Cellular Network Infrastructure » IMSI Pseudonymization

package org.osmocom.IMSIPseudo;

import javacard.framework.APDU;

import javacard.framework.Applet;

import javacard.framework.ISOException;

import sim.toolkit.EnvelopeHandler;

import sim.toolkit.ProactiveHandler;

import sim.toolkit.ToolkitConstants;

import sim.toolkit.ToolkitException;

import sim.toolkit.ToolkitInterface;

import sim.toolkit.ToolkitRegistry;

public class IMSIPseudo extends Applet implements ToolkitInterface, ToolkitConstants {

	// DON'T DECLARE USELESS INSTANCE VARIABLES! They get saved to the EEPROM,

	// which has a limited number of write cycles.

	private byte helloMenuItem;

	static byte[] welcomeMsg = new byte[] { 'H', 'e', 'l', 'l', 'o', ',', ' ',

						'W', 'o', 'r', 'l', 'd', '!' };

	static byte[] menuItemText = new byte[] { 'I', 'M', 'S', 'I', ' ', 'P', 's', 'e', 'u', 'd', 'o', 'n', 'y', 'm',

						  'i', 'z', 'a', 't', 'i', 'o', 'n'};

	private IMSIPseudo() {

		// This is the interface to the STK applet registry (which is separate

		// from the JavaCard applet registry!)

		ToolkitRegistry reg = ToolkitRegistry.getEntry();

		// Define the applet Menu Entry

		helloMenuItem = reg.initMenuEntry(menuItemText, (short)0, (short)menuItemText.length,

				PRO_CMD_SELECT_ITEM, false, (byte)0, (short)0);

		reg.setEvent(EVENT_EVENT_DOWNLOAD_LOCATION_STATUS);

	}

	// This method is called by the card when the applet is installed. You must

	// instantiate your applet and register it here.

	public static void install(byte[] bArray, short bOffset, byte bLength) {

		IMSIPseudo applet = new IMSIPseudo();

		applet.register();

	}

	// This processes APDUs sent directly to the applet. For STK applets, this

	// interface isn't really used.

	public void process(APDU arg0) throws ISOException {

		// ignore the applet select command dispached to the process

		if (selectingApplet())

			return;

	}

	// This processes STK events.

	public void processToolkit(byte event) throws ToolkitException {

		EnvelopeHandler envHdlr = EnvelopeHandler.getTheHandler();

		if (event == EVENT_MENU_SELECTION) {

			byte selectedItemId = envHdlr.getItemIdentifier();

			if (selectedItemId == helloMenuItem) {

				showHello();

			}

		}

		if (event == EVENT_EVENT_DOWNLOAD_LOCATION_STATUS) {

			/* TODO: count the location updates done with the same

			 * pseudo IMSI, and warn the user if it becomes too

			 * high */

			showHello();

		}

	}

	private void showHello() {

		ProactiveHandler proHdlr = ProactiveHandler.getTheHandler();

		proHdlr.initDisplayText((byte)0, DCS_8_BIT_DATA, welcomeMsg, (short)0,

				(short)(welcomeMsg.length));

		proHdlr.send();

		return;

	}

}