Java example source code file (ECDHCrypt.java)

This example Java source code file (ECDHCrypt.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

could, crypto, ecdhcrypt, ecgenparameterspec, ecpoint, ecpublickeyspec, generalsecurityexception, keyagreement, keypair, keypairgenerator, privatekey, publickey, runtimeexception, secretkey, securerandom, security

The ECDHCrypt.java Java example source code

/*
 * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.security.ssl;

import java.security.*;
import java.security.interfaces.ECPublicKey;
import java.security.spec.*;

import javax.crypto.SecretKey;
import javax.crypto.KeyAgreement;

/**
 * Helper class for the ECDH key exchange. It generates the appropriate
 * ephemeral keys as necessary and performs the actual shared secret derivation.
 *
 * @since   1.6
 * @author  Andreas Sterbenz
 */
final class ECDHCrypt {

    // our private key
    private PrivateKey privateKey;

    // our public key
    private ECPublicKey publicKey;

    // Called by ServerHandshaker for static ECDH
    ECDHCrypt(PrivateKey privateKey, PublicKey publicKey) {
        this.privateKey = privateKey;
        this.publicKey = (ECPublicKey)publicKey;
    }

    // Called by ServerHandshaker for ephemeral ECDH
    ECDHCrypt(String curveName, SecureRandom random) {
        try {
            KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("EC");
            ECGenParameterSpec params = new ECGenParameterSpec(curveName);
            kpg.initialize(params, random);
            KeyPair kp = kpg.generateKeyPair();
            privateKey = kp.getPrivate();
            publicKey = (ECPublicKey)kp.getPublic();
        } catch (GeneralSecurityException e) {
            throw new RuntimeException("Could not generate DH keypair", e);
        }
    }

    // Called by ClientHandshaker with params it received from the server
    ECDHCrypt(ECParameterSpec params, SecureRandom random) {
        try {
            KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("EC");
            kpg.initialize(params, random);
            KeyPair kp = kpg.generateKeyPair();
            privateKey = kp.getPrivate();
            publicKey = (ECPublicKey)kp.getPublic();
        } catch (GeneralSecurityException e) {
            throw new RuntimeException("Could not generate DH keypair", e);
        }
    }

    /**
     * Gets the public key of this end of the key exchange.
     */
    PublicKey getPublicKey() {
        return publicKey;
    }

    // called by ClientHandshaker with either the server's static or ephemeral public key
    SecretKey getAgreedSecret(PublicKey peerPublicKey) {
        try {
            KeyAgreement ka = JsseJce.getKeyAgreement("ECDH");
            ka.init(privateKey);
            ka.doPhase(peerPublicKey, true);
            return ka.generateSecret("TlsPremasterSecret");
        } catch (GeneralSecurityException e) {
            throw new RuntimeException("Could not generate secret", e);
        }
    }

    // called by ServerHandshaker
    SecretKey getAgreedSecret(byte[] encodedPoint) {
        try {
            ECParameterSpec params = publicKey.getParams();
            ECPoint point = JsseJce.decodePoint(encodedPoint, params.getCurve());
            KeyFactory kf = JsseJce.getKeyFactory("EC");
            ECPublicKeySpec spec = new ECPublicKeySpec(point, params);
            PublicKey peerPublicKey = kf.generatePublic(spec);
            return getAgreedSecret(peerPublicKey);
        } catch (GeneralSecurityException e) {
            throw new RuntimeException("Could not generate secret", e);
        } catch (java.io.IOException e) {
            throw new RuntimeException("Could not generate secret", e);
        }
    }

}