1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18
19 package org.apache.catalina.util;
20
21
22 /**
23 * Encode an MD5 digest into a String.
24 * <p>
25 * The 128 bit MD5 hash is converted into a 32 character long String.
26 * Each character of the String is the hexadecimal representation of 4 bits
27 * of the digest.
28 *
29 * @author Remy Maucherat
30 * @version $Revision: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
31 */
32
33 public final class MD5Encoder {
34
35
36 // ----------------------------------------------------- Instance Variables
37
38
39 private static final char[] hexadecimal =
40 {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
41 'a', 'b', 'c', 'd', 'e', 'f'};
42
43
44 // --------------------------------------------------------- Public Methods
45
46
47 /**
48 * Encodes the 128 bit (16 bytes) MD5 into a 32 character String.
49 *
50 * @param binaryData Array containing the digest
51 * @return Encoded MD5, or null if encoding failed
52 */
53 public String encode( byte[] binaryData ) {
54
55 if (binaryData.length != 16)
56 return null;
57
58 char[] buffer = new char[32];
59
60 for (int i=0; i<16; i++) {
61 int low = (int) (binaryData[i] & 0x0f);
62 int high = (int) ((binaryData[i] & 0xf0) >> 4);
63 buffer[i*2] = hexadecimal[high];
64 buffer[i*2 + 1] = hexadecimal[low];
65 }
66
67 return new String(buffer);
68
69 }
70
71
72 }
73
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