Block-HPCT: Blockchain Enabled Digital Health Passports and Contact Tracing of Infectious Diseases like COVID-19.

Due to its significant global impact, both domestic and international efforts are underway to cure the infection and stop the COVID-19 virus from spreading further. In resource-limited environments, overwhelmed healthcare institutions and surveillance systems are struggling to cope with this epidemic, necessitating a specific strategic response. In this study, we looked into the COVID-19 situation and to establish trust, accountability, and transparency, we employed blockchain's immutable and tamper-proof properties. We offered a smart contract (SC)-based solution (Block-HPCT) that has been successfully tested to preserve a digital health passport (DHP) for vaccine recipients; also, for contact tracing (CT) we employed proof of location concept, which aids in a swift and credible response directly from the appropriate healthcare authorities. To connect on-chain and off-chain data, trusted and registered oracles were integrated and to provide a double layer of security along with symmetric key encryption; both Interplanetary File System (IPFS) and Hyperledger Fabric were merged as storage center. We also provided a full description of the suggested solution's system design, implementation, experiment results, and evaluation (privacy and cost analysis). As per the findings, the suggested approach performed satisfactorily across all significant assessment criteria, implying that it can lead the way for practical implementations and also can be used for similar types of situations where contact tracing of infectious can be crucial.