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.

翻译：在内容分发网络（CDN）中，向用户提供数字内容时，高峰时段资源紧张，而非高峰时段资源利用率不足。缓存技术有助于平衡这一矛盾。在非高峰时段，部分内容被分发至用户本地缓存；高峰时段则利用缓存数据响应用户请求，通过减少热门内容的重复传输来缓解网络压力。在\emph{编码缓存}中，缓存内容放置策略与传输技术协同设计以优化网络吞吐量。由于信息传播与娱乐内容分发均依赖CDN，缓存放置、用户需求及内容传输的安全性与隐私性至关重要。现有\emph{安全编码缓存}研究大多在注重效率的解决方案上叠加安全机制，且多数方案仅关注流程中孤立环节的安全性。统一网络模型的缺失也导致方案难以比较或融合。本综述系统分析了安全编码缓存的安全与隐私需求，从安全性能与安全成本两个维度评估现有方案，同时梳理了实现安全编码缓存的技术路径及其局限性。此外，本文将安全编码缓存置于其他安全内容分发原语的宏观背景下进行探讨，进而识别并排序未来亟待解决的安全与隐私挑战。