论文标题
交叉哈希：分散的接触跟踪协议中的匿名遭遇
Cross Hashing: Anonymizing encounters in Decentralised Contact Tracing Protocols
论文作者
论文摘要
在COVID-19（SARS-COV-2）流行期间，接触式追踪是管理该流行病的必要工具。基于应用程序的解决方案已出现用于接触跟踪，包括由Apple和Google设计的协议（受称为DP3T的开源协议的影响）。该协议包含两个有据可查的匿名攻击。首先，当某人被标记为测试阳性并将其钥匙公开时，可以在大型地理区域进行24小时的跟踪。其次，虽然该应用需要最小的接触持续时间才能注册联系人，但该属性没有加密保证。这意味着对手可以扫描蓝牙网络，并回顾性地找到谁被感染。我们提出了一种新颖的“交叉哈希”方法来保证最小的暴露时间。我们进一步减轻了感染者的24小时数据暴露，并减少了使用$ k $ - 匿名的哈希和私人设置交叉点识别用户是否已暴露的计算时间。我们从经验上证明，该修改后的协议可以为现有协议提供类似的效力。
During the COVID-19 (SARS-CoV-2) epidemic, Contact Tracing emerged as an essential tool for managing the epidemic. App-based solutions have emerged for Contact Tracing, including a protocol designed by Apple and Google (influenced by an open-source protocol known as DP3T). This protocol contains two well-documented de-anonymisation attacks. Firstly that when someone is marked as having tested positive and their keys are made public, they can be tracked over a large geographic area for 24 hours at a time. Secondly, whilst the app requires a minimum exposure duration to register a contact, there is no cryptographic guarantee for this property. This means an adversary can scan Bluetooth networks and retrospectively find who is infected. We propose a novel "cross hashing" approach to cryptographically guarantee minimum exposure durations. We further mitigate the 24-hour data exposure of infected individuals and reduce computational time for identifying if a user has been exposed using $k$-Anonymous buckets of hashes and Private Set Intersection. We empirically demonstrate that this modified protocol can offer like-for-like efficacy to the existing protocol.
