Path loss prediction for electromagnetic side-channel signals

This paper investigates propagation mechanisms that EM side-channel signals experience at different frequencies and proposes models for near-field and far-field propagation of side-channel signals. The near-field propagation is modelled as a field created by an electric monopole (Hertzian dipole) and a magnetic dipole, where the received power is collected using only magnetic components of the EM field. This model resulted in excellent match with measured data. Furthermore, this paper investigates unintentionally modulated side-channel signals. The propagation of EM side-channel signals was modelled using free-space propagation model which resulted in excellent match with measured data. In both cases we have observed that signal can be received at several meters from the side-channel source. The proposed models are the first step in understanding propagation mechanisms of EM side-channel signals and how to predict the distance at which they can be received.