package gnu.crypto.jce.cipher;

// --------------------------------------------------------------------------
// $Id: ARCFourSpi.java,v 1.2 2005/10/06 04:24:14 rsdio Exp $
//
// Copyright (C) 2002 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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.
//
// GNU Crypto 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.,
//    51 Franklin Street, Fifth Floor,
//    Boston, MA  02110-1301
//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module.  An independent module is a module which is
// not derived from or based on this library.  If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so.  If you do not wish to
// do so, delete this exception statement from your version.
//
// --------------------------------------------------------------------------

import gnu.crypto.Registry;
import gnu.crypto.prng.ARCFour;
import gnu.crypto.prng.IRandom;
import gnu.crypto.prng.LimitReachedException;
import gnu.crypto.prng.PRNGFactory;

import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;

import java.util.HashMap;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherSpi;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.ShortBufferException;

/**
 * The <i>Service Provider Interface</i> (<b>SPI</b>) for the ARCFOUR
 * stream cipher.
 *
 * @version $Revision: 1.2 $
 */
public class ARCFourSpi extends CipherSpi {

   // Constants and variables.
   // -----------------------------------------------------------------------

   private IRandom keystream;

   // Constructors.
   // -----------------------------------------------------------------------

   public ARCFourSpi() {
      super();
      keystream = PRNGFactory.getInstance(Registry.ARCFOUR_PRNG);
   }

   // Methods implementing CipherSpi.
   // -----------------------------------------------------------------------

   protected int engineGetBlockSize() {
      return 0; // stream cipher.
   }

   protected void engineSetMode(String s) throws NoSuchAlgorithmException {
      // ignored.
   }

   protected void engineSetPadding(String s) throws NoSuchPaddingException {
      // ignored.
   }

   protected byte[] engineGetIV() {
      return null;
   }

   protected int engineGetOutputSize(int in) {
      return in;
   }

   protected AlgorithmParameters engineGetParameters() {
      return null;
   }

   protected void engineInit(int mode, Key key, SecureRandom r)
   throws InvalidKeyException
   {
      if (mode != Cipher.ENCRYPT_MODE && mode != Cipher.DECRYPT_MODE) {
         throw new IllegalArgumentException("arcfour is for encryption or decryption only");
      }
      if (key == null || !key.getFormat().equalsIgnoreCase("RAW")) {
         throw new InvalidKeyException("key must be non-null raw bytes");
      }
      HashMap attrib = new HashMap();
      attrib.put(ARCFour.ARCFOUR_KEY_MATERIAL, key.getEncoded());
      keystream.init(attrib);
   }

   protected void engineInit(int mode, Key key,
      AlgorithmParameterSpec p, SecureRandom r)
   throws InvalidKeyException, InvalidAlgorithmParameterException
   {
      engineInit(mode, key, r);
   }

   protected void engineInit(int mode, Key key,
      AlgorithmParameters p, SecureRandom r)
   throws InvalidKeyException, InvalidAlgorithmParameterException
   {
      engineInit(mode, key, r);
   }

   protected byte[] engineUpdate(byte[] in, int offset, int length) {
      if (length < 0 || offset < 0 || length+offset > in.length) {
         throw new ArrayIndexOutOfBoundsException();
      }
      byte[] result = new byte[length];
      try {
         for (int i = 0; i < length; i++) {
            result[i] = (byte) (in[i+offset] ^ keystream.nextByte());
         }
      } catch (LimitReachedException wontHappen) { }
      return result;
   }

   protected int engineUpdate(byte[] in, int inOffset, int length,
      byte[] out, int outOffset) throws ShortBufferException
   {
      if (length < 0 || inOffset < 0 || length+inOffset > in.length
            || outOffset < 0) {
         throw new ArrayIndexOutOfBoundsException();
      }
      if (outOffset+length > out.length) {
         throw new ShortBufferException();
      }
      try {
         for (int i = 0; i < length; i++) {
            out[i+outOffset] = (byte) (in[i+inOffset] ^ keystream.nextByte());
         }
      } catch (LimitReachedException wontHappen) { }
      return length;
   }

   protected byte[] engineDoFinal(byte[] in, int offset, int length)
   throws IllegalBlockSizeException, BadPaddingException
   {
      return engineUpdate(in, offset, length);
   }

   protected int engineDoFinal(byte[] in, int inOffset, int length,
      byte[] out, int outOffset) throws ShortBufferException,
   IllegalBlockSizeException, BadPaddingException
   {
      return engineUpdate(in, inOffset, length, out, outOffset);
   }
}
