On non‐destructive detection of hidden passive radio‐frequency eavesdroppers

Abstract

This paper investigates the possibility of detecting the presence of hidden radio-frequency eavesdroppers embedded in modern electronic devices. The detection of such cyber security threats is quite difficult as they intercept wireless signals passively and never transmit them. The proposed detection approach relies on the fact that the impedance of active radio-frequency components in the eavesdropper circuit depends on their biased voltage, and that scattering characteristics of the eavesdropper can be affected by its internal impedance change. Using the device under test as a reflector, scattering characteristics and channel state information are measured. By comparing channel state information differences for the device under test in different power supply states, the presence of hidden eavesdroppers can be identified. Full-wave numerical simulations are performed to verify the effectiveness of the proposed method. As a non-destructive testing approach, the proposed method exhibits a robust and easy way to detect hidden eavesdroppers.