de.topicmapslab.majortom.server.http.util.MD5Util.java Source code

Introduction

Here is the source code for de.topicmapslab.majortom.server.http.util.MD5Util.java

Source

/*******************************************************************************
 * Copyright 2011 Hannes Niederhausen, Topic Maps Lab
 * 
 * Licensed 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.
 ******************************************************************************/
/**
 * 
 */
package de.topicmapslab.majortom.server.http.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.springframework.security.core.codec.Hex;

/**
 * Util class to create a MD5 checksum of a String.
 * 
 * parts of the code are copied from {@link Hex}
 * 
 * @author Hannes Niederhausen
 *
 */
public class MD5Util {

    private static final char[] HEX = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
            'f' };

    /**
     * Calculates the md5 sum of the given string
     * 
     * @param source the source string used to calculate
     * @return the String representing the MD5 sum
     * @throws NoSuchAlgorithmException  if the MD5 algorithm is not available
     */
    public static final String calculateMD5(String source) {
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            byte[] bytes = digest.digest(source.getBytes());

            final int nBytes = bytes.length;
            char[] result = new char[2 * nBytes];

            int j = 0;
            for (int i = 0; i < nBytes; i++) {
                // Char for top 4 bits
                result[j++] = HEX[(0xF0 & bytes[i]) >>> 4];
                // Bottom 4
                result[j++] = HEX[(0x0F & bytes[i])];
            }

            return new String(result);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("Could not calculate md5", e);
        }
    }
}