Blockchain Driven Privacy Preserving Contact Tracing Framework in COVID-19

Contact tracing has been proven an effective approach to mitigate the virus spread in pandemics like COVID-19. As an emerging powerful decentralized data sharing and storage technique, blockchain has been explored to ensure data privacy and security in contact tracing processes. Existing work mostly treats blockchain as a separate storage system requiring third-party servers to perform data collection and computation, and avoids revealing detailed interior design of blockchain storage. However, blockchain system is capable to work as a fully automatic distributed contact tracing system without any third-party server by tackling the following challenges: 1) how to ensure the contact tracing correctness without compromising privacy; 2) how to design efficient and effective consensus mechanism to ensure the system security and robustness; 3) how to design an incentive mechanism to motivate people to behave honestly. In this article, we present the Blockchain Based Contact Tracing Framework for the contact tracing problem. In the framework, RSA encryption based transaction verification algorithm (RSA-TVA) is proposed to ensure contact tracing correctness, which can achieve more than 97% contact case recording accuracy even when each person has 60% chance of failing to verify the contact information. Reputation Corrected Delegated Proof of Stack (RC-DPoS) consensus mechanism is applied to jointly work with the proposed incentive mechanism, which can ensure timeliness of reporting contact cases and meanwhile balance the reward gained by different people. A novel contact tracing simulation environment is created in the simulation part, which considers three different contact scenarios. The simulation results demonstrate the effectiveness, robustness and attack resistance of RSA-TVA and RC-DPoS in the proposed Blockchain Based Contact Tracing Framework.