Exploiting the physical layer for enhanced security [Security and Privacy in Emerging Wireless Networks]

While conventional cryptographic security mechanisms are essential to the overall problem of securing wireless networks, they do not directly leverage the unique properties of the wireless domain to address security threats. The wireless medium is a powerful source of domain-specific information that can complement and enhance traditional security mechanisms. In this article we argue that new security paradigms which exploit physical layer properties of the wireless medium, such as the rapid spatial, spectral, and temporal decorrelation properties of the radio channel, can enhance confidentiality and authentication services. We outline some basic constructions for these services, and then provide a case study for how such strategies can be integrated into a broader security framework for a wireless network.

Introduction

Most of the focus of cross-layer optimization in wireless networks has been on enhancing basic network operations, such as routing and medium access control, and little attention has been devoted to using cross-layer information to enhance security. This is somewhat surprising, given that wireless networks have properties that make them markedly less secure than their wired counterparts. Perhaps foremost of these is the fact that the wireless medium is intrinsically a broadcast medium. In order for an adversary to overhear communications in the wired world, a physical connection to the wire is required. In contrast, for wireless networks, adversaries can easily witness anything that is transmitted as long as they are within listening range of the transmitter. Further complicating matters are the ubiquity and portability of the platform itself, implying that adversaries can attempt to access the network from anywhere. This fact is evidenced by extensive underground wardriving efforts, and the end result is that network intrusion and subversion is now easier.