org.sakaiproject.user.impl.OneWayHash.java Source code

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Here is the source code for org.sakaiproject.user.impl.OneWayHash.java

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/**********************************************************************************
 * $URL: https://source.sakaiproject.org/svn/kernel/tags/kernel-1.0.12/kernel-impl/src/main/java/org/sakaiproject/user/impl/OneWayHash.java $
 * $Id: OneWayHash.java 51317 2008-08-24 04:38:02Z csev@umich.edu $
 ***********************************************************************************
 *
 * Copyright (c) 2003, 2004, 2005, 2006, 2008 Sakai Foundation
 *
 * Licensed under the Educational Community 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.osedu.org/licenses/ECL-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 org.sakaiproject.user.impl;

import java.io.ByteArrayOutputStream;
import java.io.OutputStream;
import java.security.MessageDigest;

import javax.mail.internet.MimeUtility;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>
 * OneWayHash converts a plain text string into an encoded string.
 * </p>
 */
public class OneWayHash {
    /** Our log (commons). */
    private static Log M_log = LogFactory.getLog(OneWayHash.class);

    /**
     * Encode the clear text into an encoded form.
     * 
     * @param clear
     *        The text to encode.
     * @param truncated
     *        return a value truncated as we used to be before fixing SAK-5922 (works only with MD5 algorithm base64'ed)
     * @return The encoded and base64'ed text.
     */
    public static String encode(String clear, boolean truncated) {
        try {
            // compute the digest using the MD5 algorithm
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] digest = md.digest(clear.getBytes("UTF-8"));

            // encode as base64
            ByteArrayOutputStream bas = new ByteArrayOutputStream(digest.length + digest.length / 3 + 1);
            OutputStream encodedStream = MimeUtility.encode(bas, "base64");
            encodedStream.write(digest);

            // we used to pick up the encoding before it was complete, leaving off the last 4 characters of the encoded value
            String truncatedValue = bas.toString();

            // close the stream to complete the encoding
            encodedStream.close();
            String rv = bas.toString();

            // if we are asking for the truncated value, return that
            if (truncated)
                return truncatedValue;

            return rv;
        } catch (Exception e) {
            M_log.warn("OneWayHash.encode: exception: " + e);
            return null;
        }
    }
}