Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey

This paper provides a comprehensive review of the domain of physical layer security in multiuser wireless networks. The essential premise of physical-layer security is to enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers without relying on higher-layer encryption. This can be achieved primarily in two ways: without the need for a secret key by intelligently designing transmit coding strategies, or by exploiting the wireless communication medium to develop secret keys over public channels. The survey begins with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security. We then describe the evolution of secure transmission strategies from point-to-point channels to multiple-antenna systems, followed by generalizations to multiuser broadcast, multiple-access, interference, and relay networks. Secret-key generation and establishment protocols based on physical layer mechanisms are subsequently covered. Approaches for secrecy based on channel coding design are then examined, along with a description of inter-disciplinary approaches based on game theory and stochastic geometry. The associated problem of physical-layer message authentication is also introduced briefly. The survey concludes with observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials, 201

802.15.4/ZigBee Analysis and Security: tools for practical exploration of the attack surface

This thesis explores methods and techniques for surveying 802.15.4 and ZigBee wireless networks. The tools developed will aid in reconnaissance attacks against target networks; information gathered during this process will be used to profile a target network and its devices, as well as to pinpoint the geolocation of devices for executing physical attacks against the onboard hardware. Attacks against the PHY and MAC layers of the 802.15.4 standard will be explored as well

Reducing Asymmetry in Countering Unmanned Aerial Systems

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumCurrent Counter Unmanned Aerial Systems (C-UAS) rely heavily on low-efficiency techniques such as broadband radio frequency (RF) jamming and high-intensity lasers. Not only do such techniques come at the cost of second and third order effects—such as collateral jamming risks to operational systems, a large RF footprint, and high energy use—but they also present an asymmetry between threat and response. Many commercial, off-the-shelf UAS devices are inexpensive compared to the C-UAS systems historically under focus in Department of Defense (DoD) acquisition. This work argues for leveling that asymmetry by exploring C-UAS autonomy-on-autonomy options by using cyberattack payload capabilities residing on a UAS. By reducing the attack surface to focus on a particular target, these cyber techniques provide scalpel-edged control to the operator, reducing risk to own systems, RF footprint, and collateral damage.Approved for public release; distribution is unlimited

Secrecy Enhancement in Cooperative Relaying Systems

Cooperative communications is obviously an evolution in wireless networks due to its noticeable advantages such as increasing the coverage as well as combating fading and shadowing effects. However, the broadcast characteristic of a wireless medium which is exploited in cooperative communications leads to a variety of security vulnerabilities. As cooperative communication networks are globally expanded, they expose to security attacks and threats more than ever. Primarily, researchers have focused on upper layers of network architectures to meet the requirements for secure cooperative transmission while the upper-layer security solutions are incapable of combating a number of security threats, e.g., jamming attacks. To address this issue, physical-layer security has been recommended as a complementary solution in the literature. In this thesis, physical layer attacks of the cooperative communication systems are studied, and corresponding security techniques including cooperative jamming, beamforming and diversity approaches are investigated. In addition, a novel security solution for a two-hop decode-and-forward relaying system is presented where the transmitters insert a random phase shift to the modulated data of each hop. The random phase shift is created based on a shared secret among communicating entities. Thus, the injected phase shift confuses the eavesdropper and secrecy capacity improves. Furthermore, a cooperative jamming strategy for multi-hop decode-and-forward relaying systems is presented where multiple non-colluding illegitimate nodes can overhear the communication. The jamming signal is created by the transmitter of each hop while being sent with the primary signal. The jamming signal is known at the intended receiver as it is according to a secret common knowledge between the communicating entities. Hence, artificial noise misleads the eavesdroppers, and decreases their signal-to-noise-ratio. As a result, secrecy capacity of the system is improved. Finally, power allocation among friendly jamming and main signal is proposed to ensure that suggested scheme enhances secrecy