On Coded Caching With Private Demands

Caching is an efficient way to reduce network traffic congestion during peak hours by storing some content at the user's local cache memory without knowledge of later demands. For shared-link caching model, Maddah-Ali and Niesen (MAN) proposed a two-phase (placement delivery) coded strategy, which order optimal within constant factor. However, in MAN scheme, each user can obtain information about demands other users, i.e., scheme inherently prone tampering spying activity/demands users. In this paper, we formulate information-theoretic model with private demands, where there are K cache-aided users (which up M files) connected central server access N files. Each requests L Our objective design minimum load while preserving privacy respect A trivial solution uncoded lets recover all files, referred as baseline scheme. problem propose two novel schemes achieve users' also achieving non-trivial gain over The general underlying idea satisfy generating set multicast messages that symmetric library such for k, mutual between these given demand k zero. first virtual-user introduce number virtual L-subset files demanded real or (effective) use delivery generate messages. From viewpoint user, even if single message not. This incurs extremely large sub-packetization. Then, second MDS-based based on MDS-coded placement. case, contains one symbol from file thus again user. sub-packetization level exponentially smaller than needed Compared existing converse bounds privacy, proved be factor when ? LK, ? LK N/K. addition, N/2, both 2.