Master Theses and Student Projects

FPGA Implementation of UWB Impulse Radio Based Distance Bounding

Today's communication systems are often vulnerable to wormhole or relaying attacks, leading to severe security problems. Distance Bounding (DB) protocols are authentication protocols designed to protect against these attacks. They determine an upper bound on the physical distance between two communication parties the verifier V (e.g. a door requiring an access key) and the prover P (e.g. a wireless key device). UWB technology promises an innovative wireless implementation of DB protocols, using low cost components. A crucial aspect for DB algorithms, besides a high temporal resolution, is the processing delay of P between receiving a challenge from V and transmitting the answer to V. Even current UWB transceivers may add a considerable processing delay, which decreases the provided security. The goal of this student project is to implement and analyze a novel UWB transceiver architecture, which is able to both detect incoming UWB pulses and transmit answers with minimal delay.

Fig. 1     Security systems become wireless, e.g. access control, airport security etc.

With proliferation of wireless communication to security related systems, design and analysis of security protocols are essential. Considering for example access control to buildings, it is desirable to use a low-complexity wireless device working as a key. The door, here referred to as the verifier V and the key (prover P) share a secret, which legitimates an authorized person to enter. The aforementioned relay or wormhole attack makes the system vulnerable. The attacker A establishes communication between V and a distant P₂ by forwarding the respective messages (see Fig. 2). Using this attack, the attacker can open the door without having to decrypt messages or guessing the shared key. Distance bounding protects against these attacks as follows: An authorized P is only allowed to open the door if it proves to be not further from V than a certain maximum distance d_max by replying to several single bit challenges.

Fig. 2     Wormhole attack	Fig. 3     System Model: Verifier and Prover

The high bandwidth of UWB enables time-of-arrival measurements with high resolution. Moreover, UWB impulse radio enables the implementation of low complexity and low power transceivers. In particular, noncoherent receivers can be implemented very efficiently. Recently, we presented an energy detection (ED) based ultra-low power UWB system design with an overall estimated current consumption of less than 1 mW. The feasibility of the presented design respecting FCC power limits together with transmission of only one pulse per bit (very important for the DB approach) has been shown by means of computer simulation and over the air. This makes an UWB impulse radio (IR) design based on the ED a very promising candidate for the implementation of DB protocols. The resulting transceiver of P would combine low complexity and low power consumption with fast response/low delay that is essential for DB hardware. The next step in the development towards the realization of a distance bounding systems contains prototyping on chip level. In cooperation with the Systems Security Group, an FPGA-based transceiver shall be implemented to analyze and demonstrate the performance of UWB impulse radio based DB.

For further information please contact Heinrich Luecken.

[1] M. Kuhn, H. Luecken, and N. O. Tippenhauer, "UWB Impulse Radio Based Distance Bounding," 7th Workshop on Positioning, Navigation and Communication 2010 (WPNC'10), Dresden, Germany, Mar. 2010.