Zone Check is based on the DP-3T standard which allows you to record infection-relevant contacts completely anonymously by using Bluetooth Low Energy (BLE). Generated data is only stored decentrally on the mobile device of the user. The app is based on separate native app developments for Android and iOS. The software and hardware architecture meets the highest data security standards and thus complies with the following principles:
The core functionality of the app is the contact scanner which is based on an anonymous ID exchange between the apps of two users. The functionality is illustrated in the graphic below.
If the contact scanner is activated on two devices, the app recognizes the other device via BLE and the User IDs are exchanged and stored locally. This exchange takes place when the persons were less than 2 meters away from each other and were in contact for at least 15 minutes. New User-IDs are generated decentrally by the app every 15 minutes.
If a person tests positive for COVID-19 and updates this information in the app, the IDs of the last 14 days are sent to the backend and from there they are broadcasted to the other relevant users. The app then compares the IDs on the end devices decentrally with those of the recorded contacts. Only the anonymous User-IDs of infected persons are temporarily (i.e. for 14 days) recorded on a central server. In the event of a match, users receive a push message about the contact with an infected person, including time and duration.