Convert Microsoft GUID to Java UUID

UUIDUtils.java

// Original source: https://github.com/zagyi/adsync4j/blob/master/core/src/main/java/org/adsync4j/impl/UUIDUtils.java

/*******************************************************************************
 * ADSync4J (https://github.com/zagyi/adsync4j)
 *
 * Copyright (c) 2013 Balazs Zagyvai
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Balazs Zagyvai
 ******************************************************************************/
package org.adsync4j.impl;

import java.util.UUID;

/**
 * Utility class dealing with the {@link UUID}s.
 */
public class UUIDUtils {

    /**
     * Converts a byte array into an {@link UUID} object.
     * <p/>
     * Microsoft stores GUIDs in a binary format that differs from the RFC standard of UUIDs (RFC #4122). (See details
     * at http://en.wikipedia.org/wiki/Globally_unique_identifier) This function takes a byte array read from Active
     * Directory and correctly decodes it as a {@link UUID} object.
     *
     * @param bytes Byte array received as en entry attribute from Active Directory.
     * @return {@link UUID} object created from the byte array, or null in case the passed array is not exactly 16 bytes long.
     */
    public static UUID bytesToUUID(byte[] bytes) {
        if (bytes != null && bytes.length == 16) {
            long msb = bytes[3] & 0xFF;
            msb = msb << 8 | (bytes[2] & 0xFF);
            msb = msb << 8 | (bytes[1] & 0xFF);
            msb = msb << 8 | (bytes[0] & 0xFF);

            msb = msb << 8 | (bytes[5] & 0xFF);
            msb = msb << 8 | (bytes[4] & 0xFF);

            msb = msb << 8 | (bytes[7] & 0xFF);
            msb = msb << 8 | (bytes[6] & 0xFF);

            long lsb = bytes[8] & 0xFF;
            lsb = lsb << 8 | (bytes[9] & 0xFF);
            lsb = lsb << 8 | (bytes[10] & 0xFF);
            lsb = lsb << 8 | (bytes[11] & 0xFF);
            lsb = lsb << 8 | (bytes[12] & 0xFF);
            lsb = lsb << 8 | (bytes[13] & 0xFF);
            lsb = lsb << 8 | (bytes[14] & 0xFF);
            lsb = lsb << 8 | (bytes[15] & 0xFF);

            return new UUID(msb, lsb);
        }
        return null;
    }
}

Thanks! This was very helpful.

Here is a version using ByteBuffer if anyone is interested.

// MSB bytes are the first 8 bytes in this order [3,2,1,0,5,4,7,6]
long msb = ByteBuffer.allocate(8)
                     .put(3, bytes[0])
                     .put(2, bytes[1])
                     .put(1, bytes[2])
                     .put(0, bytes[3])
                     .put(5, bytes[4])
                     .put(4, bytes[5])
                     .put(7, bytes[6])
                     .put(6, bytes[7])
                     .getLong();

// LSB are just the last 8 bytes in the same order
long lsb = ByteBuffer.wrap(bytes, 8, 8).getLong();

return new UUID(msb, lsb);

Thanks, robotdan. Glad it was helpful!

This is to read a GUID direct from a buffer

private static UUID getGuid(ByteBuffer buffer) {
        if (buffer.remaining() >= 16) {
            long msb = buffer.get(buffer.position() + 3) & 0xFF;
            msb = msb << 8 | (buffer.get(buffer.position() + 2) & 0xff);
            msb = msb << 8 | (buffer.get(buffer.position() + 1) & 0xff);
            msb = msb << 8 | (buffer.get(buffer.position()) & 0xff);

            msb = msb << 8 | (buffer.get(buffer.position() + 5) & 0xff);
            msb = msb << 8 | (buffer.get(buffer.position() + 4) & 0xff);

            msb = msb << 8 | (buffer.get(buffer.position() + 7) & 0xff);
            msb = msb << 8 | (buffer.get(buffer.position() + 6) & 0xff);

            long lsb = buffer.get(buffer.position() + 8) & 0xff;
            lsb = lsb << 8 | (buffer.get(buffer.position() + 9) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 10) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 11) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 12) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 13) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 14) & 0xff);
            lsb = lsb << 8 | (buffer.get(buffer.position() + 15) & 0xff);

            buffer.position(buffer.position() + 16);
            return new UUID(msb, lsb);
        }

        return null;
    }