Towards Secure and Scalable UWB-based Positioning Systems

Positioning systems based on ultra-wideband (UWB) technology are becoming ubiquitous and enable a plethora of attractive Internet of Things applications, ranging from smart access and asset tracking to the navigation of autonomous vehicles. As these positioning systems are often deployed over large areas, the focus of UWB-based research has recently shifted to the development of scalable solutions that can offer a high positioning accuracy for countless tags while maximizing energyefficiency. At the same time, as positioning systems are increasingly used in safety-critical settings, several academic efforts and the standardization activities of the IEEE $802. 15.4 z$ working group have laid the foundations for a secure distance estimation using UWB technology. Unfortunately, these two endeavours have followed independent tracks that do not blend together. In this paper, we highlight this issue and describe the challenge of securing modern UWB-based positioning systems that are designed with scalability in mind. We first illustrate how the use of unidirectional communications, the need for synchronized anchors, and the use of quasi-simultaneous responses, which are common features of recent scalable UWB systems based on timedifference-of-arrival, make these solutions vulnerable to several attacks, despite the use of IEEE $802. 15.4 z$. After carrying out a security analysis and describing how scalable UWB systems are exposed to several attacks, we devise a number of design concepts to counteract the identified attacks and secure these systems.