/*
* Copyright (c) 2010-2011 Michael Laudati, N1 Concepts LLC.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL N1
* CONCEPTS LLC OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.vngx.jsch.kex;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PublicKey;
import javax.crypto.KeyAgreement;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.DHPublicKeySpec;
import org.vngx.jsch.config.JSchConfig;
/**
* Implementation of {@code DiffieHellman} using the implementation provided
* through JCE.
*
* @see org.vngx.jsch.DiffieHellman
*
* @author Michael Laudati
*/
public final class DiffieHellmanImpl implements DiffieHellman {
/** JCE key pair generator. */
private final KeyPairGenerator _keyPairGenerator;
/** JCE key agreement. */
private final KeyAgreement _keyAgreement;
/** Prime number. */
private BigInteger _p;
/** Generator value. */
private BigInteger _g;
/** My public key. */
private BigInteger _e;
/** Byte value of public key e. */
private byte[] _eArray;
/** Public key. */
private BigInteger _f;
/** Shared secret key. */
private BigInteger _K;
/** Byte value of shared secret key. */
private byte[] _KArray;
/**
* Creates a new instance of {@code DiffieHellmanImpl}.
*
* @throws NoSuchAlgorithmException if DH algorithm cannot be found
* @throws NoSuchProviderException if default provider cannot be found
*/
public DiffieHellmanImpl() throws NoSuchAlgorithmException, NoSuchProviderException {
String provider = JSchConfig.getConfig().getString(JSchConfig.DEFAULT_SECURITY_PROVIDER);
if( provider.length()==0 ) {
_keyPairGenerator = KeyPairGenerator.getInstance("DH");
_keyAgreement = KeyAgreement.getInstance("DH");
} else {
_keyPairGenerator = KeyPairGenerator.getInstance("DH", provider);
_keyAgreement = KeyAgreement.getInstance("DH", provider);
}
}
@Override
public byte[] getE() throws Exception {
if( _e == null ) {
_keyPairGenerator.initialize(new DHParameterSpec(_p, _g));
KeyPair myKpair = _keyPairGenerator.generateKeyPair();
_keyAgreement.init(myKpair.getPrivate());
//byte[] myPubKeyEnc = myKpair.getPublic().getEncoded();
_e = ((DHPublicKey) (myKpair.getPublic())).getY();
_eArray = _e.toByteArray();
}
return _eArray;
}
@Override
public byte[] getK() throws Exception {
if( _K == null ) {
KeyFactory myKeyFac = KeyFactory.getInstance("DH");
PublicKey yourPubKey = myKeyFac.generatePublic(new DHPublicKeySpec(_f, _p, _g));
_keyAgreement.doPhase(yourPubKey, true);
byte[] mySharedSecret = _keyAgreement.generateSecret();
_K = new BigInteger(mySharedSecret);
//_KArray = _K.toByteArray(); // TODO Why assign twice?
_KArray = mySharedSecret;
}
return _KArray;
}
@Override
public void setP(byte[] p) {
_p = new BigInteger(p);
}
@Override
public void setG(byte[] g) {
_g = new BigInteger(g);
}
@Override
public void setF(byte[] f) {
_f = new BigInteger(f);
}
}