SshKeyExchangeClient.java

/**
 * Copyright 2003-2016 SSHTOOLS Limited. All Rights Reserved.
 *
 * For product documentation visit https://www.sshtools.com/
 *
 * This file is part of J2SSH Maverick.
 *
 * J2SSH Maverick is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * J2SSH Maverick 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 J2SSH Maverick.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.sshtools.ssh.components;

import java.io.IOException;
import java.math.BigInteger;

import com.sshtools.ssh.SshException;
import com.sshtools.ssh2.TransportProtocol;

/**
 * 
 * <p>
 * Abstract representation of an SSH key exchange.
 * </p>
 * 
 * @author Lee David Painter
 */
public abstract class SshKeyExchangeClient implements SshKeyExchange {

	String hashAlgorithm;

	protected SshKeyExchangeClient(String hashAlgorithm) {
		this.hashAlgorithm = hashAlgorithm;
	}

	/**
	 * The secret value produced during key exchange.
	 */
	protected BigInteger secret;

	/**
	 * The exchange hash produced during key exchange.
	 */
	protected byte[] exchangeHash;

	/**
	 * The server's host key.
	 */
	protected byte[] hostKey;

	/**
	 * The signature generated over the exchange hash
	 */
	protected byte[] signature;

	/**
	 * The transport protocol for sending/receiving messages
	 */
	protected TransportProtocol transport;

	/**
	 * Contruct an uninitialized key exchange
	 */
	public SshKeyExchangeClient() {
	}

	/**
	 * Get the key exchange algorithm name.
	 * 
	 * @return the key exchange algorithm.
	 */
	public abstract String getAlgorithm();

	/**
	 * Get the output of the key exchange
	 * 
	 * @return the exchange hash output.
	 */
	public byte[] getExchangeHash() {
		return exchangeHash;
	}

	/**
	 * Get the host key supplied during key exchange.
	 * 
	 * @return the server's host key
	 */
	public byte[] getHostKey() {
		return hostKey;
	}

	/**
	 * Get the secret value produced during key exchange.
	 * 
	 * @return The secret value producted during key exchange
	 */
	public BigInteger getSecret() {
		return secret;
	}

	/**
	 * Get the signature produced during key exchange.
	 * 
	 * @return the signature produced from the exchange hash.
	 */
	public byte[] getSignature() {
		return signature;
	}

	public String getHashAlgorithm() {
		return hashAlgorithm;
	}

	/**
	 * Initialize the key exchange.
	 * 
	 * @param transport
	 * @throws IOException
	 */
	public void init(TransportProtocol transport, boolean ignoreFirstPacket) {
		this.transport = transport;
	}

	/**
	 * Override to perform the client side key exchange. The implementation
	 * should not return until all messages have been sent.
	 * 
	 * @param clientId
	 * @param serverId
	 * @param clientKexInit
	 * @param serverKexInit
	 * @throws IOException
	 */
	public abstract void performClientExchange(String clientId,
			String serverId, byte[] clientKexInit, byte[] serverKexInit)
			throws SshException;

	public abstract boolean isKeyExchangeMessage(int messageid);

	/**
	 * Reset the key exchange.
	 */
	public void reset() {
		exchangeHash = null;
		hostKey = null;
		signature = null;
		secret = null;
	}
}