Keeping track of all contacts in Covid 19 cases as complete as possible is crucial in the fight against Corona. A special app technology should help with this. An overview of what the technology can and cannot do.
Efforts to contain the corona pandemic are still in full swing in Germany. On Wednesday, the federal and state governments announced which measures are planned and which are particularly important in the coming weeks. In addition to maintaining contact restrictions, those responsible also rely on “full contact tracking”. Because only if all contacts have one Covid-19 infected person can be identified and notified, an undetected spread of the virus can be effectively contained.
An important, supportive tool should be a tracing app: It should automatically record all the contacts of the respective smartphone owner and – should it turn out that one of them had Covid-19 – warn the owner so that they can be tested and can quarantine.
The biggest question is: How can an app do this without blatantly violating applicable data protection rules? And how should wild growth of noisy, incompatible apps be prevented?
The answer to which the federal and state governments have now agreed is PEPP-PT. The abbreviation stands for the name monster “Pan-European Privacy-Preserving Proximity Tracing”, an amalgamation of over 130 European scientists and experts from well-known research institutes and tech companies.
Together, they developed an open-source app technology that uses the Bluetooth– Recognizes radio standards of close contacts between smartphone users and saves them anonymously. App developers should access this technology and corresponding apps for Smartphones can develop.
How exactly does the PEPP-P workT technology?
A finished app can be installed and used voluntarily. When the app is started, the device is provided with an anonymous and time-limited identification number.
The app now uses the energy-saving wireless technology Bluetooth LE (Low Energy) and continuously searches for other smartphones within a radius of about two meters around the device, on which the app is also installed. If such a device is closer than two meters to your own device for a relevant period of time, for example at least 15 minutes, this is recorded as a relevant contact.
The devices only send each other the anonymous identification number, nothing else. It is stored encrypted on the two cell phones. As soon as a user of the app is a confirmed Covid 19 case, he can share his saved contacts via the app. These are sent to the server. All devices with an installed app regularly check on this server whether their identification number has been stored there. If the app finds the number of its own device, it informs the user that there has been contact with a Covid 19 patient and that he should report to the health department.
Why Bluetooth and not GPS or cell location?
Technologies like that Satellite-based positioning via GPS or radio cell location via the cell phone providers have two major disadvantages. First, they are too imprecise: the GPS-Positioning with a cell phone can be several meters away even under optimal conditions. It is not possible to determine whether two users are closer than two meters. It works indoors technology usually not at all. The radio cell location is also far too imprecise for this application.
Both are problematic for another reason as well: Using the position data, movement profiles of the users could be created, and users would also be clearly recognizable – location-related data is therefore in no way anonymous and data protection friendly.
Bluetooth, on the other hand, is a mere radio transmission technology. Two Bluetooth devices measure the distance to each other via RSSI (abbreviation for “Received Signal Strength Indicator”). This means that the distance is estimated using the intensity of the Bluetooth signal. Due to the reduced transmission power, the range here is only a few meters – and thus fits exactly to the requirements of the tracing app.
In modern smartphones, Bluetooth is already permanently activated by default and is looking for other devices – such as Bluetooth headphones – with which it should be linked. So you don’t have to worry about a noticeably increased battery consumption.
What can the planned tracing apps not do?
Of course, such tracing apps cannot guarantee absolute security. There are several reasons for this: The distance determination via RSSI is not a real distance measurement but an estimate and also not particularly accurate: How strong a Bluetooth signal depends not only on the distance between the two devices, but also on the individual smartphone model, how the user holds the device in his hand or whether it is open on the table or buried deep in a pocket.
And if you have the app but don’t always have your cell phone on your body, you can also get in touch with a Covid 19 patient unnoticed – there are numerous other ways in which the system can be wrong or simply have no chance of becoming infected to recognize.
However, users of Bluetooth trackers such as “Tile” and similar chips know that the technology basically works in everyday life, who find their misplaced key or wallet millions of times every day. Widely used, such a tracing app could certainly warn countless potentially infected people who could never have been identified and notified in any other way.
Are Google and Apple planning a competitor app?
Actually have Both manufacturers announced that they would jointly develop a very similar tracing function for their smartphone operating systems and make it available soon. This has several advantages: Google For example, has announced that the tracing functionality will be played out as an operating system update – this should reach significantly more people than through a separate app that first has to be searched for and downloaded. However, the use of the functionality remains a voluntary “opt-in” Apple and Google, users have to activate this themselves.
Unlike a normal app developer, Apple and Google also have the option of optimally embedding the function in the operating system and thus significantly better ensuring that it always works as it should and possibly give the application priorities that a normal app would not have.
Above all, however, the companies have declared that they will work with the respective health authorities in the individual countries and provide them with the data. It is therefore conceivable that the Apple and Google functions can be integrated into an existing tracing app system of the health authorities or could make a separate app unnecessary at a later date. So far, however, this cannot really be assessed, since neither approach has been completed.