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.http.impl.client.cache.memcached; 28 29 import java.security.MessageDigest; 30 import java.security.NoSuchAlgorithmException; 31 32 import org.apache.commons.codec.binary.Hex; 33 import org.apache.commons.logging.Log; 34 import org.apache.commons.logging.LogFactory; 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 public class SHA256KeyHashingScheme implements KeyHashingScheme { 44 45 private static final Log log = LogFactory.getLog(SHA256KeyHashingScheme.class); 46 47 @Override 48 public String hash(final String key) { 49 final MessageDigest md = getDigest(); 50 md.update(key.getBytes()); 51 return Hex.encodeHexString(md.digest()); 52 } 53 54 private MessageDigest getDigest() { 55 try { 56 return MessageDigest.getInstance("SHA-256"); 57 } catch (final NoSuchAlgorithmException nsae) { 58 log.error("can't find SHA-256 implementation for cache key hashing"); 59 throw new MemcachedKeyHashingException(nsae); 60 } 61 } 62 }