Séminaire ETIS-ICI – Laura Luzzi

Title: Covert communication over additive noise channels

(based on joint work with Cécile Bouette, Ligong Wang and Matthieu Bloch)

Abstract: In the first part of the talk, I will give a brief overview of my research in the areas of physical layer security and post-quantum cryptography.
Then, I will focus on some recent results in the setting of covert communication in physical layer security. In this scenario, a transmitter and a receiver wish to communicate reliably while preventing an eavesdropper from detecting the fact that a communication is ongoing. It is known that the channel capacity under this constraint is zero, and the amount of information that can be sent reliably and covertly scales like the square root of the number of channel uses. We study the scaling constant of the square root law, or “covert capacity”, for a general class of memoryless additive noise channels, and show that it is upper bounded by the square root of the varentropy of the noise. Under some additional assumptions, we show that this upper bound is tight.
In the last part of the talk, we consider the asymptotic limits of covert communication over an i.i.d. Gaussian channel when we allow a positive average error probability ε. In this case, the strong converse does not hold, and the scaling constant C_ε depends on ε. We derive upper and lower bounds for C_ε and show that allowing a small positive error probability enables the transmission of additional covert information.

Bio: Laura Luzzi is an Associate Professor (MCF HDR) at ENSEA, Cergy-Pontoise, France, and a researcher at ETIS (UMR 8051, CY Cergy Paris Université, ENSEA, CNRS). She is currently a visiting researcher with Project COSMIQ, Centre Inria de Paris. Her research interests include physical layer security and post-quantum cryptography.