001/*
002 * nimbus-jose-jwt
003 *
004 * Copyright 2012-2016, Connect2id Ltd.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.jose.proc;
019
020
021import java.security.Key;
022import java.util.List;
023
024import com.nimbusds.jose.JWEHeader;
025import com.nimbusds.jose.KeySourceException;
026
027
028/**
029 * Interface for selecting key candidates for decrypting a JSON Web Encryption
030 * (JWE) object. Applications should utilise this interface or a similar
031 * framework to determine whether a received JWE object (or encrypted JWT) is
032 * eligible for {@link com.nimbusds.jose.JWEDecrypter decryption} and further 
033 * processing.
034 *
035 * <p>The interface supports keys selection based on:
036 *
037 * <ul>
038 *     <li>Recognised header parameters referencing the key (e.g. {@code kid},
039 *         {@code x5t}).
040 *     <li>Additional {@link SecurityContext}, if required and set by the
041 *         application (e.g. endpoint where the JWE object was received).
042 * </ul>
043 *
044 * <p>See JSON Web Signature (JWE), Appendix D. Notes on Key Selection for
045 * suggestions.
046 *
047 * <p>Possible key types:
048 *
049 * <ul>
050 *     <li>{@link javax.crypto.SecretKey} for AES keys.
051 *     <li>{@link java.security.interfaces.RSAPrivateKey} private RSA keys.
052 *     <li>{@link java.security.interfaces.ECPrivateKey} private EC keys.
053 * </ul>
054 *
055 * @author Vladimir Dzhuvinov
056 * @version 2016-06-21
057 */
058public interface JWEKeySelector <C extends SecurityContext> {
059
060
061        /**
062         * Selects key candidates for decrypting a JWE object.
063         *
064         * @param header  The header of the JWE object. Must not be
065         *                {@code null}.
066         * @param context Optional context of the JWE object, {@code null} if
067         *                not required.
068         *
069         * @return The key candidates in trial order, empty list if none.
070         *
071         * @throws KeySourceException If a key source exception is encountered,
072         *                            e.g. on remote JWK retrieval.
073         */
074        List<? extends Key> selectJWEKeys(final JWEHeader header, final C context)
075                throws KeySourceException;
076}