/*
 *  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. 
 *  
 */
package org.apache.directory.server.kerberos.shared.crypto.checksum;


import java.security.GeneralSecurityException;

import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.directory.server.kerberos.shared.crypto.encryption.KeyUsage;
import org.apache.directory.shared.kerberos.crypto.checksum.ChecksumType;


/**
 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
 */
class HmacMd5Checksum implements ChecksumEngine
{
    public ChecksumType checksumType()
    {
        return ChecksumType.HMAC_MD5;
    }


    public byte[] calculateChecksum( byte[] data, byte[] key, KeyUsage usage )
    {
        try
        {
            SecretKey sk = new SecretKeySpec( key, "ARCFOUR" );

            Mac mac = Mac.getInstance( "HmacMD5" );
            mac.init( sk );

            return mac.doFinal( data );
        }
        catch ( GeneralSecurityException nsae )
        {
            nsae.printStackTrace();
            return null;
        }
    }
}
