DP3T-SDK for Android

DP3T

The Decentralised Privacy-Preserving Proximity Tracing (DP-3T) project is an open protocol for COVID-19 proximity tracing using Bluetooth Low Energy functionality on mobile devices that ensures personal data and computation stays entirely on an individual's phone. It was produced by a core team of over 25 scientists and academic researchers from across Europe. It has also been scrutinized and improved by the wider community.

DP-3T is a free-standing effort started at EPFL and ETHZ that produced this protocol and that is implementing it in an open-sourced app and server.

Introduction

This is the first implementation of the DP-3T "low bandwidth" protocol. The current implementation does not use the as yet unreleased "Contact Tracing" API of Apple/Google--and has limitations as a result. Our "hybrid approach" uses Bluetooth Low Energy (BLE) to exchange EphIDs. It uses advertisements whenever possible and falls back to GATT Server connections if not possible to transmit/collect an EphID this way (e.g., on iOS devices when the app is in background). This approach can result in higher energy consumption and scalability issues and will be replaced by the Apple/Google API.

Our immediate roadmap is: to support the Apple/Google wire protocol, to be forward-compatible, and to support the actual Apple/Google API as soon as it is released to iOS and Android devices.

Repositories

• Android SDK & Calibration app: dp3t-sdk-android
• iOS SDK & Calibration app: dp3t-sdk-ios
• Android Demo App: dp3t-app-android
• iOS Demo App: dp3t-app-ios
• Backend SDK: dp3t-sdk-backend

Work in Progress

The DP3T-SDK for Android contains alpha-quality code only and is not yet complete. It has not yet been reviewed or audited for security and compatibility. We are both continuing the development and have started a security review. This project is truly open-source and we welcome any feedback on the code regarding both the implementation and security aspects. This repository contains the open prototype SDK, so please focus your feedback for this repository on implementation issues.

Further Documentation

The full set of documents for DP3T is at https://github.com/DP-3T/documents. Please refer to the technical documents and whitepapers for a description of the implementation.

Architecture

A central discovery service is hosted on Github. This server provides the necessary information for the SDK to initialize itself. After the SDK loads the base url for its own backend, it will load the infected list from there, as well as post if a user is infected. This will also allow apps to fetch lists from other backend systems participating in this scheme and can handle roaming of users.

Calibration App

Included in this repository is a Calibration App that can run, debug and test the SDK directly without implementing it in a new app first. It collects additional data and stores it locally into a database to allow for tests with phones from different vendors. Various parameters of the SDK are exposed and can be changed at runtime. Additionally it provides an overview of how to use the SDK.

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	Returns a TracingStatus-Object describing the current state. This contains: - numberOfContacts : int - advertising : boolean - receiving : boolean - lastSyncUpdate:long - infectionStatus:InfectionStatus - matchedContacts:List<MatchedContact> - errors (permission, bluetooth disabled, no network, ...) : List<ErrorState>	public static TracingStatus getStatus(Context context)
I infected	This method must be called upon positive test.	public static void sendIAmInfected(Context context, Date onset, ExposeeAuthData exposeeAuthData, CallbackListener<Void> callback)
clearData	Removes all SDK related data (key and database) and de-initializes SDK	public static void clearData(Context context, Runnable onDeleteListener)

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 in the folder dp3t-sdk:

$ ./gradlew assemble

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

Integrating into a Project

The SDK is available on JCenter and can be included directly as Gradle dependency:

dependencies {
implementation 'org.dpppt:dp3t-sdk-android:0.1.0'
}

Using the SDK

Initialization

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

DP3T.init(getContext(), "com.example.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

DP3T.start(getContext());
DP3T.stop(getContext());

Make sure that the user has the permission Manifest.permission.ACCESS_FINE_LOCATION granted (this coarse-grained permission is required for any app with Bluetooth activity; our SDK uses BLE beaconing but does not require any "location" data), 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="dp3t_sdk_service_notification_channel">@string/app_name</string>
	<string name="dp3t_">@string/app_name</string>
	<string name="dp3t_sdk_service_notification_text">@string/foreground_service_notification_text</string>
</resources>

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

Checking the current tracing status

TracingStatus status = DP3T.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, DP3T.getUpdateIntentFilter());

Report user exposed

DP3T.sendIWasExposed(getContext(), null, new CallbackListener<Void>() {
				@Override
				public void onSuccess(Void response) {
				}

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

Sync with backend for exposed users

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

DP3T.sync(getContext());

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

License

This project is licensed under the terms of the MPL 2 license. See the LICENSE file.