STAR SDK Android

Moved to DP-3T!

As of May 2020, all of our efforts are transitioning to DP-3T.

Introduction

This is the Android version of the Secure Tag for Approach Recognition (STAR) SDK. The idea of the sdk is, to provide a SDK, which enables an easy way to provide methods for contact tracing. This project was built within 71 hours at the HackZurich Hackathon 2020.

Architecture

There exists a central discovery server on Github. This server provides the necessary information for the SDK to initialize itself. After the SDK loaded the base url for its own backend it will load the infected list from there, as well as post if a user is infected.

The backend should hence gather all the infected list from other backends and provide a collected list from all sources. As long as the keys are generated with the SDK we can validate them across different apps.

Further Documentation

There exists a documentation repository in the STAR Organization. It includes Swager YAMLs for the backend API definitions, as well as some more technical details on how the keys are generated and how the validation mechanism works

Function overview

Initialization

Name	Description	Function Name
initWithAppId	Initializes the SDK and configures it	public static void init(Context context, String appId)

Methods

Name	Description	Function Name
start	Starts Bluetooth tracing	public static void start(Context context)
stop	Stops Bluetooth tracing	public static void stop(Context context)
sync	Pro-actively triggers sync with backend to refresh exposed list	public static void sync(Context context)
status	- number_of_handshakes : Number - tracking_active : Bool - was_contact_exposed : Bool - last_sync_update - am_i_exposed - error (permission, bluetooth disabled, no network, ...) : Enum	public static TracingStatus getStatus(Context context)
i_was_exposed : Custom object with additional data	This method must be called upon positive test or whatever	public static void sendIWasExposed(Context context, Object customData, CallbackListener<Void> callback)
i_am_healed	Resets am_i_exposed and regenerates key	public static void sendIWasHealed(Context context, Object customData, CallbackListener<Void> callback)
reset	Removes all SDK related data (key and database) and de-initializes SDK	public static void reset(Context context)

Broadcast

Name	Description	Function Name
status update	Status was updated; new status can be fetched with the status method	Register for Broadcast with the IntentFilter returned by public static IntentFilter getUpdateIntentFilter()

Building a AAR

To build an aar file that you can include in your project use:

$ ./gradlew assemble

The library is generated under sdk/build/outputs/aar

Integrating into a Project

Include the builded aar file by adding it to your project. Make sure that you also include the following dependencies:

implementation 'androidx.core:core:1.2.0'
implementation "androidx.security:security-crypto:1.0.0-beta01"
implementation 'androidx.work:work-runtime:2.3.4'

implementation 'com.squareup.retrofit2:retrofit:2.6.2'
implementation 'com.squareup.retrofit2:converter-gson:2.6.2'

Using the SDK

Initialization

In your Application.onCreate() you have to initialize the SDK with:

STARTracing.init(getContext(), "com.exmaple.your.app");

The provided app name has to be registered in the discovery service on Github

Start / Stop tracing

To start and stop tracing use

STARTracing.start(getContext());
STARTracing.stop(getContext());

Make sure that the user has the permission Manifest.permission.ACCESS_FINE_LOCATION granted, Bluetooth is enabled and BatteryOptimization is disabled. BatteryOptimization can be checked with

PowerManager powerManager = (PowerManager) getContext().getSystemService(Context.POWER_SERVICE);
boolean batteryOptDeact = powerManager.isIgnoringBatteryOptimizations(getContext().getPackageName());

and for asking the user to disable the optimization use:

startActivity(new Intent(Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS,
					Uri.parse("package:" + getContext().getPackageName())));

Tracing is automatically restarted if the phone is rebooted by the SDK, it is enough to call start() once from your app.

Customize tracing notification

The tracing happens in a foreground service and therefore displays a notification. This notification can be customized by defining the following string resources in your project:

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<string name="star_sdk_service_notification_channel">@string/app_name</string>
	<string name="star_sdk_service_notification_title">@string/app_name</string>
	<string name="star_sdk_service_notification_text">@string/foreground_service_notification_text</string>
</resources>

To change the notification icon add your custom ic_begegnungen drawable to the project.

Checking the current tracing status

TracingStatus status = STARTracing.getStatus(getContext());

The TracingStatus object contains all information of the current tracing status.

To get notified when the status changes, you can register a broadcast receiver with

getContext().registerReceiver(broadcastReceiver, STARTracing.getUpdateIntentFilter());

Report user exposed

STARTracing.sendIWasExposed(getContext(), null, new CallbackListener<Void>() {
				@Override
				public void onSuccess(Void response) {
				}

				@Override
				public void onError(Throwable throwable) {
				}
			});

Sync with backend for exposed user

The SDK automatically registers a periodic Job to sync with the backend for new exposed users. If you want to trigger a sync manually (eg. upon a push from your backend) you can use:

STARTracing.sync(getContext());

Make sure you do not call this method on the UI thread, because it will perform the sync synchronously.