package gnu.crypto.sasl.srp;

// ----------------------------------------------------------------------------
// $Id: IALG.java,v 1.5 2005/10/06 04:24:18 rsdio Exp $
//
// Copyright (C) 2003 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, 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; see the file COPYING.  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.mac.IMac;
import gnu.crypto.mac.MacFactory;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;

import javax.security.sasl.SaslException;

/**
 * <p>A Factory class that returns IALG (Integrity Algorithm) instances that
 * operate as described in the draft-burdis-cat-sasl-srp-04 and later.</p>
 *
 * @version $Revision: 1.5 $
 */
public final class IALG implements Cloneable {

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

   private IMac hmac;

	// Constructor(s)
	// --------------------------------------------------------------------------

	/** Private constructor to enforce instantiation through Factory method. */
	private IALG(final IMac hmac) {
		super();

		this.hmac = hmac;
	}

	// Class methods
	// -------------------------------------------------------------------------

   /**
    * <p>Returns an instance of a SASL-SRP IALG implementation.</p>
    *
    * @param algorithm the name of the HMAC algorithm.
    * @return an instance of this object.
    */
   static synchronized IALG getInstance(final String algorithm)
   throws SaslException {
	   final IMac hmac;
      hmac = MacFactory.getInstance(algorithm);
      if (hmac == null) {
         throw new SaslException("getInstance()", new NoSuchAlgorithmException(algorithm));
      }
// 	   try {
//         byte[] sk = (byte[]) K.clone();
//         HashMap map = new HashMap();
//         map.put(IMac.MAC_KEY_MATERIAL, sk);
//         hmac.init(map);
// 	   } catch (InvalidKeyException x) {
//   	   throw new SaslException("getInstance()", x);
// 	   }
      return new IALG(hmac);
   }

	// Instance methods
	// -------------------------------------------------------------------------

   // Cloneable interface implementation --------------------------------------

   public Object clone() throws CloneNotSupportedException {
      return new IALG((IMac) hmac.clone());
   }

   // other methdds -----------------------------------------------------------

//   public void init(final byte[] K) throws SaslException {
   public void init(final KDF kdf) throws SaslException {
 	   try {
//         final byte[] sk = (byte[]) K.clone();
         final byte[] sk = kdf.derive(hmac.macSize());
         final HashMap map = new HashMap();
         map.put(IMac.MAC_KEY_MATERIAL, sk);
         hmac.init(map);
//System.out.println("**** Initialised IALG with: "+gnu.crypto.util.Util.dumpString(sk));
 	   } catch (InvalidKeyException x) {
          throw new SaslException("getInstance()", x);
 	   }
   }

   public void update(final byte[] data) {
      hmac.update(data, 0, data.length);
   }

   public void update(final byte[] data, final int offset, final int length) {
      hmac.update(data, offset, length);
   }

	public byte[] doFinal() {
		return hmac.digest();
	}

   /**
    * <p>Returns the length (in bytes) of this SASL SRP Integrity Algorithm.</p>
    *
    * @return the length, in bytes, of this integrity protection algorithm.
    */
   public int length() {
      return hmac.macSize();
   }
}