We show that it is possible to achieve information theoretic location privacyfor secondary users (SUs) in database-driven cognitive radio networks (CRNs)with an end-to-end delay less than a second, which is significantly better thanthat of the existing alternatives offering only a computational privacy. Thisis achieved based on a keen observation that, by the requirement of FederalCommunications Commission (FCC), all certified spectrum databases synchronizetheir records. Hence, the same copy of spectrum database is available throughmultiple (distinct) providers. We harness the synergy between multi-serverprivate information retrieval (PIR) and database- driven CRN architecture tooffer an optimal level of privacy with high efficiency by exploiting thisobservation. We demonstrated, analytically and experimentally with deploymentson actual cloud systems that, our adaptations of multi-server PIR outperformthat of the (currently) fastest single-server PIR by a magnitude of times withinformation theoretic security, collusion resiliency, and fault-tolerancefeatures. Our analysis indicates that multi-server PIR is an idealcryptographic tool to provide location privacy in database-driven CRNs, inwhich the requirement of replicated databases is a natural part of the systemarchitecture, and therefore SUs can enjoy all advantages of multi-server PIRwithout any additional architectural and deployment costs.
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