| /* |
| * Copyright 2005 The Apache Software Foundation. |
| * |
| * Licensed 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. |
| * |
| */ |
| /* |
| * Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
| */ |
| /* |
| * $Id$ |
| */ |
| package javax.xml.crypto; |
| |
| import java.security.Key; |
| import javax.xml.crypto.dsig.keyinfo.KeyInfo; |
| import javax.xml.crypto.dsig.keyinfo.RetrievalMethod; |
| |
| /** |
| * A selector that finds and returns a key using the data contained in a |
| * {@link KeyInfo} object. An example of an implementation of |
| * this class is one that searchs a {@link java.security.KeyStore} for |
| * trusted keys that match information contained in a <code>KeyInfo</code>. |
| * |
| * <p>Whether or not the returned key is trusted and the mechanisms |
| * used to determine that is implementation-specific. |
| * |
| * @author Sean Mullan |
| * @author JSR 105 Expert Group |
| */ |
| public abstract class KeySelector { |
| |
| /** |
| * The purpose of the key that is to be selected. |
| */ |
| public static class Purpose { |
| |
| private final String name; |
| |
| private Purpose(String name) { this.name = name; } |
| |
| /** |
| * Returns a string representation of this purpose ("sign", |
| * "verify", "encrypt", or "decrypt"). |
| * |
| * @return a string representation of this purpose |
| */ |
| public String toString() { return name; } |
| |
| /** |
| * A key for signing. |
| */ |
| public static final Purpose SIGN = new Purpose("sign"); |
| /** |
| * A key for verifying. |
| */ |
| public static final Purpose VERIFY = new Purpose("verify"); |
| /** |
| * A key for encrypting. |
| */ |
| public static final Purpose ENCRYPT = new Purpose("encrypt"); |
| /** |
| * A key for decrypting. |
| */ |
| public static final Purpose DECRYPT = new Purpose("decrypt"); |
| } |
| |
| /** |
| * Default no-args constructor; intended for invocation by subclasses only. |
| */ |
| protected KeySelector() {} |
| |
| /** |
| * Attempts to find a key that satisfies the specified constraints. |
| * |
| * @param keyInfo a <code>KeyInfo</code> (may be <code>null</code>) |
| * @param purpose the key's purpose ({@link Purpose#SIGN}, |
| * {@link Purpose#VERIFY}, {@link Purpose#ENCRYPT}, or |
| * {@link Purpose#DECRYPT}) |
| * @param method the algorithm method that this key is to be used for. |
| * Only keys that are compatible with the algorithm and meet the |
| * constraints of the specified algorithm should be returned. |
| * @param context an <code>XMLCryptoContext</code> that may contain |
| * useful information for finding an appropriate key. If this key |
| * selector supports resolving {@link RetrievalMethod} types, the |
| * context's <code>baseURI</code> and <code>dereferencer</code> |
| * parameters (if specified) should be used by the selector to |
| * resolve and dereference the URI. |
| * @return the result of the key selector |
| * @throws KeySelectorException if an exceptional condition occurs while |
| * attempting to find a key. Note that an inability to find a key is not |
| * considered an exception (<code>null</code> should be |
| * returned in that case). However, an error condition (ex: network |
| * communications failure) that prevented the <code>KeySelector</code> |
| * from finding a potential key should be considered an exception. |
| * @throws ClassCastException if the data type of <code>method</code> |
| * is not supported by this key selector |
| */ |
| public abstract KeySelectorResult select(KeyInfo keyInfo, Purpose purpose, |
| AlgorithmMethod method, XMLCryptoContext context) |
| throws KeySelectorException; |
| |
| /** |
| * Returns a <code>KeySelector</code> that always selects the specified |
| * key, regardless of the <code>KeyInfo</code> passed to it. |
| * |
| * @param key the sole key to be stored in the key selector |
| * @return a key selector that always selects the specified key |
| * @throws NullPointerException if <code>key</code> is <code>null</code> |
| */ |
| public static KeySelector singletonKeySelector(Key key) { |
| return new SingletonKeySelector(key); |
| } |
| |
| private static class SingletonKeySelector extends KeySelector { |
| private final Key key; |
| |
| SingletonKeySelector(Key key) { |
| if (key == null) { |
| throw new NullPointerException(); |
| } |
| this.key = key; |
| } |
| |
| public KeySelectorResult select(KeyInfo keyInfo, Purpose purpose, |
| AlgorithmMethod method, XMLCryptoContext context) |
| throws KeySelectorException { |
| |
| return new KeySelectorResult() { |
| public Key getKey() { |
| return key; |
| } |
| }; |
| } |
| } |
| } |