1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27 package org.apache.hc.client5.http.impl.cache.memcached;
28
29 import java.security.MessageDigest;
30 import java.security.NoSuchAlgorithmException;
31
32 import org.apache.hc.client5.http.utils.Hex;
33 import org.slf4j.Logger;
34 import org.slf4j.LoggerFactory;
35
36 /**
37 * This is a {@link KeyHashingScheme} based on the
38 * <a href="http://en.wikipedia.org/wiki/SHA-2">SHA-256</a>
39 * algorithm. The hashes produced are hex-encoded SHA-256
40 * digests and hence are always 64-character hexadecimal
41 * strings.
42 *
43 * @since 4.1
44 */
45 public final class SHA256KeyHashingScheme implements KeyHashingScheme {
46
47 public static final SHA256KeyHashingScheme INSTANCE = new SHA256KeyHashingScheme();
48
49 private static final Logger LOG = LoggerFactory.getLogger(SHA256KeyHashingScheme.class);
50
51 @Override
52 public String hash(final String key) {
53 final MessageDigest md = getDigest();
54 md.update(key.getBytes());
55 return Hex.encodeHexString(md.digest());
56 }
57
58 private MessageDigest getDigest() {
59 try {
60 return MessageDigest.getInstance("SHA-256");
61 } catch (final NoSuchAlgorithmException nsae) {
62 LOG.error("can't find SHA-256 implementation for cache key hashing");
63 throw new MemcachedKeyHashingException(nsae);
64 }
65 }
66 }