Java tutorial
//package com.java2s; /* * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. * */ import java.security.MessageDigest; import javax.crypto.Mac; import javax.crypto.spec.SecretKeySpec; public class Main { public static byte[] generateCramMD5HexClientResponse(String userName, String userPassword, byte[] challengeBytes) throws Exception { String macAlgorithm = "HmacMD5"; byte[] digestedPasswordBytes = MessageDigest.getInstance("MD5").digest(userPassword.getBytes("UTF-8")); byte[] hexEncodedDigestedPasswordBytes = toHex(digestedPasswordBytes).getBytes("UTF-8"); Mac mac = Mac.getInstance(macAlgorithm); mac.init(new SecretKeySpec(hexEncodedDigestedPasswordBytes, macAlgorithm)); final byte[] messageAuthenticationCode = mac.doFinal(challengeBytes); String responseAsString = userName + " " + toHex(messageAuthenticationCode); return responseAsString.getBytes(); } public static String toHex(byte[] data) { StringBuffer hash = new StringBuffer(); for (int i = 0; i < data.length; i++) { String hex = Integer.toHexString(0xFF & data[i]); if (hex.length() == 1) { hash.append('0'); } hash.append(hex); } return hash.toString(); } }