A Zero-Knowledge-Range-Proof-based Privacy-Preserving Blockchain Platform for COVID-19 Contact Tracing

Abstract

Contact tracing is an effective strategy to slow down the COVID-19 pandemic. However, the use of digital footprints as supportive evidences in the contact tracing process rises the privacy problems since private information must be shared to the contact tracing providers. This paper proposed a novel privacy-preserving contact tracing procedure based on zero-knowledge-range-proof and blockchain platform, which helps users to prove whether they in contact with the confirmed patient without disclosing the exact location they have visited. The blockchain is used to guarantee anonymity through the use of address as an identity, and provide strong non-repudiation from transactions. Finally, we provide a proof-of-concept implementation of our proposal using Hyperledger Fabric and smartphone application. The evaluation showed that the proposed system can work as intended with minimal processing delay.