001 /* $RCSfile: DESede2KeySecretKeyGeneratorEngine.java,v $
002 * $Revision: 1.12 $
003 * $Date: 2003/10/04 19:18:38 $
004 * $Author: uwe_guenther $
005 * $State: Exp $
006 *
007 * Created on August 13, 2001 2:51 PM
008 *
009 * Copyright (C) 2001 Uwe Guenther <uwe@cscc.de>
010 *
011 * This file is part of the jhbci JCE-ServiceProvider. The jhbci JCE-
012 * ServiceProvider is a library, written in JavaTM, that should be
013 * used in HBCI banking applications (clients and may be servers),
014 * to do cryptographic operations.
015 *
016 * The jhbci library is free software; you can redistribute it and/or
017 * modify it under the terms of the GNU Lesser General Public
018 * License as published by the Free Software Foundation; either
019 * version 2.1 of the License, or (at your option) any later version.
020 *
021 * The jhbci library is distributed in the hope that it will be useful,
022 * but WITHOUT ANY WARRANTY; without even the implied warranty of
023 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
024 * Lesser General Public License for more details.
025 *
026 * You should have received a copy of the GNU Lesser General Public
027 * License along with this library; if not, write to the Free Software
028 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
029 *
030 */
031
032 package de.cscc.crypto.provider;
033
034 import java.security.InvalidAlgorithmParameterException;
035 import java.security.InvalidParameterException;
036 import java.security.SecureRandom;
037 import java.security.spec.AlgorithmParameterSpec;
038
039 import javax.crypto.KeyGeneratorSpi;
040 import javax.crypto.SecretKey;
041
042 /**
043 * DESede2KeySecretKeyGeneratorEngine Class provides the functionality
044 * of a DESede key generator for two keys (means 112 or 128 bit key length).
045 * This key generator generates only keys for the "DESede2Key" algorithm in
046 * the JHBCI crypto provider.
047 *
048 * This KeyGenerator Object is re-useable, i.e., after a key has been generated,
049 * the same KeyGenerator Object can be re-used to generate further keys.
050 *
051 * <pre>
052 *
053 * Use the DESede2KeySecretKeyGeneratorEngine through the JCE in the following
054 * way:
055 *
056 * import javax.crypto.KeyGenerator;
057 * import javax.crypto.SecretKey;
058 * import java.security.SecureRandom;
059 *
060 * KeyGenerator kg = new KeyGenerator.getInstance("DESede2Key", "JHBCI");
061 * kg.init(new SecureRandom());
062 * SecretKey key = kg.generateKey();
063 *
064 * //Use key further in a DESede2Key Cipher from the JHBCI provider.
065 * //Or do some other useful things with this nicely generated SecretKey.
066 *
067 * </pre>
068 *
069 *
070 * In this case you does not explicitly initialize the KeyGenerator Object
071 * (in our example code that means <code>kg.init(new SecureRandom());</code>)
072 * we initialize the KeyGenerator Object with <code>new SecureRandom()</code>.
073 * So you can omit the line <code>kg.init(new SecureRandom());</code>.
074 * With this code we will get a SecureRandom implementation of the
075 * higest-priority installed provider. If no one of the installed
076 * providers supply an implementation of SecureRandom, a system provided
077 * source of randomness will be used.
078 * <pre>
079 *
080 * See the changed example:
081 *
082 * import javax.crypto.KeyGenerator;
083 * import javax.crypto.SecretKey;
084 * import java.security.SecureRandom;
085 *
086 * KeyGenerator kg = new KeyGenerator.getInstance("DESede2Key", "JHBCI");
087 * SecretKey key = kg.generateKey();
088 *
089 * //Use key further in a DESede2Key Cipher from the JHBCI provider.
090 * //Or do some other useful things with this nicely generated SecretKey.
091 *
092 * </PRE>
093 * @author <a href=mailto:uwe@cscc.de>Uwe Günther</a>
094 * @version $Revision: 1.12 $
095 */
096 public final class DESede2KeySecretKeyGeneratorEngine extends KeyGeneratorSpi {
097
098 /** The delegate for this wrapper object */
099 private DESede2KeySecretKeyGeneratorImpl generator =
100 new DESede2KeySecretKeyGeneratorImpl();
101
102 /**
103 * Creates new DESede2KeySecretKeyGeneratorEngine.
104 * Mostly used of the static function
105 * <code>KeyGenerator.getInstance(...)</code>.
106 *
107 * @throws SecurityException if the provider self integrity check fails.
108 */
109 public DESede2KeySecretKeyGeneratorEngine() {
110 if (JHBCI.selfIntegrityChecking() == false) {
111 throw new SecurityException("JHBCI-Provider is tampered.");
112 }
113 }
114
115 /**
116 * Returns a string representation of the object.
117 *
118 * @return a string representation of the object.
119 */
120 public String toString() {
121 return this.generator.toString();
122 }
123
124 /**
125 * Initializes the key generator.
126 *
127 * @param random the source of randomness for this generator.
128 */
129 protected void engineInit(SecureRandom random) {
130 this.generator.init(random);
131 }
132
133 /**
134 * Initializes this key generator for a certain keysize, using the given
135 * source of randomness. We support only 112 bit and 128 bit keysize,
136 * which means the refers to the same result.
137 *
138 * @param keysize the keysize. This is an algorithm-specific metric,
139 * specified in number of bits.
140 * @param random the source of randomness for this key generator.
141 * @throws InvalidParameterException if keysize is wrong or not supported.
142 */
143 protected void engineInit(int keysize, SecureRandom random)
144 throws InvalidParameterException {
145 this.generator.init(keysize, random);
146 }
147
148 /**
149 * Initializes the key generator with the specified parameter
150 * set and a user-provided source of randomness. The JHBCI
151 * key generator implementation don't use any AlgorithmParameterSpec's.
152 * This means if you want to init the KeyGenerator Object with this
153 * method <code>params</code> have to be null or
154 * InvalidAlgorithmParameterException will be thrown.
155 *
156 * @param params the key generation parameters.
157 * @param random the source of randomness for this key generator.
158 * @throws InvalidAlgorithmParameterException if <code>params</code> is
159 * inappropriate for this key generator. We only support <code>null</code>
160 * as parameter for <code>params</code>.
161 */
162 protected void engineInit(AlgorithmParameterSpec params, SecureRandom random)
163 throws InvalidAlgorithmParameterException {
164 this.generator.init(params, random);
165 }
166
167 /**
168 * Generates a secret key. This method can re-used more than once
169 * for the KeyGenerator Object to generate a lot of SecretKey's.
170 *
171 * @return the new key.
172 */
173 protected SecretKey engineGenerateKey() {
174 return this.generator.generateKey();
175 }
176 }