In the last few years, with the increasing popularity of cloud computing and the availability of mobile smart devices as well as ubiquitous network connections, more and more users are uploading their personal data to remote servers. However, this can lead to significant security breaches, where confidentiality, integrity and authentication are constantly threatened. To overcome these multiple problems, multimedia data must be secured, for example by means of encryption before transmission and storage. In this survey, we look into the issues involved in handling encrypted multimedia data, and more specifically we focus on reversible data hiding in encrypted images (RDHEI). The aim of this survey is to present the birth and evolution of RDHEI methods over the last 12 years. We first highlight different classes and characteristics of RDHEI, then describe representative RDHEI methods. A comparison table is presented to summarize the key features and achievements of each representative RDHEI method considered in this survey. Finally, we share the future outlook of emerging applications and open research topics relevant to RDHEI for the next 12 years and beyond.

在过去的几年中，随着云计算的日益普及和移动智能设备的可用性以及无处不在的网络连接，越来越多的用户将其个人数据上传到远程服务器。但是，这可能会导致严重的安全漏洞，从而不断威胁机密性，完整性和身份验证。为了克服这些多重问题，必须保护多媒体数据，例如在传输和存储之前通过加密的方法。在本次调查中，我们研究了处理加密的多媒体数据时涉及的问题，更具体地说，我们专注于隐藏在加密图像（RDHEI）中的可逆数据。这项调查的目的是介绍RDHEI方法在过去12年中的诞生和发展。我们首先重点介绍RDHEI的不同类别和特征，然后描述代表性的RDHEI方法。提出了一个比较表，以总结本次调查中考虑的每种代表性RDHEI方法的关键特性和成就。最后，我们对未来12年及以后的RDHEI相关的新兴应用程序和开放式研究主题具有共同的未来展望。