BeamSec: A Practical mmWave Physical Layer Security Scheme Against Strong Adversaries

TL;DR

BeamSec enhances mmWave physical layer security by encoding information over diverse beam-pairs without needing eavesdropper location, effectively defending against colluding adversaries and improving secrecy rates in standard-compliant systems.

Contribution

Proposes BeamSec, a novel beam-based security scheme for mmWave systems that operates without eavesdropper location knowledge and is compatible with standard hardware.

Findings

Outperforms benchmark schemes against single and colluding eavesdroppers.

Enhances secrecy rate by 79.8% over random beam selection.

Proven compatibility with IEEE 802.11ad/ay standards.

Abstract

The high directionality of millimeter-wave (mmWave) communication systems has proven effective in reducing the attack surface against eavesdropping, thus improving the physical layer security. However, even with highly directional beams, the system is still exposed to eavesdropping against adversaries located within the main lobe. In this paper, we propose \acrshort{BSec}, a solution to protect the users even from adversaries located in the main lobe. The key feature of BeamSec are: (i) Operating without the knowledge of eavesdropper's location/channel; (ii) Robustness against colluding eavesdropping attack and (iii) Standard compatibility, which we prove using experiments via our IEEE 802.11ad/ay-compatible 60 GHz phased-array testbed. Methodologically, BeamSec first identifies uncorrelated and diverse beam-pairs between the transmitter and receiver by analyzing signal characteristics available through standard-compliant procedures. Next, it encodes the information jointly over all selected beam-pairs to minimize information leakage. We study two methods for allocating transmission time among different beams, namely uniform allocation (no knowledge of the wireless channel) and optimal allocation for maximization of the secrecy rate (with partial knowledge of the wireless channel). Our experiments show that \acrshort{BSec} outperforms the benchmark schemes against single and colluding eavesdroppers and enhances the secrecy rate by 79.8% over a random paths selection benchmark.