Today, vast amounts of location data are collected by various service
providers. These location data owners have a good idea of where their users are
most of the time. Other businesses also want to use this information for
location analytics, such as finding the optimal location for a new branch.
However, location data owners cannot share their data with other businesses,
mainly due to privacy and legal concerns. In this paper, we propose
privacy-preserving solutions in which location-based queries can be answered by
data owners without sharing their data with other businesses and without
accessing sensitive information such as the customer list of the businesses
that send the query. We utilize a partially homomorphic cryptosystem as the
building block of the proposed protocols. We prove the security of the
protocols in semi-honest threat model. We also explain how to achieve
differential privacy in the proposed protocols and discuss its impact on
utility. We evaluate the performance of the protocols with real and synthetic
datasets and show that the proposed solutions are highly practical. The
proposed solutions will facilitate an effective sharing of sensitive data
between entities and joint analytics in a wide range of applications without
violating their customers' privacy.Comment: IEEE Transactions on Dependable and Secure Computing, 201