CrySP Speaker Series on Privacy

This speaker series is made possible by an anonymous charitable donation in memory of cypherpunks and privacy advocates Len Sassaman, Hugh Daniel, Hal Finney, and Caspar Bowden.

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Privacy-friendly presence and proximity tracing

Wouter Lueks, EPFL

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November 24, 2021 11:00am, in Zoom


Ever since the start of the COVID-19 pandemic, there has been a push to deploy technology as a means of pandemic mitigation. In this talk I'll focus on two such systems. Both aim to notify users that have been exposed to somebody with COVID-19 and that should therefore take precautions such as quarantining or getting a test. The first system, designed by DP3T, notifies users that were close enough for long enough to a positive person. The second, CrowdNotifier, instead notifies users that where in an indoor space (e.g., bar, restaurant, lecture room) with a positive person.

Deploying such systems comes with security and privacy risks. Especially when rolling them out to large fractions of the population, or when making them de facto mandatory, e.g., to go to a restaurant. In this talk I will discuss these risks, and explain how we designed, implemented and deployed both systems to mitigate these risks.


Wouter Lueks is a postdoctoral researcher at EPFL in Lausanne. He designs, builds and deploys privacy-friendly systems. To do so, he combines applied cryptography, privacy and requirements modeling, and clever systems engineering. He has worked on several systems such as IRMA for anonymous authentication, a secure document search system for investigative journalists called DatashareNetwork, and more recently, on designing, analyzing, and implementing digital proximity and presence tracing systems.