package gnu.crypto.key;

// ----------------------------------------------------------------------------
// $Id: IKeyPairCodec.java,v 1.2 2005/10/06 04:24:16 rsdio Exp $
//
// Copyright (C) 2001, 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, 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
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// 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
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// 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 java.security.PrivateKey;
import java.security.PublicKey;

/**
 * <p>The visible methods of an object that knows how to encode and decode
 * cryptographic asymmetric keypairs. Codecs are useful for (a) externalising
 * public and private keys for storage and on-the-wire transmission, as well as
 * (b) re-creating their internal Java representation from external sources.</p>
 *
 * @version $Revision: 1.2 $
 */
public interface IKeyPairCodec {

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

   /** Constant identifying the <i>Raw</i> encoding format. */
   int RAW_FORMAT = Registry.RAW_ENCODING_ID;

   // Method(s)
   // -------------------------------------------------------------------------

   /**
    * <p>Returns the unique identifier (within this library) of the format used
    * to externalise public and private keys.</p>
    *
    * @return the identifier of the format, the object supports.
    */
   int getFormatID();

   /**
    * <p>Encodes an instance of a public key for storage or transmission purposes.</p>
    *
    * @param key the non-null key to encode.
    * @return a byte sequence representing the encoding of the designated key
    * according to the format supported by this codec.
    * @exception IllegalArgumentException if the designated key is not supported
    * by this codec.
    */
   byte[] encodePublicKey(PublicKey key);

   /**
    * <p>Encodes an instance of a private key for storage or transmission purposes.</p>
    *
    * @param key the non-null key to encode.
    * @return a byte sequence representing the encoding of the designated key
    * according to the format supported by this codec.
    * @exception IllegalArgumentException if the designated key is not supported
    * by this codec.
    */
   byte[] encodePrivateKey(PrivateKey key);

   /**
    * <p>Decodes an instance of an external public key into its native Java
    * representation.</p>
    *
    * @param input the source of the externalised key to decode.
    * @return a concrete instance of a public key, reconstructed from the
    * designated input.
    * @exception IllegalArgumentException if the designated input does not
    * contain a known representation of a public key for the format supported by
    * the concrete codec.
    */
   PublicKey decodePublicKey(byte[] input);

   /**
    * <p>Decodes an instance of an external private key into its native Java
    * representation.</p>
    *
    * @param input the source of the externalised key to decode.
    * @return a concrete instance of a private key, reconstructed from the
    * designated input.
    * @exception IllegalArgumentException if the designated input does not
    * contain a known representation of a private key for the format supported
    * by the concrete codec.
    */
   PrivateKey decodePrivateKey(byte[] input);
}
