Key Superposition Simultaneously Achieves Security and Privacy in Cache-Aided Linear Function Retrieval

This work investigates the problem of cache-aided content Secure and demand Private Linear Function Retrieval (SP-LFR), where three constraints are imposed on system: (a) each user is interested in retrieving an arbitrary linear combination files server’s library; (b) library must be kept secure from a wiretapper who obtains signal sent by server; (c) no subset colluding users together can obtain information about demands remaining users. A procedure proposed to derive SP-LFR scheme given Placement Delivery Array (PDA), which known give coded caching schemes with low subpacketization for systems neither security nor privacy constraints. uses superposition keys keys, both cache placement transmitted signal, guarantee privacy, respectively. In particular, among all PDA-based schemes, memory-load pairs achieved PDA describing Maddah-Ali Niesen’s Pareto optimal have lowest subpacketization. Moreover, load-memory tradeoff within constant multiplicative gap, except small memory regime (i.e., when size between 1 2) number smaller than Remarkably, does not worsen compared best that either only regimes or mentioned above.