J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | /* |
| 26 | * $Id: KeySelector.java,v 1.6 2005/05/10 15:47:42 mullan Exp $ |
| 27 | */ |
| 28 | package javax.xml.crypto; |
| 29 | |
| 30 | import java.security.Key; |
| 31 | import javax.xml.crypto.dsig.keyinfo.KeyInfo; |
| 32 | import javax.xml.crypto.dsig.keyinfo.RetrievalMethod; |
| 33 | |
| 34 | /** |
| 35 | * A selector that finds and returns a key using the data contained in a |
| 36 | * {@link KeyInfo} object. An example of an implementation of |
| 37 | * this class is one that searchs a {@link java.security.KeyStore} for |
| 38 | * trusted keys that match information contained in a <code>KeyInfo</code>. |
| 39 | * |
| 40 | * <p>Whether or not the returned key is trusted and the mechanisms |
| 41 | * used to determine that is implementation-specific. |
| 42 | * |
| 43 | * @author Sean Mullan |
| 44 | * @author JSR 105 Expert Group |
| 45 | * @since 1.6 |
| 46 | */ |
| 47 | public abstract class KeySelector { |
| 48 | |
| 49 | /** |
| 50 | * The purpose of the key that is to be selected. |
| 51 | */ |
| 52 | public static class Purpose { |
| 53 | |
| 54 | private final String name; |
| 55 | |
| 56 | private Purpose(String name) { this.name = name; } |
| 57 | |
| 58 | /** |
| 59 | * Returns a string representation of this purpose ("sign", |
| 60 | * "verify", "encrypt", or "decrypt"). |
| 61 | * |
| 62 | * @return a string representation of this purpose |
| 63 | */ |
| 64 | public String toString() { return name; } |
| 65 | |
| 66 | /** |
| 67 | * A key for signing. |
| 68 | */ |
| 69 | public static final Purpose SIGN = new Purpose("sign"); |
| 70 | /** |
| 71 | * A key for verifying. |
| 72 | */ |
| 73 | public static final Purpose VERIFY = new Purpose("verify"); |
| 74 | /** |
| 75 | * A key for encrypting. |
| 76 | */ |
| 77 | public static final Purpose ENCRYPT = new Purpose("encrypt"); |
| 78 | /** |
| 79 | * A key for decrypting. |
| 80 | */ |
| 81 | public static final Purpose DECRYPT = new Purpose("decrypt"); |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * Default no-args constructor; intended for invocation by subclasses only. |
| 86 | */ |
| 87 | protected KeySelector() {} |
| 88 | |
| 89 | /** |
| 90 | * Attempts to find a key that satisfies the specified constraints. |
| 91 | * |
| 92 | * @param keyInfo a <code>KeyInfo</code> (may be <code>null</code>) |
| 93 | * @param purpose the key's purpose ({@link Purpose#SIGN}, |
| 94 | * {@link Purpose#VERIFY}, {@link Purpose#ENCRYPT}, or |
| 95 | * {@link Purpose#DECRYPT}) |
| 96 | * @param method the algorithm method that this key is to be used for. |
| 97 | * Only keys that are compatible with the algorithm and meet the |
| 98 | * constraints of the specified algorithm should be returned. |
| 99 | * @param context an <code>XMLCryptoContext</code> that may contain |
| 100 | * useful information for finding an appropriate key. If this key |
| 101 | * selector supports resolving {@link RetrievalMethod} types, the |
| 102 | * context's <code>baseURI</code> and <code>dereferencer</code> |
| 103 | * parameters (if specified) should be used by the selector to |
| 104 | * resolve and dereference the URI. |
| 105 | * @return the result of the key selector |
| 106 | * @throws KeySelectorException if an exceptional condition occurs while |
| 107 | * attempting to find a key. Note that an inability to find a key is not |
| 108 | * considered an exception (<code>null</code> should be |
| 109 | * returned in that case). However, an error condition (ex: network |
| 110 | * communications failure) that prevented the <code>KeySelector</code> |
| 111 | * from finding a potential key should be considered an exception. |
| 112 | * @throws ClassCastException if the data type of <code>method</code> |
| 113 | * is not supported by this key selector |
| 114 | */ |
| 115 | public abstract KeySelectorResult select(KeyInfo keyInfo, Purpose purpose, |
| 116 | AlgorithmMethod method, XMLCryptoContext context) |
| 117 | throws KeySelectorException; |
| 118 | |
| 119 | /** |
| 120 | * Returns a <code>KeySelector</code> that always selects the specified |
| 121 | * key, regardless of the <code>KeyInfo</code> passed to it. |
| 122 | * |
| 123 | * @param key the sole key to be stored in the key selector |
| 124 | * @return a key selector that always selects the specified key |
| 125 | * @throws NullPointerException if <code>key</code> is <code>null</code> |
| 126 | */ |
| 127 | public static KeySelector singletonKeySelector(Key key) { |
| 128 | return new SingletonKeySelector(key); |
| 129 | } |
| 130 | |
| 131 | private static class SingletonKeySelector extends KeySelector { |
| 132 | private final Key key; |
| 133 | |
| 134 | SingletonKeySelector(Key key) { |
| 135 | if (key == null) { |
| 136 | throw new NullPointerException(); |
| 137 | } |
| 138 | this.key = key; |
| 139 | } |
| 140 | |
| 141 | public KeySelectorResult select(KeyInfo keyInfo, Purpose purpose, |
| 142 | AlgorithmMethod method, XMLCryptoContext context) |
| 143 | throws KeySelectorException { |
| 144 | |
| 145 | return new KeySelectorResult() { |
| 146 | public Key getKey() { |
| 147 | return key; |
| 148 | } |
| 149 | }; |
| 150 | } |
| 151 | } |
| 152 | } |