1 /** 2 * Copyright 2010 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 21 package org.apache.hadoop.hbase.util; 22 23 import java.security.MessageDigest; 24 import java.security.NoSuchAlgorithmException; 25 26 import org.apache.commons.codec.binary.Hex; 27 import org.apache.commons.logging.Log; 28 import org.apache.commons.logging.LogFactory; 29 30 /** 31 * Utility class for MD5 32 * MD5 hash produces a 128-bit digest. 33 */ 34 public class MD5Hash { 35 private static final Log LOG = LogFactory.getLog(MD5Hash.class); 36 37 /** 38 * Given a byte array, returns in MD5 hash as a hex string. 39 * @param key 40 * @return SHA1 hash as a 32 character hex string. 41 */ 42 public static String getMD5AsHex(byte[] key) { 43 return getMD5AsHex(key, 0, key.length); 44 } 45 46 /** 47 * Given a byte array, returns its MD5 hash as a hex string. 48 * Only "length" number of bytes starting at "offset" within the 49 * byte array are used. 50 * 51 * @param key the key to hash (variable length byte array) 52 * @param offset 53 * @param length 54 * @return MD5 hash as a 32 character hex string. 55 */ 56 public static String getMD5AsHex(byte[] key, int offset, int length) { 57 try { 58 MessageDigest md = MessageDigest.getInstance("MD5"); 59 md.update(key, offset, length); 60 byte[] digest = md.digest(); 61 return new String(Hex.encodeHex(digest)); 62 } catch (NoSuchAlgorithmException e) { 63 // this should never happen unless the JDK is messed up. 64 throw new RuntimeException("Error computing MD5 hash", e); 65 } 66 } 67 }