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 /** 48 * Default instance of {@link SHA256KeyHashingScheme}. 49 */ 50 public static final SHA256KeyHashingScheme INSTANCE = new SHA256KeyHashingScheme(); 51 52 private static final Logger LOG = LoggerFactory.getLogger(SHA256KeyHashingScheme.class); 53 54 @Override 55 public String hash(final String key) { 56 final MessageDigest md = getDigest(); 57 md.update(key.getBytes()); 58 return Hex.encodeHexString(md.digest()); 59 } 60 61 private MessageDigest getDigest() { 62 try { 63 return MessageDigest.getInstance("SHA-256"); 64 } catch (final NoSuchAlgorithmException nsae) { 65 LOG.error("can't find SHA-256 implementation for cache key hashing"); 66 throw new MemcachedKeyHashingException(nsae); 67 } 68 } 69 }