Spread Spectrum and Jamming for Wireless Secrecy

Abstract

As Wireless Networks become increasingly popular, security is turning out to be something of the utmost importance to guarantee the confidentiality and robustness of communication under these systems. This thesis focuses on using physical-layer mechanisms to enhance confidentiality against eavesdroppers, more specifically, a recently published tweaked version of Frequency-Hopping - Uncoordinated Frequency Hopping - with the incorporation of defensive jammers for added security. For that, we characterize the secrecy level of this spread spectrum scheme, by devising a mathematical framework to assess the secure throughput (probability of secure communication) of devices operating under Uncoordinated Frequency Hopping. We then extend this mathematical model to accommodate the impact of defensive jammers and propagation effects on the legitimate communication, as well as, implement and evaluate this technique in a real-world test-bed. Results show that by exploiting frequency diversity, this method may be used for secret key-establishment, notably when eavesdroppers may appear in advantageous locations. Adding defensive jamming is also shown to be an effective solution for boosting the secrecy level against non-detectable adversaries like eavesdroppers.