A major challenge in securing wireless applications and services is the inherent vulnerability of radio transmissions to communication jamming Denial-of-Service (DoS) attacks. This vulnerability gains in significance the more one takes the ubiquity of these applications and services for granted and becomes a crucial factor in the context of safety-critical applications. At best, failures of safety-critical systems can result in substantial financial damage-at worst, in loss of life. In this

more »

... is, we investigate the fundamental primitives that enable jamming-resistant communication and propose novel anti-jamming techniques for scenarios where common anti-jamming techniques cannot be applied. This includes scenarios where network dynamics or lack of trust in the devices prohibits the pre-distribution of shared secrets (a prerequisite for common anti-jamming techniques), or where the use of anti-jamming communication is precluded by the constraints of the employed (e.g., narrowband and single-channel) transceivers. In the first part of this thesis, we tackle the problem of how devices that do not share any secrets can establish a jamming-resistant communication over a wireless radio channel in the presence of a communication jammer. We address the dependency between anti-jamming spread-spectrum communication and pre-shared keys that is inherent to this problem, and propose Uncoordinated Frequency Hopping (UFH), a novel anti-jamming technique, as a solution to break this dependency. We present and evaluate several UFH-based communication schemes and show their feasibility by means of a prototype implementation. In particular, we illustrate how UFH enables the jamming-resistant execution of (group) key agreement protocols in order to bootstrap common (coordinated) frequency hopping. In the second part of this thesis, we study the problem of jamming attacks on alarm forwarding in (security-and safety-critical) wireless sensor networks. We argue that common anti-jamming techniques are beyond the capabilities of current sensor nodes and demonstrate the vulnerability to jamming of current forwarding schemes. Prompted by this deficiency, we discuss alternative jamming mitigation techniques and present a novel jamming detection scheme to counter advanced (reactive single bit) jamming attacks. We perform a detailed evaluation of the proposed schemes and validate our findings experimentally. The results show that our solution effectively detects sophisticated jamming attacks and enables the formation of robust sensor networks for the dependable delivery of alarms messages.