TrueCrypt Widget

Some time ago I've shown you Password Manager application. This post is also related to passwords. I've created a very simple widget that uses InputStick to type my TrueCrypt password for encrypted system partition. The most important fact is that now all it takes to type the password is just a single click.

Here's a quick comparison of steps required to type the password:

Password Manager:

1. Run application.
2. Type master password.
3. Connect to InputStick (although auto connect feature will be added).
4. Click on "TrueCrypt" item.
5. Select  "Password" entry.
6. Press "Type" button.

Widget:

1. Click on the widget.

In both cases it is assumed that there is only one InputStick paired with the phone, otherwise you have to manually select InputStick device (unless DeviceManager is set to always connect to "Default" device). Also, I assume that Bluetooth radio is already on, if not you will be asked if you want to enable it.

But what about security? Is it safe this way? Well, in this case I think that it is:

• TrueCrypt is used to protect data in case my laptop gets lost or stolen.
• If I loose both my laptop and phone, it is still protected by relatively complex pattern lock.
• Even if phone is unlocked the only (simple) way to get the password is to type it with InputStick, there is no "show plaintext" option.
• Data stored on system partition is not something that can be remotely accessed, unlike, for example: email account.

So the only scenario in which my data can be compromised is when I loose all three devices: laptop, phone, InputStick and somehow phone remains unlocked. In my opinion: highly unlikely. However, for anything that can be remotely accessed I will still use Password Manager.

Here you can see the widget conveniently placed on my homescreen:

TrueCrypt Widget placed on homescreen.

After clicking on it, it hides icon and shows progress bar. When everything is done, it returns to initial state.

TrueCrypt Widget at work :)

And here's a short video showing how this actually works:

Also, if anyone is interested, take a look at the source code. Most part of the widget is based on this tutorial.

Main widget class: MyWidget.java:

	package com.example.mywidget;
	import android.app.PendingIntent;
	import android.appwidget.AppWidgetManager;
	import android.appwidget.AppWidgetProvider;
	import android.content.ComponentName;
	import android.content.Context;
	import android.content.Intent;
	import android.view.View;
	import android.widget.RemoteViews;
	public class MyWidget extends AppWidgetProvider {
	public static final String BTN_CLICKED = "buttonClick";
	public static final String BTN_READY = "buttonReady";
	@Override
	public void onUpdate(Context context, AppWidgetManager appWidgetManager,
	int[] appWidgetIds) {
	RemoteViews remoteViews;
	ComponentName watchWidget;
	remoteViews = new RemoteViews(context.getPackageName(),
	R.layout.my_layout);
	watchWidget = new ComponentName(context, MyWidget.class);
	Intent intent = new Intent(context, getClass());
	intent.setAction(BTN_CLICKED);
	remoteViews.setOnClickPendingIntent(R.id.button,
	PendingIntent.getBroadcast(context, 0, intent, 0));
	appWidgetManager.updateAppWidget(watchWidget, remoteViews);
	}
	@Override
	public void onReceive(Context context, Intent intent) {
	// TODO Auto-generated method stub
	super.onReceive(context, intent);
	if (BTN_CLICKED.equals(intent.getAction())) {
	context.startService(new Intent(context, WidgetService.class));
	AppWidgetManager appWidgetManager = AppWidgetManager
	.getInstance(context);
	RemoteViews remoteViews;
	ComponentName watchWidget;
	remoteViews = new RemoteViews(context.getPackageName(),
	R.layout.my_layout);
	watchWidget = new ComponentName(context, MyWidget.class);
	remoteViews.setViewVisibility(R.id.button, View.GONE);
	remoteViews.setViewVisibility(R.id.progressBar, View.VISIBLE);
	appWidgetManager.updateAppWidget(watchWidget, remoteViews);
	}
	if (BTN_READY.equals(intent.getAction())) {
	AppWidgetManager appWidgetManager = AppWidgetManager
	.getInstance(context);
	RemoteViews remoteViews;
	ComponentName watchWidget;
	remoteViews = new RemoteViews(context.getPackageName(),
	R.layout.my_layout);
	watchWidget = new ComponentName(context, MyWidget.class);
	remoteViews.setViewVisibility(R.id.button, View.VISIBLE);
	remoteViews.setViewVisibility(R.id.progressBar, View.GONE);
	appWidgetManager.updateAppWidget(watchWidget, remoteViews);
	}
	}
	}

view raw MyWidget.java hosted with ❤ by GitHub

Background service, which is actually doing all the work: WidgetService.java

	package com.example.mywidget;
	import android.app.Service;
	import android.content.Intent;
	import android.os.IBinder;
	import com.example.inputsticklibrary.usb.USBDevice;
	import com.example.inputsticklibrary.usb.USBDeviceListener;
	import com.example.inputsticklibrary.usb.devices.USBKeyboard;
	public class WidgetService extends Service implements USBDeviceListener {
	private static final USBKeyboard keyb = new USBKeyboard();
	private static boolean running;
	@Override
	public void onUSBEvent(int code) {
	// TODO Auto-generated method stub
	int state = keyb.getState();
	if (state == USBDevice.STATE_READY) {
	if (!running) {
	running = true;
	Thread t = new Thread() {
	@Override
	public void run() {
	try {
	// wait a bit to be sure its 100% ready
	Thread.sleep(1000);
	// type password
	keyb.type("passwordgoeshere");
	// press enter
	keyb.pressAndRelease(USBKeyboard.NONE,
	USBKeyboard.KEY_ENTER);
	// wait for long enough to allow USB host read all
	// characters
	Thread.sleep(1000);
	keyb.disconnect();
	running = false;
	} catch (Exception e) {
	e.printStackTrace();
	}
	}
	};
	t.start();
	} else {
	this.stopSelf();
	}
	}
	if (state == USBDevice.STATE_NONE) {
	keyb.unregisterListener();
	this.stopSelf();
	}
	}
	@Override
	public void onUSBData(int endpoint, byte[] data) {
	// TODO Auto-generated method stub
	}
	@Override
	public IBinder onBind(Intent arg0) {
	// TODO Auto-generated method stub
	return null;
	}
	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
	running = false;
	keyb.setContext(this.getApplicationContext());
	keyb.registerListener(this);
	if (keyb.getState() == USBDevice.STATE_NONE) {
	keyb.connect();
	} else {
	this.stopSelf();
	}
	return START_STICKY;
	}
	@Override
	public void onDestroy() {
	Intent i = new Intent(this, MyWidget.class);
	i.setAction(MyWidget.BTN_READY);
	this.sendBroadcast(i);
	super.onDestroy();
	}
	}

view raw WidgetService.java hosted with ❤ by GitHub