/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sshd.common.kex;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PublicKey;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;
import javax.crypto.KeyAgreement;
import org.apache.sshd.common.Digest;
import org.apache.sshd.common.cipher.ECCurves;
import org.apache.sshd.common.util.SecurityUtils;
/**
* Elliptic Curve Diffie-Hellman key agreement.
*
* @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
*/
public class ECDH extends AbstractDH {
private ECParameterSpec params;
private ECPoint e;
private byte[] e_array;
private ECPoint f;
private KeyPairGenerator myKpairGen;
private KeyAgreement myKeyAgree;
public ECDH() throws Exception {
myKpairGen = SecurityUtils.getKeyPairGenerator("EC");
myKeyAgree = SecurityUtils.getKeyAgreement("ECDH");
}
@Override
public byte[] getE() throws Exception {
if (e == null) {
myKpairGen.initialize(params);
KeyPair myKpair = myKpairGen.generateKeyPair();
myKeyAgree.init(myKpair.getPrivate());
e = ((ECPublicKey) myKpair.getPublic()).getW();
e_array = ECCurves.encodeECPoint(e, params.getCurve());
}
return e_array;
}
@Override
protected byte[] calculateK() throws Exception {
KeyFactory myKeyFac = SecurityUtils.getKeyFactory("EC");
ECPublicKeySpec keySpec = new ECPublicKeySpec(f, params);
PublicKey yourPubKey = myKeyFac.generatePublic(keySpec);
myKeyAgree.doPhase(yourPubKey, true);
return stripLeadingZeroes(myKeyAgree.generateSecret());
}
public void setCurveParameters(ECParameterSpec params) {
this.params = params;
}
@Override
public void setF(byte[] f) {
this.f = ECCurves.decodeECPoint(f, params.getCurve());
}
@Override
public Digest getHash() throws Exception {
return ECCurves.getDigestForParams(params);
}
}