  Several contact tracing solutions have been proposed and implemented all
around the globe to combat the spread of COVID-19 pandemic. But, most of these
solutions endanger the privacy rights of the individuals and hinder their
widespread adoption. We propose a privacy-preserving contact tracing protocol
for the efficient tracing of the spread of the global pandemic. It is based on
the private set intersection (PSI) protocol and utilizes the homomorphic
properties to preserve the privacy at the individual level. A hierarchical
model for the representation of landscapes and rate-limiting factor on the
number of queries have been adopted to maintain the efficiency of the protocol.
