This repository puts forward a proposal for a secure, decentralized, privacy-preserving presence tracing system. Our proposal aims to simplify and accelerate the process of notifying individuals that shared a semi-public location with a SARS-CoV-2-positive person for a prolonged time without introducing new risks for users and locations. Existing proximity tracing systems (apps for contact tracing such as SwissCovid, Corona Warn App, and Immuni) notify only a subset of these people: those that were close enough for long enough. Current events have shown the need to notify all people that shared a space with a SARS-CoV-2-positive person. The proposed system aims to provide an alternative to increasing use of apps with similar intentions based on invasive collection or that are prone to abuse by authorities. Our preliminary design aims to minimize privacy and security risks for individuals and communities, while guaranteeing the highest level of data protection and good usability and deployability.

With this proposal, we seek feedback from a broad audience on the high-level design, its security and privacy properties, and the functionality it offers, so that the merits of the design can be discussed, and protection mechanisms can be added to correct weaknesses. We feel it is essential that designs be made public so the community as a whole can discuss the proposal and verify the claimed privacy guarantees before applications are deployed.

We are a international consortium of technologists, legal experts, engineers and epidemiologists with a wide range of experience who are interested in ensuring that any presence tracing technology does not result in governments obtaining surveillance capabilities which will endanger civil society.

The following people are behind this design:

EPFL: Prof. Carmela Troncoso, Prof. Marcel Salathé, Prof. Edouard Bugnion, Dr. Wouter Lueks
TU Delft: Prof. Seda Gürses
University College London: Dr. Michael Veale

This consortium overlaps with the DP3T consortium, but we stress that these are separate projects.

Everyone interacting on the CrowdNotifier projects codebases, issue trackers, etc. is expected to follow the code of conduct.