001/*
002 * The contents of this file are subject to the terms of the Common Development and
003 * Distribution License (the License). You may not use this file except in compliance with the
004 * License.
005 *
006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
007 * specific language governing permission and limitations under the License.
008 *
009 * When distributing Covered Software, include this CDDL Header Notice in each file and include
010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
011 * Header, with the fields enclosed by brackets [] replaced by your own identifying
012 * information: "Portions copyright [year] [name of copyright owner]".
013 *
014 * Copyright 2016 ForgeRock AS.
015 */
016
017package org.forgerock.json.jose.jwe.handlers.encryption;
018
019import java.security.Key;
020
021import org.forgerock.json.jose.exceptions.JweDecryptionException;
022import org.forgerock.json.jose.jwe.EncryptionMethod;
023import org.forgerock.json.jose.jwe.JweEncryption;
024import org.forgerock.util.annotations.VisibleForTesting;
025
026/**
027 * Supports direct encryption using a shared symmetric key.
028 */
029public final class DirectEncryptionHandler implements EncryptionHandler {
030    private final ContentEncryptionHandler contentEncryptionHandler;
031
032    /**
033     * Constructs the direct encryption handler for the given content encryption method.
034     *
035     * @param encryptionMethod the content encryption method.
036     */
037    public DirectEncryptionHandler(final EncryptionMethod encryptionMethod) {
038        this(ContentEncryptionHandler.getInstance(encryptionMethod));
039    }
040
041    @VisibleForTesting
042    DirectEncryptionHandler(ContentEncryptionHandler contentEncryptionHandler) {
043        this.contentEncryptionHandler = contentEncryptionHandler;
044    }
045
046    @Override
047    public Key getContentEncryptionKey() {
048        return null;
049    }
050
051    @Override
052    public byte[] generateJWEEncryptedKey(final Key key, final Key contentEncryptionKey) {
053        // As per https://tools.ietf.org/html/rfc7518#section-4.5 an empty octet sequence is used as the JWE
054        // Encrypted Key value when using direct encryption.
055        return new byte[0];
056    }
057
058    @Override
059    public byte[] generateInitialisationVector() {
060        return contentEncryptionHandler.generateInitialisationVector();
061    }
062
063    @Override
064    public JweEncryption encryptPlaintext(final Key contentEncryptionKey, final byte[] initialisationVector,
065            final byte[] plaintext, final byte[] additionalAuthenticatedData) {
066        return contentEncryptionHandler.encrypt(contentEncryptionKey, initialisationVector, plaintext,
067                additionalAuthenticatedData);
068    }
069
070    @Override
071    public Key decryptContentEncryptionKey(final Key key, final byte[] encryptedContentEncryptionKey) {
072        if (encryptedContentEncryptionKey != null && encryptedContentEncryptionKey.length != 0) {
073            throw new JweDecryptionException();
074        }
075        return key;
076    }
077
078    @Override
079    public byte[] decryptCiphertext(final Key contentEncryptionKey, final byte[] initialisationVector,
080            final byte[] ciphertext,
081            final byte[] authenticationTag, final byte[] additionalAuthenticatedData) {
082        return contentEncryptionHandler.decrypt(contentEncryptionKey, initialisationVector,
083                new JweEncryption(ciphertext, authenticationTag), additionalAuthenticatedData);
084    }
085}