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, software 14 * distributed under the License is distributed on an "AS IS" BASIS, 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 package org.apache.hadoop.hbase.util; 21 22 import java.security.MessageDigest; 23 import java.security.NoSuchAlgorithmException; 24 25 import org.apache.commons.codec.binary.Hex; 26 import org.apache.commons.logging.Log; 27 import org.apache.commons.logging.LogFactory; 28 import org.apache.hadoop.hbase.classification.InterfaceAudience; 29 import org.apache.hadoop.hbase.classification.InterfaceStability; 30 31 /** 32 * Utility class for MD5 33 * MD5 hash produces a 128-bit digest. 34 */ 35 @InterfaceAudience.Public 36 @InterfaceStability.Stable 37 public class MD5Hash { 38 private static final Log LOG = LogFactory.getLog(MD5Hash.class); 39 40 /** 41 * Given a byte array, returns in MD5 hash as a hex string. 42 * @param key 43 * @return SHA1 hash as a 32 character hex string. 44 */ 45 public static String getMD5AsHex(byte[] key) { 46 return getMD5AsHex(key, 0, key.length); 47 } 48 49 /** 50 * Given a byte array, returns its MD5 hash as a hex string. 51 * Only "length" number of bytes starting at "offset" within the 52 * byte array are used. 53 * 54 * @param key the key to hash (variable length byte array) 55 * @param offset 56 * @param length 57 * @return MD5 hash as a 32 character hex string. 58 */ 59 public static String getMD5AsHex(byte[] key, int offset, int length) { 60 try { 61 MessageDigest md = MessageDigest.getInstance("MD5"); 62 md.update(key, offset, length); 63 byte[] digest = md.digest(); 64 return new String(Hex.encodeHex(digest)); 65 } catch (NoSuchAlgorithmException e) { 66 // this should never happen unless the JDK is messed up. 67 throw new RuntimeException("Error computing MD5 hash", e); 68 } 69 } 70 }