hbase-common/src/main/java/org/apache/hadoop/hbase/util/MD5Hash.java

   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.yetus.audience.InterfaceAudience;
  27 import org.slf4j.Logger;
  28 import org.slf4j.LoggerFactory;
  29
  30 /**
  31  * Utility class for MD5
  32  * MD5 hash produces a 128-bit digest.
  33  */
  34 @InterfaceAudience.Public
  35 public class MD5Hash {
  36   private static final Logger LOG = LoggerFactory.getLogger(MD5Hash.class);
  37
  38   /**
  39    * Given a byte array, returns in MD5 hash as a hex string.
  40    * @param key
  41    * @return SHA1 hash as a 32 character hex string.
  42    */
  43   public static String getMD5AsHex(byte[] key) {
  44     return getMD5AsHex(key, 0, key.length);
  45   }
  46
  47   /**
  48    * Given a byte array, returns its MD5 hash as a hex string.
  49    * Only "length" number of bytes starting at "offset" within the
  50    * byte array are used.
  51    *
  52    * @param key the key to hash (variable length byte array)
  53    * @param offset
  54    * @param length
  55    * @return MD5 hash as a 32 character hex string.
  56    */
  57   public static String getMD5AsHex(byte[] key, int offset, int length) {
  58     try {
  59       MessageDigest md = MessageDigest.getInstance("MD5");
  60       md.update(key, offset, length);
  61       byte[] digest = md.digest();
  62       return new String(Hex.encodeHex(digest));
  63     } catch (NoSuchAlgorithmException e) {
  64       // this should never happen unless the JDK is messed up.
  65       throw new RuntimeException("Error computing MD5 hash", e);
  66     }
  67   }
  68 }