dhkeyagreement.java

来自「一个非常好的ssh客户端实现」· Java 代码 · 共 103 行

/******************************************************************************
 *
 * Copyright (c) 1999-2003 AppGate Network Security AB. All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code as
 * defined in and that are subject to the MindTerm Public Source License,
 * Version 2.0, (the 'License'). You may not use this file except in compliance
 * with the License.
 * 
 * You should have received a copy of the MindTerm Public Source License
 * along with this software; see the file LICENSE.  If not, write to
 * AppGate Network Security AB, Otterhallegatan 2, SE-41118 Goteborg, SWEDEN
 *
 *****************************************************************************/

package com.mindbright.security.publickey;

import java.math.BigInteger;

import com.mindbright.jca.security.SecureRandom;
import com.mindbright.jca.security.Key;
import com.mindbright.jca.security.NoSuchAlgorithmException;
import com.mindbright.jca.security.InvalidKeyException;
import com.mindbright.jca.security.InvalidAlgorithmParameterException;
import com.mindbright.jca.security.spec.AlgorithmParameterSpec;

import com.mindbright.jce.crypto.KeyAgreementSpi;
import com.mindbright.jce.crypto.SecretKey;
import com.mindbright.jce.crypto.ShortBufferException;

public final class DHKeyAgreement extends KeyAgreementSpi {

    private DHPrivateKey prvKey;
    private SecureRandom random;
    private BigInteger   lastKey;
    private boolean      lastPhase;

    protected void engineInit(Key key, SecureRandom random)
	throws InvalidKeyException
    {
	if(!(key instanceof DHPrivateKey)) {
	    throw new InvalidKeyException("DHKeyAgreement got: " + key);
	}
	this.prvKey  = (DHPrivateKey)key;
	this.random  = random;
    }

    protected void engineInit(Key key, AlgorithmParameterSpec params,
			      SecureRandom random)
	throws InvalidKeyException, InvalidAlgorithmParameterException
    {
	throw new InvalidAlgorithmParameterException(
				     "DHKeyAgreement params not supported: " +
				     params);
    }

    protected Key engineDoPhase(Key key, boolean lastPhase)
	throws InvalidKeyException, IllegalStateException
    {
	if(!(key instanceof DHPublicKey)) {
	    throw new InvalidKeyException("Invalid key: " + key);
	}
	this.lastPhase = lastPhase;

	BigInteger y  = ((DHPublicKey)key).getY();

	lastKey = DiffieHellman.computeKey(prvKey.getX(),
					   y, prvKey.getP());

	return new DHPublicKey(lastKey, prvKey.getP(), prvKey.getG());
    }

    protected byte[] engineGenerateSecret() throws IllegalStateException {
	if(!lastPhase) {
	    throw new IllegalStateException("DHKeyAgreement not final");
	}
	byte[] sharedSecret = lastKey.toByteArray();
	lastPhase = false;
	lastKey   = null;
	return sharedSecret;
    }

    protected int engineGenerateSecret(byte[] sharedSecret, int offset)
	throws IllegalStateException, ShortBufferException
    {
	byte[] genSecret = engineGenerateSecret();
	if(genSecret.length > (sharedSecret.length - offset)) {
	    throw new ShortBufferException("DHKeyAgreement, buffer too small");
	}
	System.arraycopy(genSecret, 0, sharedSecret, offset, genSecret.length);
	return genSecret.length;
    }

    protected SecretKey engineGenerateSecret(String algorithm)
	throws IllegalStateException, NoSuchAlgorithmException,
	       InvalidKeyException
    {
	throw new Error("DHKeyAgreement.engineGenerateSecret(String) not " +
			"implemented");
    }

}