Attacks on a Privacy-Preserving Publish-Subscribe System and a Ride-Hailing Service

A privacy-preserving Context-Aware Publish-Subscribe System (CA-PSS) enables an intermediary (broker) to match the content from a publisher and subscription by subscriber based on current context while preserving confidentiality of subscriptions notifications. While Ride-Hailing Service (RHS) (service provider) ride request with taxi driver in privacy-friendly manner. In this work, we attack CA-PSS proposed Nabeel et al. (2013), where show that any entity system including broker can learn confidential subscribers. We also RHS called lpRide Yu (2019), rider/driver efficiently recover secret keys all other riders drivers. Also, will be able location rider. The attacks are our cryptanalysis modified Paillier cryptosystem forms building block for both above protocols.