The outbreak of coronavirus 2019 (Covid-19) has imposed a worldwide lockdown, changing the way people live and work, and pressuring the healthcare systems in many countries. Contact tracing based on smartphone apps (app-based contact tracing) has emerged as a possible solution to trace contagions and enforce more sustainable and selective quarantines. However, these apps require a very high adoption rate to reach the critical mass for effective contact tracing. As an alternative, network-based contact tracing, which exploits geo-localization in next generation networks (e.g., 5G) can be used by mobile operators (MOs) to passively trace users' mobility and contacts, provided that a targeted localization accuracy of down to one meter can be achieved. To effectively trace contagions, the identities of positive individuals, which are known by governmental authorities (GAs), are also required. Hence, in network-based contact tracing, MOs and GAs must exchange users' privacy-sensitive data, as geo-locations and infection status, to compute the likelihood that an individual has been infected. To address the privacy issues raised by network contact tracing, after presenting an overview of app-based vs. network-based contact tracing systems, we propose a protocol to make network-based systems compliant with stringent privacy requirements. From extensive simulations, we observe that the cost to guarantee privacy (evaluated in terms of data overhead introduced by the protocol) is acceptable. Finally, we elaborate on the advantages of the proposed system (e.g., more efficient monitoring of virus spread), as well as on the open issues that should be solved before its adoption (e.g., extensive research on potential privacy leakage is required).

中文翻译：

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基于网络的接触者追踪用于检测 Covid-19 传染：一种保护隐私的方法


2019 年冠状病毒 (Covid-19) 的爆发在全球范围内实施了封锁，改变了人们的生活和工作方式，并给许多国家的医疗保健系统带来了压力。基于智能手机应用程序的接触者追踪（基于应用程序的接触者追踪）已成为追踪传染病和实施更可持续和选择性隔离的可能解决方案。然而，这些应用程序需要非常高的采用率才能达到有效接触者追踪的临界质量。作为替代方案，移动运营商 (MO) 可以使用基于网络的联系人追踪（利用下一代网络（例如 5G）中的地理定位）来被动追踪用户的移动性和联系人，前提是目标定位精度为可以达到一米。为了有效追踪传染病，还需要政府当局 (GA) 知道的阳性个体的身份。因此，在基于网络的接触者追踪中，MO 和 GA 必须交换用户的隐私敏感数据（例如地理位置和感染状态），以计算个人被感染的可能性。为了解决网络联系人追踪带来的隐私问题，在概述基于应用程序与基于网络的联系人追踪系统之后，我们提出了一种协议，使基于网络的系统符合严格的隐私要求。从广泛的模拟中，我们观察到保证隐私的成本（根据协议引入的数据开销来评估）是可以接受的。最后，我们详细阐述了所提出的系统的优点（例如，更有效地监控病毒传播），以及在采用该系统之前应解决的开放问题（例如，需要对潜在的隐私泄露进行广泛的研究）。