package gnu.crypto.key;

// ----------------------------------------------------------------------------
// $Id: IKeyAgreementParty.java,v 1.2 2005/10/06 04:24:16 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 java.util.Map;

/**
 * <p>The visible methods of an key agreement protocol participating party.</p>
 *
 * @version $Revision: 1.2 $
 */
public interface IKeyAgreementParty {

   // Constants
   // -------------------------------------------------------------------------

   // Methods
   // -------------------------------------------------------------------------

   /**
    * <p>Returns the canonical name of the key agreement protocol.</p>
    *
    * @return the canonical name of the key agreement protocol.
    */
   String name();

   /**
    * <p>Sets up the instance to operate with specific attributes.</p>
    *
    * @param attributes a map of name-values used by concrete implementations.
    * @throws KeyAgreementException if an exception occurs during the setup.
    */
   void init(Map attributes) throws KeyAgreementException;

   /**
    * <p>Processes an incoming message at one end, generating a message that
    * will be processed by the other party(ies).</p>
    *
    * @param in the incoming message.
    * @return an outgoing message, or <code>null</code> if this is an
    * intermediary step that does not cause any output.
    * @throws KeyAgreementException if an exception occurs during the processing
    * of the incoming message, or during the generation of the outgoing message.
    */
   OutgoingMessage processMessage(IncomingMessage in) throws KeyAgreementException;

   /**
    * <p>Returns <code>true</code> if the party in the key agreement protocol
    * exchange has completed its part of the exchange. If this is the case an
    * {@link IllegalStateException} is thrown for any method invocation except
    * <code>init()</code> or <code>reset()</code>.
    * @return <code>true</code> if this party has completed its part of the key
    * agreement protocol exchange; <code>false</code> otherwise.
    */
   boolean isComplete();

   /**
    * <p>Returns the byte array containing the shared secret as generated by
    * this party.</p>
    *
    * @return the generated shared secret.
    * @throws KeyAgreementException if the key agreement is not yet initialised,
    * or is initialised but the exchange is still in progress.
    */
   byte[] getSharedSecret() throws KeyAgreementException;

   /** Resets this instance for re-use with another set of attributes. */
   void reset();
}