SNARKs to the rescue: proof-of-contact in zero knowledge
This addresses privacy and scalability issues in automated contact tracing for public health during pandemics, though it appears incremental as it builds on existing SNARKs and contact tracing concepts.
The paper tackles COVID-19 contact tracing by developing a decentralized protocol using zero-knowledge proofs, allowing infected individuals to cryptographically prove contact with others without revealing identities, and extends this to proofs of nth-order exposure to speed up tracing.
This paper describes techniques to help with COVID-19 automated contact tracing, and with the restoration efforts. We describe a decentralized protocol for ``proof-of-contact'' in zero knowledge where a person can publish a short cryptographic proof attesting to the fact that they have been infected and that they have come in contact with a set of people without revealing any information about any of the people involved. More importantly, we describe how to compose these proofs to support broader functionality such as proofs of $n$th-order exposure which can further speed up automated contact tracing. The cryptographic proofs are publicly verifiable, and places the burden on the person proving contact and not on third parties or healthcare providers rendering the system more decentralized, and accordingly more scalable.