Digital technology creates risks to people’s privacy in ways that did not exist before. I design end-to-end private systems to mitigate these real-world privacy risks. In this talk I will discuss my designs for two applications. These applications highlight key aspects of my work: I analyse security, privacy, and deployment requirements; and address these requirements by designing new cryptographic primitives and system architectures.

In the first part of this talk, I will focus on my DP-3T and CrowdNotifier designs for digital proximity and presence tracing that help mitigate the COVID-19 pandemic. These designs combine novel cryptographic primitives and communication systems to protect users’ privacy. The DP3T and CrowdNotifier designs have been deployed to millions of phones. In the second part of this talk, I will present DatashareNetwork, a document search system for investigative journalists that enables them to locate relevant documents for their investigations. DatashareNetwork combines a novel multi-set private set intersection primitive with anonymous communication and authentication systems to create a decentralised and privacy-friendly document search system.