dhkeypairgenerator.java

面向应用的智能安全代理平台和工具包是一个综合网络应用的安全共性需求而设计和实现的一个通用性的网络信息安全应用支撑平台

package au.net.aba.crypto.provider;

/*
 * $Id: DHKeyPairGenerator.java,v 1.7 1999/02/18 07:04:09 leachbj Exp $
 * $Author: leachbj $
 *
 * Copyright (C) 1996-1998 Australian Business Access Pty Ltd.
 * All rights reserved.
 * 
 * Use, modification, copying and distribution of this software is subject the
 * terms and conditions of the ABA Public Licence. See the file
 * "PUBLIC_LICENCE" for additional information.
 *
 * If you have not received a copy of the Public Licence, you must destroy all
 * copies of this file immediately. 
 *
 * $Source: /aba/CVSROOT/jdk1.1/src/au.net.aba/crypto/provider/DHKeyPairGenerator.java,v $
 * $Revision: 1.7 $
 * $Date: 1999/02/18 07:04:09 $
 * $State: Exp $
 */

import java.security.*;
import java.math.*;

import javax.crypto.spec.*;

import java.security.*;
import java.security.spec.*;

/**
 * a key pair generator for Diffie-Hellman keys (note: incomplete).
 */
public class DHKeyPairGenerator extends KeyPairGenerator
{
	public final static String ident = "$Id: DHKeyPairGenerator.java,v 1.7 1999/02/18 07:04:09 leachbj Exp $";

	private BigInteger y;
	private BigInteger x;
	private BigInteger p;
	private BigInteger g;

	private int primeSize;
	private int exponentSize;

	private SecureRandom random;

	/**
	 * basic constructor
	 */
	public DHKeyPairGenerator()
	{
		super("DH");

		primeSize = 512;
		exponentSize = 504;
	}
	/**
	 * return a new Diffie-Hellman key pair.
	 *
	 * @return a Diffie-Hellman key pair.
	 */
	public KeyPair generateKeyPair()
	{
		KeyPair keyPair = null;
		if (exponentSize == 0)
		{
			exponentSize = primeSize - 1;
		}

		if (p == null || g == null)
		{
			throw new IllegalStateException(
					"generator uninitialised");
		}

		x = new BigInteger(exponentSize, random);
		y = g.modPow(x, p);

		return new KeyPair(
			new DHPubKey(y, p, g, exponentSize),
			new DHPrivKey(x, p, g, exponentSize));
	}
	/**
	 * initialise the key pair generator with the given prime size
	 * and random byte source.
	 *
	 * @param spec		a parameter spec.
	 * @param random	a source of random bytes.
	 * @exception InvalidAlgorithmParameterException if the params argument
	 *	is invalid.
	 */
	public void initialise(
		AlgorithmParameterSpec	spec,
		SecureRandom		random)
		throws InvalidAlgorithmParameterException
	{
		if (!(spec instanceof DHParameterSpec))
		{
			throw new InvalidAlgorithmParameterException(
							"Bad parameter spec");
		}

		this.random = random;

		p = ((DHParameterSpec)spec).getP();
		g = ((DHParameterSpec)spec).getG();

		primeSize = p.bitLength();
		exponentSize = ((DHParameterSpec)spec).getL();

		if (exponentSize != 0 && exponentSize >= primeSize)
		{
			throw new InvalidAlgorithmParameterException(
				"Exponent must be smaller than modulus");
		}
	}
	/**
	 * initialise the key pair generator with the given prime size
	 * and random byte source.
	 *
	 * @param primeSize	prime number size.
	 * @param random	a source of random bytes.
	 */
	public void initialize(
		int		primeSize,
		SecureRandom	random)
	{
		this.primeSize = primeSize;
		exponentSize = 0;
		this.random = random;
	}
}