Weakly Secure Coded Caching Scheme for an Eavesdropper Having Prior Knowledge

Abstract

Coded caching is a promising method for solving caching problems in content-centric wireless networks. To enhance the security of coded caching for practical purposes, this paper investigates a secure coded caching scheme for defending against an eavesdropper who may possess prior knowledge before eavesdropping on content delivery. a novel key-based solution is proposed to minimize the leakage of meaningful information to the eavesdropper during the delivery phase. In the proposed solution, the central server observes the strength of the eavesdropper and introduces several keys to dynamically encrypt the broadcast signals within a weak security constraint. The amount of cache memory occupied by the keys is carefully designed to achieve the highest possible cache gain in terms of the rate of content delivery. The tradeoff between the cache memory usage and the transmission rate with varying eavesdropper strength is characterized. For a given size of the total cache memory, the tradeoff between the amounts of memory used for data and key storage is also presented. We report simulation results to support our analytical findings and show that no keys are needed to achieve weak security against a low-strength eavesdropper. Even for an eavesdropper of high strength, weak security can be introduced at a negligible cost given a large cache size.