A systematic review of secure coded caching

In a content delivery network (CDN), resources are strained during peak-time and underutilised in off-peak times when supplying digital content to users. Caching can help balance this. At the off-peak time some content is delivered to users’ local caches. During peak time, the use of cached data to serve users’ requests relieves strain on the network by reducing repeated transfer of popular content. In \emph{coded caching}, the cache content placement is designed in conjunction with the delivery techniques to optimise network throughput. Since dissemination of information, as well as the delivery of entertainment, is reliant on CDNs, the security and privacy of cache placement, user demand, and content delivery, are paramount. In much of the literature in \emph{secure coded caching}, security is built on top of solutions that have efficiency in mind, and most current proposals focus on the security of individual parts of the process. A lack of a unifying network model also makes it difficult to compare or combine solutions. In this survey we analyse the security and privacy requirements of secure coded caching, and evaluate existing schemes in terms of the security provided and the cost of this security provision. We also review the techniques used to achieve secure coded caching and analyse their limitations. In addition, we contextualise secure coded caching in the landscape of other secure content delivery primitives. As a result, we identify and prioritise open security and privacy challenges for the future.

💡 Research Summary

The manuscript presents a comprehensive systematic review of secure coded caching, a technique that combines the bandwidth‑saving benefits of coded caching with confidentiality, request privacy, and cache integrity guarantees. After introducing the classic Maddah‑Ali–Niesen model—where a central server stores N files, each user has a cache of size M files, and during the delivery phase the server broadcasts a single coded message to satisfy all K users—the authors discuss the underlying assumptions of this model (offline placement without bandwidth limits, isolated caches, error‑free shared broadcast link). They argue that these assumptions are overly idealized for real‑world CDN and edge‑computing deployments, especially when security considerations are introduced.

The paper categorises security requirements into three primary dimensions: (1) file confidentiality against eavesdroppers and unauthorized users, (2) request privacy so that neither the server nor other users can infer which file a user requested, and (3) cache integrity/anti‑poisoning to prevent tampering or malicious cache poisoning attacks. Existing literature is surveyed and classified according to which of these properties they address. For example, Sengupta et al. achieve confidentiality by splitting each file into secret‑shared pieces and transmitting linear combinations; Ravindrakumar et al. protect request privacy through random request mapping and broadcasting a common coded message; Gururapadhye et al. enforce cache integrity using hash‑based authentication, albeit at the cost of high sub‑packetisation and additional communication overhead.

The authors also compare secure coded caching with related secure content‑delivery primitives such as information‑centric networking (ICN) name‑based encryption, edge‑computing federated‑learning noise injection, and multicast authentication schemes. While these approaches offer useful techniques, they often suffer from complex key‑management, significant throughput penalties, or narrow attack‑model coverage, limiting their direct applicability to coded caching scenarios.

Key limitations identified in the current body of work include: (i) the prevalent assumption of a one‑time, static cache placement, which undermines security when caches are updated dynamically; (ii) security mechanisms that substantially increase the delivery rate R, eroding the primary efficiency advantage of coded caching; (iii) narrow adversarial models that omit realistic threats such as DDoS, cache‑poisoning, insider servers, and colluding users; and (iv) the lack of concrete, scalable key‑distribution frameworks for large‑scale CDN deployments.

To address these gaps, the paper outlines several research directions. First, the design of security‑aware protocols that support dynamic cache updates while preserving confidentiality and integrity, possibly through lightweight secret‑sharing or homomorphic encryption techniques. Second, the development of hybrid coding‑encryption schemes that minimize the security overhead and keep the delivery rate close to the optimal uncoded bound; examples include linear‑algebra‑based secret sharing combined with low‑complexity authentication codes. Third, the formulation of cooperative security models for multi‑server, multi‑cache environments, integrating trust transitivity, real‑time attack detection, and adaptive mitigation strategies. Finally, the authors call for rigorous, standardized threat models and practical key‑management solutions tailored to CDN scale.

In summary, the review highlights that secure coded caching remains an emerging field with fragmented solutions that often treat security as an afterthought. By systematically classifying existing schemes, exposing their assumptions, and pinpointing open challenges, the paper provides a clear roadmap for future work aimed at achieving truly secure and efficient content delivery in modern network infrastructures.