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jDLMS is a library implementing the DLMS/COSEM (IEC 62056) communication standard.

There is a newer version: 1.8.0

/*
 * Copyright 2012-16 Fraunhofer ISE
 *
 * This file is part of jDLMS.
 * For more information visit http://www.openmuc.org
 *
 * jDLMS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * jDLMS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with jDLMS.  If not, see .
 *
 */
package org.openmuc.jdlms.internal.security;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Implementation of the HIGH level authentication using MD5 as described in IEC 62056-62
 */
public class HlsProcessorMd5 implements HlsSecretProcessor {

    @Override
    public byte[] process(byte[] challenge, byte[] authenticationKey, byte[] encryptionKey, byte[] systemTitle,
            int frameCounter) throws IOException, UnsupportedOperationException {

        MessageDigest messageDigest = null;
        try {
            messageDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IOException("Could not process secret. No MD5 algorithm installed", e);
        }

        byte[] input = ByteBuffer.allocate(authenticationKey.length + challenge.length)
                .put(challenge)
                .put(authenticationKey)
                .array();

        return messageDigest.digest(input);
    }

}