package gnu.crypto.key.dss;
// ----------------------------------------------------------------------------
// $Id: DSSPrivateKey.java,v 1.2 2005/10/06 04:24:16 rsdio Exp $
//
// Copyright (C) 2001, 2002, 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
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// independent modules, and to copy and distribute the resulting
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// library, you may extend this exception to your version of the
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// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------
import gnu.crypto.Registry;
import gnu.crypto.key.IKeyPairCodec;
import java.math.BigInteger;
import java.security.PrivateKey;
import java.security.interfaces.DSAPrivateKey;
/**
* <p>An object that embodies a DSS (Digital Signature Standard) private key.</p>
*
* @version $Revision: 1.2 $
* @see #getEncoded
*/
public class DSSPrivateKey extends DSSKey implements PrivateKey, DSAPrivateKey {
// Constants and variables
// -------------------------------------------------------------------------
/**
* <p>A randomly or pseudorandomly generated integer with <code>0 < x <
* q</code>.</p>
*/
private final BigInteger x;
// Constructor(s)
// -------------------------------------------------------------------------
/**
* <p>Trivial constructor.</p>
*
* @param p the public modulus.
* @param q the public prime divisor of <code>p-1</code>.
* @param g a generator of the unique cyclic group <code>Z<sup>*</sup>
* <sub>p</sub></code>.
* @param x the private key part.
*/
public DSSPrivateKey(BigInteger p, BigInteger q, BigInteger g, BigInteger x) {
super(p, q, g);
this.x = x;
}
// Class methods
// -------------------------------------------------------------------------
/**
* <p>A class method that takes the output of the <code>encodePrivateKey()</code>
* method of a DSS keypair codec object (an instance implementing
* {@link gnu.crypto.key.IKeyPairCodec} for DSS keys, and re-constructs an
* instance of this object.</p>
*
* @param k the contents of a previously encoded instance of this object.
* @exception ArrayIndexOutOfBoundsException if there is not enough bytes,
* in <code>k</code>, 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 DSSPrivateKey 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_DSS_PRIVATE_KEY[0]) {
// it's likely to be in raw format. get a raw codec and hand it over
IKeyPairCodec codec = new DSSKeyPairRawCodec();
return (DSSPrivateKey) codec.decodePrivateKey(k);
} else {
throw new IllegalArgumentException("magic");
}
}
// Instance methods
// -------------------------------------------------------------------------
// java.security.interfaces.DSAPrivateKey interface implementation ---------
public BigInteger getX() {
return x;
}
// Other instance methods --------------------------------------------------
/**
* <p>Returns the encoded form of this private key according to the
* designated format.</p>
*
* @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 DSSKeyPairRawCodec
*/
public byte[] getEncoded(int format) {
byte[] result;
switch (format) {
case IKeyPairCodec.RAW_FORMAT:
result = new DSSKeyPairRawCodec().encodePrivateKey(this);
break;
default:
throw new IllegalArgumentException("format");
}
return result;
}
/**
* <p>Returns <code>true</code> if the designated object is an instance of
* {@link DSAPrivateKey} and has the same DSS (Digital Signature Standard)
* parameter values as this one.</p>
*
* @param obj the other non-null DSS key to compare to.
* @return <code>true</code> if the designated object is of the same type and
* value as this one.
*/
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (!(obj instanceof DSAPrivateKey)) {
return false;
}
DSAPrivateKey that = (DSAPrivateKey) obj;
return super.equals(that) && x.equals(that.getX());
}
}