What is it? a mobile app
What does it do? trace interactions between users
What processes and technology does it use? it uses bluetooth.
In particular it automatically collects and locally stores encrypted contact information of other users in its proximity. If a user is confirmed to be SARS-CoV-2 positive, App can enter to “infected mode” and transmit an automatic “virus notification” message to all past, present and future contacts (within designed time limit in which the user can be contagious).
The collection of contact information, thus the code to implement it, is common to many other similar apps, see for example the PEPP-PT or the DP-3T or the Google and Apple frameworks. The anonymous virus-notification message can be transmitted using the “sealed sender messages” technology developed by the open-source app Signal messenger.