Contents I. Motivation
Indoor Positioning Systems (IPS) are becoming increasingly important as they enable location estimation within enclosed spaces where GNSS-based positioning, such as the Global Positioning System (GPS), performs poorly due to signal degradation [1]. IPSs that employ UWB technology are currently in high demand for Industrial Internet of Things (IIoT) applications, particularly in transportation and warehouses [2], [3]. However, these systems can be vulnerable to security threats, especially spoofing attacks. Spoofing attacks in positioning systems are a fundamental problem that can severely impact communication networks and are studied on global and local levels [4]. Simply put, a spoofing attack is the transmission of fake signals that receivers accept as authentic ones [5]. It is widely recognized that even a sophisticated positioning system such as the GPS can be vulnerable to spoofing attacks [6]. An example of a spoofing attack can be seen in Fig. 1. In 2011, Iran “captured” a classified U.S. spy Unmanned Aerial Vehicle (UAV) over its territory, mostly undamaged, using a GPS-spoofing method [7]. The cost of capturing a drone using a spoofing method can be assumed as low as $1000 [8]. Besides UAVs, civil GPS spoofing also poses a danger to manned aircraft, maritime craft, communications systems, banking and finance institutions, and power grid [9]. Recently, spoof-resilient measures have been introduced as part of the European GNSS, Galileo, that enable authenti-cation of the source using a protocol called Timed Efficient Stream Loss-tolerant Authentication (TESLA) [11]–[13]. As the name suggests, the TESLA protocol is an authentication protocol designed exclusively for broadcast settings. When used in navigation, it can enable the authenticity of navigation messages (e.g., messages are trusted to be sent by satellites and unforged) such that breaking it is computationally infeasible. It does so by using cryptographic hash functions and delaying the release of keys for authentication in the channel.
