src/org/simalliance/openmobileapi/service/security/gpac/dataobjects/NFC_AR_DO.java

/*
 * Copyright 2012 Giesecke & Devrient GmbH.
 *
 * 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 org.simalliance.openmobileapi.service.security.gpac.dataobjects;

import java.io.ByteArrayOutputStream;


/**
 * NFC-AR-DO:
 * In the NFC use case, mobile device application gather information 
 * from their associated card application using the SE access API. 
 * However, when the card application needs to trigger its associated mobile application, 
 * it sends an HCI EVT_TRANSACTION according to ETSI TS 102 622 [102 622] over SWP to the device. 
 * This event is handled by the NFC chipset stack which has to start 
 * the corresponding device application. Disclosure of this event to malicious applications 
 * can lead to phishing and denial of service attacks.
 * To prevent this, it shall be possible to use the applications signature to authorize 
 * device applications to receive HCI events issued by the secure element application.
 * An NFC event data object defines an access rule for generating NFC events for 
 * a specific terminal application. The NFC event access can be restricted by a rule based 
 * on an event access is NEVER/ ALWAYS allowed policy. 
 *
 * 
 *
 */
public class NFC_AR_DO extends BerTlv {
	
	public final static int _TAG = 0xD1;

	private boolean mNfcAllowed = false;
	
	public NFC_AR_DO(byte[] rawData, int valueIndex, int valueLength) {
		super(rawData, _TAG, valueIndex, valueLength);
	}
	
	public NFC_AR_DO( boolean allowed ){
		super( null, _TAG, 0, 0);
		mNfcAllowed = allowed;
	}
	
	public boolean isNfcAllowed(){
		return mNfcAllowed;
	}

	@Override
	/**
	 * Tag: D1
	 * Length: 1
	 * Value: 
	 * Contains a NFC event access rule:
	 * NEVER (00): NFC event access is not allowed
	 * ALWAYS(01): NFC event access is allowed
     *
	 */
	public void interpret() 
		throws ParserException {

		mNfcAllowed = false;
		
		byte[] data = getRawData();
		int index = getValueIndex();
		
		if( index + getValueLength() > data.length){
			throw new ParserException( "Not enough data for NFC_AR_DO!");
		}
		
		if( getValueLength() != 1 ){
			throw new ParserException( "Invalid length of NFC-AR-DO!" );
		}
		mNfcAllowed = (data[index] == 0x01);
	}
	
	@Override
	/**
	 * Tag: D1
	 * Length: 1
	 * Value: 
	 * Contains a NFC event access rule:
	 * NEVER (00): NFC event access is not allowed
	 * ALWAYS(01): NFC event access is allowed
     *
	 */
	public void build( ByteArrayOutputStream stream )
		throws DO_Exception {

		// write tag
		stream.write(getTag());
		stream.write(0x01);
		stream.write(mNfcAllowed ? 0x01 : 0x00 );
	}
	
}