From Confidential kNN Queries to Confidential Content-based Publish/Subscribe

Content-based publish/subscribe (pub/sub) is an effective paradigm for information dissemination in distributed systems. In brief, publishers generate feeds of information, and subscriber clients register their interests with a pub/sub service tasked with delivering the published data to interested subscribers. Modern pub/sub services are often externalized to public clouds. This brings economic advantages that are unfortunately overshadowed by associated security risks, in particular related to the confidentiality of both the published data as well as of the subscriptions. Guaranteeing confidentiality for content-based pub/sub in an efficient fashion is an active research area. A promising direction is to leverage specific cryptographic solutions that permit the execution of the pub/sub service over encrypted data. In this article we describe a simple and general methodology to derive new mechanisms for pub/sub confidentiality out of another category of data protection schemes: confi dential kNN query mechanisms designed for encrypted databases. We exemplify this framework with a concrete use case. We believe that this initial step will lead to more secure and efficient adaptations of kNN solutions to the pub/sub domain.