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package gnu.crypto.key.dh;
// ----------------------------------------------------------------------------
// $Id: GnuDHPublicKey.java,v 1.1 2003/09/26 23:50:48 raif 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.,
// 59 Temple Place - Suite 330,
// Boston, MA 02111-1307
// 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.key.IKeyPairCodec;
import java.math.BigInteger;
import javax.crypto.interfaces.DHPublicKey;
/**
* An implementation of the Diffie-Hellman public key.
*
* Reference:
*
* - Diffie-Hellman Key
* Agreement Method
* Eric Rescorla.
*
*
* @version $Revision: 1.1 $
*/
public class GnuDHPublicKey extends GnuDHKey implements DHPublicKey {
// Constants and variables
// -------------------------------------------------------------------------
private BigInteger y;
// Constructor(s)
// -------------------------------------------------------------------------
public GnuDHPublicKey(BigInteger q, BigInteger p, BigInteger g, BigInteger y) {
super(q, p, g);
this.y = y;
}
// Class methods
// -------------------------------------------------------------------------
/**
* A class method that takes the output of the encodePublicKey()
* method of a DH keypair codec object (an instance implementing
* {@link IKeyPairCodec} for DSS keys, and re-constructs an instance of this
* object.
*
* @param k the contents of a previously encoded instance of this object.
* @exception ArrayIndexOutOfBoundsException if there is not enough bytes,
* in k, to represent a valid encoding of an instance of this
* object.
* @exception IllegalArgumentException if the byte sequence does not
* represent a valid encoding of an instance of this object.
*/
public static GnuDHPublicKey valueOf(byte[] k) {
// check magic...
// we should parse here enough bytes to know which codec to use, and
// direct the byte array to the appropriate codec. since we only have one
// codec, we could have immediately tried it; nevertheless since testing
// one byte is cheaper than instatiating a codec that will fail we test
// the first byte before we carry on.
if (k[0] == Registry.MAGIC_RAW_DH_PUBLIC_KEY[0]) {
// it's likely to be in raw format. get a raw codec and hand it over
IKeyPairCodec codec = new DHKeyPairRawCodec();
return (GnuDHPublicKey) codec.decodePublicKey(k);
} else {
throw new IllegalArgumentException("magic");
}
}
// Instance methods
// -------------------------------------------------------------------------
// java.security.Key interface implementation ------------------------------
/** @deprecated see getEncoded(int). */
public byte[] getEncoded() {
return getEncoded(IKeyPairCodec.RAW_FORMAT);
}
// javax.crypto.interfaces.DHPublicKey interface implementation ------------
public BigInteger getY() {
return y;
}
// other methods -----------------------------------------------------------
/**
* Returns the encoded form of this public key according to the designated
* format.
*
* @param format the desired format identifier of the resulting encoding.
* @return the byte sequence encoding this key according to the designated
* format.
* @exception IllegalArgumentException if the format is not supported.
* @see gnu.crypto.key.dh.DHKeyPairRawCodec
*/
public byte[] getEncoded(int format) {
byte[] result;
switch (format) {
case IKeyPairCodec.RAW_FORMAT:
result = new DHKeyPairRawCodec().encodePublicKey(this);
break;
default:
throw new IllegalArgumentException("format");
}
return result;
}
}