Abstract
Contact tracing has widely been adopted to control the spread of
Coronavirus-2019 (COVID-19). It enables to identify, assess, and manage
people who have been exposed to COVID-19, thereby preventing from its
further transmission. Today’s most of the contact tracing approaches,
tools, and solutions fall short in providing decentralized, transparent,
traceable, immutable, auditable, secure, and trustworthy features. In
this paper, we propose a decentralized blockchain-based COVID-19 contact
tracing solution. Contact tracing can greatly suffice the need for a
speedy response to a pandemic. We leverage the immutable and
tamper-proof features of blockchain to enforce trust, accountability,
and transparency. Trusted and registered oracles are used to bridge the
gap between on-chain and off-chain data. With no third parties involved
or centralized servers, the users’ medical information is not prone to
invasion, hacking, or abuse. Each user is registered using their digital
medical passports. To respect the privacy of the users, their locations
are updated with a time delay of 20 minutes. Using Ethereum smart
contracts, transactions are executed on-chain with emitted events and
immutable logs. We present details of the implemented algorithms and
their testing analysis. We evaluate the proposed approach using
security, cost, and privacy parameters to show its effectiveness. The
smart contracts code is publicly made available on GitHub.