ABAFOR: A Blockchain-based Privacy-Preserving Architecture for Efficient Contact Tracing and GIS Analysis

The Coronavirus disease 2019 has manifested into a global pandemic spreading into almost all the countries and territories in the world. Contact tracing, followed by testing and isolation, have been identified as important tools in containing the proliferation of the disease. Because of manual contact tracing limitations, smartphone apps for digital contact tracing have been deployed by authorities in multiple countries. However, many of these apps have faced criticism because of interoperability, privacy and security issues. This paper proposes an open architecture based on blockchain technology that addresses some of these criticisms. It enables interoperability through a publicly-readable consortium blockchain database, preserving privacy by distributing users’ partial identities among multiple decentralised authorities and providing security through digital signature and asymmetric key encryption. In addition, the architecture provides a fast proof-of-authority based consensus algorithm using reputation as a stake to add and validate blocks on the blockchain efficiently and a swift contact tracing algorithm using Spatio-temporal and key-valued databases.