Heatmap BLE-Kontakte auf BitsaboutMe

In the fight against the Corona virus the use of contact tracing apps is heavily discussed, especially for the upcoming reopen phase. The experiences in China, South Korea and Singapore shows that contact tracing apps effectively support the interruption of chains of infection. Depending on the political system, however, these apps collect a variety of sensitive data. It might include GPS, Bluetooth, phone number, credit card information and much more. This poses a potential risk to the users’ privacy and a potential gateway for the misuse of personal information.

In Europe, privacy is a high value asset. For this reason, Bluetooth Low Energy (BLE) has been identified as a possible technology to anonymously track contacts. Here you can learn more about the fundamental principle of this approach.

It is our mission to give users transparency and control over their BLE data. For this purpose, the new Android app (available on Play Store) of BitsaboutMe detects BLE devices in the immediate vicinity of the user. These can be smartphones and many other mobile devices, such as headsets, smart watches, speakers and more, as well as permanently installed BT beacons. Not all of these devices can be assigned as clearly as Corona tracing apps will. We therefore display all devices that have been recognized for at least 2 minutes with a certain strength, i.e. in the immediate vicinity of the user. However, distance measurement via BLE is error-prone, as the signal strength depends on many different factors (tissues, facilites, etc.).

At BitsaboutMe, we were quite surprised how widespread BLE has become. There can be no question that this topic only turned out to be interesting with the advent of Corona apps. Walking through Bern, you can record hundreds of Bluetooth (BT) contacts in a few minutes. Apple iPhones are currently of particular importance in this measurement. The reason for this is that they send out their own beacon signal and can be detected by it. iPhones and most other BLE devices protect the privacy of their users by sending out an anonymous identification number (the so called “MAC address”). The MAC address changes randomly every 10-15 minutes. This prevents a user from being tracked by his ID for a long period of time. However, this also means that when counting BT contacts, individual devices will appear multiple times.

You can therefore not equate the number of devices with the absolute number of actual contacts. The number should rather be considered in relative terms, e.g. to understand where and when you were exposed to more or less BT contacts. This can thus help to measure the success of your own social distancing behavior. Once contact-tracing apps are taking root, we will report these signals separately. So you can be sure that the source is another person using the app in question.

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