Desilo Inc, Seoul, Republic of Korea.
Department of Industrial Engineering, Seoul National University, Seoul, Republic of Korea.
J Med Internet Res. 2021 Jul 12;23(7):e26371. doi: 10.2196/26371.
Various techniques are used to support contact tracing, which has been shown to be highly effective against the COVID-19 pandemic. To apply the technology, either quarantine authorities should provide the location history of patients with COVID-19, or all users should provide their own location history. This inevitably exposes either the patient's location history or the personal location history of other users. Thus, a privacy issue arises where the public good (via information release) comes in conflict with privacy exposure risks.
The objective of this study is to develop an effective contact tracing system that does not expose the location information of the patient with COVID-19 to other users of the system, or the location information of the users to the quarantine authorities.
We propose a new protocol called PRivacy Oriented Technique for Epidemic Contact Tracing (PROTECT) that securely shares location information of patients with users by using the Brakerski/Fan-Vercauteren homomorphic encryption scheme, along with a new, secure proximity computation method.
We developed a mobile app for the end-user and a web service for the quarantine authorities by applying the proposed method, and we verified their effectiveness. The proposed app and web service compute the existence of intersections between the encrypted location history of patients with COVID-19 released by the quarantine authorities and that of the user saved on the user's local device. We also found that this contact tracing smartphone app can identify whether the user has been in contact with such patients within a reasonable time.
This newly developed method for contact tracing shares location information by using homomorphic encryption, without exposing the location information of patients with COVID-19 and other users. Homomorphic encryption is challenging to apply to practical issues despite its high security value. In this study, however, we have designed a system using the Brakerski/Fan-Vercauteren scheme that is applicable to a reasonable size and developed it to an operable format. The developed app and web service can help contact tracing for not only the COVID-19 pandemic but also other epidemics.
为了支持接触者追踪，已经采用了各种技术，事实证明这些技术对控制 COVID-19 大流行非常有效。应用该技术，隔离当局要么提供 COVID-19 患者的位置历史记录，要么所有用户都提供自己的位置历史记录。这不可避免地会暴露患者的位置历史记录或其他用户的个人位置历史记录。因此，就出现了一个隐私问题，公共利益（通过信息发布）与隐私暴露风险之间存在冲突。
本研究旨在开发一种有效的接触者追踪系统，该系统不会向系统中的其他 COVID-19 患者用户或用户向隔离当局公开患者的位置信息。
我们提出了一种名为 PROTECT（用于传染病接触追踪的隐私导向技术）的新协议，该协议使用 Brakerski/Fan-Vercauteren 同态加密方案安全地共享患者的位置信息，并使用新的安全邻近计算方法。
我们通过应用所提出的方法开发了一个面向最终用户的移动应用程序和一个面向隔离当局的网络服务，并验证了它们的有效性。所提出的应用程序和网络服务计算由隔离当局发布的 COVID-19 患者的加密位置历史记录与用户在本地设备上保存的位置历史记录之间的交集。我们还发现，这种接触追踪智能手机应用程序可以在合理的时间内识别用户是否与这些患者接触过。
这种新开发的接触者追踪方法通过同态加密共享位置信息，而不会公开 COVID-19 患者和其他用户的位置信息。尽管同态加密具有很高的安全价值，但在实际问题中应用起来具有挑战性。然而，在本研究中，我们使用 Brakerski/Fan-Vercauteren 方案设计了一个适用于合理规模的系统，并将其开发为可操作的格式。所开发的应用程序和网络服务不仅可用于 COVID-19 大流行，还可用于其他传染病的接触追踪。
