keyFile);
      ObjectInputStream ois = new ObjectInputStream(fis);

      SecretKey key = (SecretKey)ois.readObject();
      ois.close();

      ecipher = Cipher.getInstance("DES");
      dcipher = Cipher.getInstance("DES");
      ecipher.init(Cipher.ENCRYPT_MODE, key);
      dcipher.init(Cipher.DECRYPT_MODE, key);   
    }
    catch (javax.crypto.NoSuchPaddingException e)
    {
      e.printStackTrace();
    }
    catch (java.security.NoSuchAlgorithmException e)
    {
      e.printStackTrace();
    }
    catch (java.security.InvalidKeyException e)
    {
      e.printStackTrace();
    }
  }
    
  public DesEncrypter(SecretKey key)
  {
    try
    {
      ecipher = Cipher.getInstance("DES");
      dcipher = Cipher.getInstance("DES");
      ecipher.init(Cipher.ENCRYPT_MODE, key);
      dcipher.init(Cipher.DECRYPT_MODE, key);
    }
    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 (Exception e)
    {
      e.printStackTrace();
    }

    return null;
  }
    
  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 (Exception e)
    {
      e.printStackTrace();
    }

    return null;
  }
}