/* * Copyright (c) 2009, 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.ec; import java.security.*;import java.security.interfaces.*;import java.security.spec.*; import javax.crypto.*;import javax.crypto.spec.*; /** * KeyAgreement implementation for ECDH. * * @since   1.7 */public final class ECDHKeyAgreement extends KeyAgreementSpi {     // private key, if initialized    private ECPrivateKey privateKey;     // encoded public point, non-null between doPhase() & generateSecret() only    private byte[] publicValue;     // length of the secret to be derived    private int secretLen;     /**     * Constructs a new ECDHKeyAgreement.     */    public ECDHKeyAgreement() {    }     // see JCE spec    @Override    protected void engineInit(Key key, SecureRandom random)            throws InvalidKeyException {        if (!(key instanceof PrivateKey)) {            throw new InvalidKeyException                        ("Key must be instance of PrivateKey");        }        privateKey = (ECPrivateKey) ECKeyFactory.toECKey(key);        publicValue = null;    }     // see JCE spec    @Override    protected void engineInit(Key key, AlgorithmParameterSpec params,            SecureRandom random) throws InvalidKeyException,            InvalidAlgorithmParameterException {        if (params != null) {            throw new InvalidAlgorithmParameterException                        ("Parameters not supported");        }        engineInit(key, random);    }     // see JCE spec    @Override    protected Key engineDoPhase(Key key, boolean lastPhase)            throws InvalidKeyException, IllegalStateException {        if (privateKey == null) {            throw new IllegalStateException("Not initialized");        }        if (publicValue != null) {            throw new IllegalStateException("Phase already executed");        }        if (!lastPhase) {            throw new IllegalStateException                ("Only two party agreement supported, lastPhase must be true");        }        if (!(key instanceof ECPublicKey)) {            throw new InvalidKeyException                ("Key must be a PublicKey with algorithm EC");        }         ECPublicKey ecKey = (ECPublicKey)key;        ECParameterSpec params = ecKey.getParams();         if (ecKey instanceof ECPublicKeyImpl) {            publicValue = ((ECPublicKeyImpl)ecKey).getEncodedPublicValue();        } else { // instanceof ECPublicKey            publicValue =                ECParameters.encodePoint(ecKey.getW(), params.getCurve());        }        int keyLenBits = params.getCurve().getField().getFieldSize();        secretLen = (keyLenBits + 7) >> 3;         return null;    }     // see JCE spec    @Override    protected byte[] engineGenerateSecret() throws IllegalStateException {        if ((privateKey == null) || (publicValue == null)) {            throw new IllegalStateException("Not initialized correctly");        }         byte[] s = privateKey.getS().toByteArray();        byte[] encodedParams =            ECParameters.encodeParameters(privateKey.getParams()); // DER OID         try {             return deriveKey(s, publicValue, encodedParams);         } catch (GeneralSecurityException e) {            throw new ProviderException("Could not derive key", e);        }     }     // see JCE spec    @Override    protected int engineGenerateSecret(byte[] sharedSecret, int            offset) throws IllegalStateException, ShortBufferException {        if (offset + secretLen > sharedSecret.length) {            throw new ShortBufferException("Need " + secretLen                + " bytes, only " + (sharedSecret.length - offset) + " available");        }        byte[] secret = engineGenerateSecret();        System.arraycopy(secret, 0, sharedSecret, offset, secret.length);        return secret.length;    }     // see JCE spec    @Override    protected SecretKey engineGenerateSecret(String algorithm)            throws IllegalStateException, NoSuchAlgorithmException,            InvalidKeyException {        if (algorithm == null) {            throw new NoSuchAlgorithmException("Algorithm must not be null");        }        if (!(algorithm.equals("TlsPremasterSecret"))) {            throw new NoSuchAlgorithmException                ("Only supported for algorithm TlsPremasterSecret");        }        return new SecretKeySpec(engineGenerateSecret(), "TlsPremasterSecret");    }     /**     * Generates a secret key using the public and private keys.     *     * @param s the private key's S value.     * @param w the public key's W point (in uncompressed form).     * @param encodedParams the curve's DER encoded object identifier.     *     * @return byte[] the secret key.     */    private static native byte[] deriveKey(byte[] s, byte[] w,        byte[] encodedParams) throws GeneralSecurityException;}