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 package org.apache.any23.util;
19
20 import java.nio.charset.StandardCharsets;
21 import java.security.MessageDigest;
22 import java.security.NoSuchAlgorithmException;
23
24 /**
25 * Mathematical utility functions.
26 *
27 * @author Michele Mostarda (mostarda@fbk.eu)
28 * @author Davide Palmisano (palmisano@fbk.eu)
29 */
30 public class MathUtils {
31
32 private MathUtils() {
33 }
34
35 /**
36 * <p>
37 * Create a MD5 <b>weak hash</b> for a given string.
38 * </p>
39 * <p>
40 * <b>N.B. This method MUST never be used in a sensitive context</b>. Examples of such usage include (i)
41 * User-password storage, (ii) Security token generation (used to confirm e-mail when registering on a website,
42 * reset password, etc...), (iii) To compute some message integrity.
43 * </p>
44 * Current usage is limited to {@link org.apache.any23.rdf.RDFUtils#getBNode(String)} which is fine for the creation
45 * of blank node(s).
46 *
47 * @param s
48 * input string to create an MD5 hash for.
49 *
50 * @return a string representation of a MD5 {@link java.security.MessageDigest}
51 */
52 public static final String md5(String s) {
53 try {
54 MessageDigest md5 = MessageDigest.getInstance("MD5");
55 md5.reset();
56 md5.update(s.getBytes(StandardCharsets.UTF_8));
57 byte[] digest = md5.digest();
58 StringBuffer result = new StringBuffer();
59 for (byte b : digest) {
60 result.append(Integer.toHexString(0xFF & b));
61 }
62 return result.toString();
63 } catch (NoSuchAlgorithmException e) {
64 throw new RuntimeException("Should never happen, MD5 is supported", e);
65 }
66 }
67
68 }