Practical Known-Plaintext Attacks against Physical Layer Security in Wireless MIMO Systems

Abstract

Physical layer security schemes for wireless communication systems have been broadly studied from an information theory point of view. In contrast, there is a dearth of attack methodologies to analyze the achievable security on the physical layer. To address this issue, we develop a novel attack model for physical layer security schemes, which is the equivalent to known-plaintext attacks in cryptoanalysis. In particular, we concentrate on analyzing the security of orthogonal blinding schemes that disturb an eavesdropper’s signal reception using artificial noise transmission. We discuss the theory underlying our attack methodology and develop an adaptive filter trained by known-plaintext symbols to degrade the secrecy of orthogonal blinding. By means of simulation and measurements on real wireless channels using software-defined radios with OFDM transceivers, we obtain the operating area of our attack and evaluate the achievable secrecy degradation. We are able to reduce the secrecy of orthogonal blinding schemes to Symbol Error Rates (SERs) below 10% at an eavesdropper, with a knowledge of only a 3% of the symbols transmitted in typical WLAN frames.