Secure Localization with Hidden and Mobile Base Stations

Authors:
  • SCS. Capkun
    S. Capkun
  • MCM. Cagalj
    M. Cagalj
  • MSM. Srivastava
    M. Srivastava
Publisher website
Google Scholar
Abstract
Until recently, the problem of localization in wireless networks has been mainly studied in a non-adversarial setting. Only recently, a number of solutions have been proposed that aim to detect and prevent attacks on localization systems. In this work, we propose a new approach to secure localization based on hidden and mobile base stations. Our approach enables secure localization with a broad spectrum of localization techniques: ultrasonic or radio, based on received signal strength or signal time of flight. Through several examples we show how this approach can be used to secure node-centric and infrastructure- centric localization schemes. We further show how this approach can be applied to secure localization in sensor networks. I. INTRODUCTION In the last decade, researchers have proposed a number of positioning and ranging techniques for wireless networks (43), (44), (35), (3), (20), (7). The use of these techniques is broad and ranges from enabling networking functions (i.e., position- based routing) to enabling location-related applications (e.g., access control, data harvesting). The proposed techniques were mainly studied in non- adversarial settings. Ranging and positioning techniques are, however, highly vulnerable to attacks from dishonest nodes and external attackers; dishonest nodes can report false po- sition and distance information in order to cheat on their locations; external attackers can spoof measured positions of honest nodes. Positioning and ranging techniques in wireless networks mainly rely on measurements of the times of flight of radio (RF ToF) or ultrasound signals (US ToF), and on the measurements of received strengths of radio signals of devices (RF RSS). An attacker can generally influence all these measurements by jamming and delaying signals, and by modifying their signal strengths. Positioning systems based on ultrasound time of flight (US ToF) and those based on measurements of signal strength of radio signals (RF RSS) are particulary vulnerable to position spoofing attacks. Systems based on radio time of flight measurements are less vulnerable to attacks because of the high speed of signal propagation, Recently, a number of secure positioning techniques were proposed (25), (26), (10), (28), (29) to cope with these prob- lems. These mechanisms rely on GPS, high speed hardware, directional antennas, or on robust statistics. In this paper, we propose a different approach to secure positioning that relies on a set of covert base stations used for secure positioning. By covert base stations (CBS), we mean base stations whose positions are not known to the attacker at the time of the execution of secure positioning. In our system, positions of covert base stations represent a secret input (a key) to the system. Covert base stations can be realized by hiding or disguising static base station or by the random motion of mobile base stations. Typically, covert base stations are passive. We show through three example protocols how covert base stations can be used to secure node-centric and infrastructure- centric positioning, as well as positioning in sensor networks. We discuss how security of the proposed protocols depends on the precision of the positioning and ranging techniques, and on the number of the covert base stations. We capture this analytically.