What technology does the app use?
- The app generates a unique code for each phone. This code does not contain any information about you or your phone. The code is random and changes every 15 minutes.
- Phones share these codes when they are near to each other. If someone around you also has the app installed, your phones will share codes using Bluetooth Low Energy. The stronger the signal, the closer you are. This enables the app to know which phones have been nearby. The app does not know who owns the phones, or where you were at the time.
- If an app user tests positive for the coronavirus, that person can upload his/her codes to a server. The server only stores the codes of infected people. To add the codes to the server, the user first needs to enter a GGD key in the app. The GGD key ensures that the codes added to the server really do belong to someone who has tested positive for the coronavirus. All codes older than 14 days are deleted from the server automatically.
- Every phone checks whether it has been near infected people by checking the codes on the server. The app contacts the server to check for the codes of infected persons several times a day. It compares the server codes with the codes that are stored on your phone. This allows the app to see if there is a risk that you have been infected.
- If codes from an infected person are on your phone, you will get a notification. A notification that you are at risk is confirmation that you have spent more than 15 minutes near one or more people who later tested positive for the coronavirus. The notification will tell you when you were near the infected person. It will not tell you who that person was or where you were when you were near them. The app will also advise you what to do next. Your own codes will not be uploaded to the server. They will be stored on your phone for the next 14 days.
The measurements performed by the CoronaMelder app add up. Since the introduction of version 2.0 of the CoronaMelder app, you will also get a notification if you have been close to more than one infected person on more than one occasion on the same day and those contacts add up to 15 minutes within a distance of 1.5 metres.