Device-to-Device Secure Coded Caching

TL;DR

This paper introduces secure device-to-device coded caching schemes that ensure confidentiality of files during storage and delivery, leveraging secret sharing and one-time pads, with proven bounds and effectiveness demonstrated through numerical analysis.

Contribution

It develops centralized and decentralized secure coded caching schemes with information-theoretic guarantees, optimizing cache placement and delivery without prior knowledge of active users.

Findings

Achieves upper bounds on minimum delivery rate with security guarantees.

Lower bounds indicate a vanishing gap as cache size increases.

Secure D2D caching is effective against external eavesdroppers.

Abstract

This paper studies device to device (D2D) coded-caching with information theoretic security guarantees. A broadcast network consisting of a server, which has a library of files, and end users equipped with cache memories, is considered. Information theoretic security guarantees for confidentiality are imposed upon the files. The server populates the end user caches, after which D2D communications enable the delivery of the requested files. Accordingly, we require that a user must not have access to files it did not request, i.e., secure caching. First, a centralized coded caching scheme is provided by jointly optimizing the cache placement and delivery policies. Next, a decentralized coded caching scheme is developed that does not require the knowledge of the number of active users during the caching phase. Both schemes utilize non-perfect secret sharing and one-time pad keying, to guarantee secure caching. Furthermore, the proposed schemes provide secure delivery as a side benefit, i.e., any external entity which overhears the transmitted signals during the delivery phase cannot obtain any information about the database files. The proposed schemes provide the achievable upper bound on the minimum delivery sum rate. Lower bounds on the required transmission sum rate are also derived using cut-set arguments indicating the multiplicative gap between the lower and upper bounds. Numerical results indicate that the gap vanishes with increasing memory size. Overall, the work demonstrates the effectiveness of D2D communications in cache-aided systems even when confidentiality constraints are imposed at the participating nodes and against external eavesdroppers.