1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.eclipse.aether.util;
20
21 import java.nio.charset.StandardCharsets;
22 import java.security.MessageDigest;
23 import java.security.NoSuchAlgorithmException;
24
25 /**
26 * A simple digester utility for Strings. Uses {@link MessageDigest} for requested algorithm. Supports one-pass or
27 * several rounds of updates, and as result emits hex encoded String.
28 *
29 * @since 1.9.0
30 */
31 public final class StringDigestUtil {
32 private final MessageDigest digest;
33
34 /**
35 * Constructs instance with given algorithm.
36 *
37 * @see #sha1()
38 * @see #sha1(String)
39 */
40 public StringDigestUtil(final String alg) {
41 try {
42 this.digest = MessageDigest.getInstance(alg);
43 } catch (NoSuchAlgorithmException e) {
44 throw new IllegalStateException("Not supported digest algorithm: " + alg);
45 }
46 }
47
48 /**
49 * Updates instance with passed in string.
50 */
51 public StringDigestUtil update(String data) {
52 if (data != null && !data.isEmpty()) {
53 digest.update(data.getBytes(StandardCharsets.UTF_8));
54 }
55 return this;
56 }
57
58 /**
59 * Returns the digest of all strings passed via {@link #update(String)} as hex string. There is no state preserved
60 * and due implementation of {@link MessageDigest#digest()}, same applies here: this instance "resets" itself.
61 * Hence, the digest hex encoded string is returned only once.
62 *
63 * @see MessageDigest#digest()
64 */
65 public String digest() {
66 return ChecksumUtils.toHexString(digest.digest());
67 }
68
69 /**
70 * Helper method to create {@link StringDigestUtil} using SHA-1 digest algorithm.
71 */
72 public static StringDigestUtil sha1() {
73 return new StringDigestUtil("SHA-1");
74 }
75
76 /**
77 * Helper method to calculate SHA-1 digest and hex encode it.
78 */
79 public static String sha1(final String string) {
80 return sha1().update(string).digest();
81 }
82 }