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DES1KeySecretKeyGeneratorImpl |
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1 /* $RCSfile: DES1KeySecretKeyGeneratorImpl.java,v $
2 * $Revision: 1.2 $
3 * $Date: 2002/11/23 11:09:56 $
4 * $Author: uwe_guenther $
5 * $State: Exp $
6 *
7 * Created on August 13, 2001 2:51 PM
8 *
9 * Copyright (C) 2001 Uwe Guenther <uwe@cscc.de>
10 *
11 * This file is part of the jhbci JCE-ServiceProvider. The jhbci JCE-
12 * ServiceProvider is a library, written in JavaTM, that should be
13 * used in HBCI banking applications (clients and may be servers),
14 * to do cryptographic operations.
15 *
16 * The jhbci library is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU Lesser General Public
18 * License as published by the Free Software Foundation; either
19 * version 2.1 of the License, or (at your option) any later version.
20 *
21 * The jhbci library is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
24 * Lesser General Public License for more details.
25 *
26 * You should have received a copy of the GNU Lesser General Public
27 * License along with this library; if not, write to the Free Software
28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
29 *
30 */
31
32 package de.cscc.crypto.provider;
33
34 import java.security.InvalidAlgorithmParameterException;
35 import java.security.InvalidKeyException;
36 import java.security.InvalidParameterException;
37 import java.security.SecureRandom;
38 import java.security.spec.AlgorithmParameterSpec;
39
40 import javax.crypto.SecretKey;
41
42 import de.cscc.crypto.provider.spec.DES1KeySpec;
43
44 /**
45 * DES1KeySecretKeyGeneratorImpl Class.
46 *
47 * @author <a href=mailto:uwe@cscc.de>Uwe Günther</a>
48 * @version $Revision: 1.2 $
49 */
50 final class DES1KeySecretKeyGeneratorImpl {
51
52 /** A reference to the secure random object. */
53 private SecureRandom random = new SecureRandom();
54
55 /** Creates new DES1KeySecretKeyGeneratorImpl. */
56 DES1KeySecretKeyGeneratorImpl() {}
57
58 /**
59 * Returns a string representation of the object.
60 *
61 * @return a string representation of the object.
62 */
63 public String toString() {
64 return "[DES1KeySecretKeyGenerator]";
65 }
66
67 /**
68 * Initializes the key generator.
69 *
70 * @param random the source of randomness for this generator
71 */
72 void init(SecureRandom random) {
73 if (random != null) {
74 this.random = random;
75 }
76 }
77
78 /**
79 * Initializes this key generator for a certain keysize, using the given
80 * source of randomness. We support only 56 bit and 64 bit keysize,
81 * which means the refers to the same result.
82 *
83 * @param keysize the keysize. This is an algorithm-specific metric,
84 * specified in number of bits.
85 * @param random the source of randomness for this key generator.
86 * @throws InvalidParameterException if keysize is wrong or not supported.
87 */
88 void init(int keysize, SecureRandom random)
89 throws InvalidParameterException {
90 if ((keysize != 56) && (keysize != 64)) {
91 throw new InvalidParameterException("Requested key size should be "
92 + "56 bit or 64 bit, not " + keysize + " bit.");
93 }
94
95 init(random);
96 }
97
98 /**
99 * Initializes the key generator with the specified parameter
100 * set and a user-provided source of randomness. The JHBCI
101 * key generator implementation don't use any AlgorithmParameterSpec's.
102 * This means if you want to init the KeyGenerator Object with this
103 * method <code>params</code> have to be null or
104 * InvalidAlgorithmParameterException will be thrown.
105 *
106 * @param params the key generation parameters
107 * @param random the source of randomness for this key generator.
108 * @throws InvalidAlgorithmParameterException if <code>params</code> is
109 * inappropriate for this key generator. We only support <code>null</code>
110 * as parameter for <code>params</code>.
111 */
112 void init(AlgorithmParameterSpec params, SecureRandom random)
113 throws InvalidAlgorithmParameterException {
114 if (params != null) {
115 throw new InvalidAlgorithmParameterException("This KeyGenerator "
116 + "does not support or use any AlgorithmParameterSpec."
117 + "Set parameter AlgorithmParameterSpec params to null, "
118 + "or use init(SecureRandom random) instead.");
119 }
120
121 init(random);
122 }
123
124 /**
125 * Generates a secret key. This method can re-used more than once
126 * for the KeyGenerator Object to generate a lot of SecretKey's.
127 *
128 * @return the new key.
129 */
130 SecretKey generateKey() {
131 //Get memory for the random value.
132 byte[] generatedKeyBytes = new byte[8];
133
134 //Initialize the KeySpec.
135 DES1KeySpec generatedKeySpec = null;
136
137 for (boolean reloop = true; reloop == true;) {
138 //Generate 8 random bytes.
139 this.random.nextBytes(generatedKeyBytes);
140 try{
141 //Put the 8 random bytes in the KeySpec and check if they
142 //are weak or semi weak.
143 generatedKeySpec = new DES1KeySpec(generatedKeyBytes);
144 //If no exception was thrown, we break out of the loop;
145 reloop = false;
146 } catch (InvalidKeyException e) {
147 //If an InvalidKeyException was thrown (means the key
148 //was weak or semi weak), we loop again.
149 reloop = true;
150 }
151 }
152
153 //Put the KeySpec in a new DES1KeySecretKeyImpl and return the
154 //new DES1KeySecretKeyImpl upcasted to SecretKey.
155 return new DES1KeySecretKeyImpl(generatedKeySpec);
156 }
157 }
158
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DES1KeySecretKeyGeneratorImpl |
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