1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.common.text;
25
26 import java.security.NoSuchAlgorithmException;
27 import org.modeshape.common.util.Base64;
28 import org.modeshape.common.util.CheckArg;
29 import org.modeshape.common.util.SecureHash;
30 import org.modeshape.common.util.SecureHash.Algorithm;
31
32 /**
33 * A text encoder that performs a secure hash of the input text and returns that hash as the encoded text. This encoder can be
34 * configured to use different secure hash algorithms and to return a fixed number of characters from the hash.
35 */
36 public class SecureHashTextEncoder implements TextEncoder {
37
38 private final Algorithm algorithm;
39 private final int maxLength;
40
41 /**
42 * Create an encoder that uses the supplied algorithm and returns only the supplied number of characters in the hash.
43 *
44 * @param algorithm the algorithm that should be used
45 * @throws IllegalArgumentException if the algorithm is null
46 */
47 public SecureHashTextEncoder( Algorithm algorithm ) {
48 this(algorithm, Integer.MAX_VALUE);
49 }
50
51 /**
52 * Create an encoder that uses the supplied algorithm and returns only the supplied number of characters in the hash.
53 *
54 * @param algorithm the algorithm that should be used
55 * @param maxLength the maximumLength, or a non-positive number (or {@link Integer#MAX_VALUE}) if the full hash should be used
56 * @throws IllegalArgumentException if the algorithm is null
57 */
58 public SecureHashTextEncoder( Algorithm algorithm,
59 int maxLength ) {
60 CheckArg.isNotNull(algorithm, "algorithm");
61 this.algorithm = algorithm;
62 this.maxLength = maxLength < 1 ? Integer.MAX_VALUE : maxLength;
63 }
64
65 /**
66 * Get the maximum length of the encoded string, or {@link Integer#MAX_VALUE} if there is no maximum.
67 *
68 * @return the maximum encoded string length; always positive
69 */
70 public int getMaxLength() {
71 return maxLength;
72 }
73
74 /**
75 * Return the secure hash algorithm used by this encoder.
76 *
77 * @return the algorithm; never null
78 */
79 public Algorithm getAlgorithm() {
80 return algorithm;
81 }
82
83 /**
84 * {@inheritDoc}
85 *
86 * @see org.modeshape.common.text.TextEncoder#encode(java.lang.String)
87 */
88 public String encode( String text ) {
89 try {
90 byte[] hash = SecureHash.getHash(algorithm, text.getBytes());
91 String result = Base64.encodeBytes(hash);
92 return result.length() < maxLength ? result : result.substring(0, maxLength);
93 } catch (NoSuchAlgorithmException e) {
94 return text;
95 }
96 }
97
98 }