The coronavirus pandemic is a new reality, and it severely affects the modus vivendi of the international community. In this context, governments are rushing to devise or embrace novel surveillance mechanisms and monitoring systems to fight the outbreak. The development of digital tracing apps, which among others are aimed at automatising and globalising the prompt alerting of individuals at risk in a privacy-preserving manner, is a prominent example of this ongoing effort. Very promptly, a number of digital contact tracing architectures have been sprouted, followed by relevant app implementations adopted by governments worldwide. Bluetooth, specifically its Low Energy (BLE) power-conserving variant, has emerged as the most promising short-range wireless network technology to implement the contact tracing service. This work offers the first to our knowledge full-fledged review of the most concrete contact tracing architectures proposed so far in a global scale. This endeavour does not only embrace the diverse types of architectures and systems, namely, centralised, decentralised, or hybrid, but also equally addresses the client side, i.e., the apps that have been already deployed in Europe by each country. There is also a full-spectrum adversary model section, which does not only amalgamate the previous work in the topic but also brings new insights and angles to contemplate upon.

中文翻译：

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揭开COVID-19数字联系追踪的神秘面纱：框架和移动应用程序调查

冠状病毒大流行是一个新的现实，严重影响了国际社会的生存方式。在这种情况下，政府急于设计或采用新颖的监视机制和监视系统以抗击疫情。数字跟踪应用程序的开发（其中包括旨在以隐私保护的方式自动化和全球化对处于危险中的个人的迅速警报）是这种持续努力的一个突出示例。很快，就出现了许多数字联系人跟踪体系结构，随后全球各国政府采用了相关的应用程序实现。蓝牙，特别是其低功耗（BLE）节能型，已成为实现联系人跟踪服务的最有希望的短程无线网络技术。这项工作为我们提供了迄今为止对全球范围内提出的最具体的联系人跟踪体系结构的全面回顾。这项工作不仅包含各种类型的体系结构和系统，即集中式，分散式或混合式，而且还平等地面向客户端，即每个国家/地区已经在欧洲部署的应用程序。还有一个全谱的对抗模型部分，它不仅融合了该主题中以前的工作，而且带来了新的见解和思考的角度。而且也同样面向客户端，即每个国家/地区已经在欧洲部署的应用程序。还有一个全谱的对抗模型部分，它不仅融合了该主题中以前的工作，而且带来了新的见解和思考的角度。而且也同样面向客户端，即每个国家/地区已经在欧洲部署的应用程序。还有一个全谱的对抗模型部分，它不仅融合了该主题中以前的工作，而且带来了新的见解和思考的角度。