Séminaire ICI : Matthieu Bloch

Titre du séminaire et orateur

Covert communications over noisy channels: information theoretic limits and algorithms.

Matthieu Bloch, Associate Professor in the School of Electrical and Computer Engineering

Date et lieu

mardi 13 juin 2017, 11h.

ENSEA, salle 384


The benefits offered by ubiquitous communication networks are now mitigated by the relative ease with which malicious users can interfere or tamper with sensitive data. The past decade has thus witnessed a growing concern for the issues of privacy, confidentiality, and integrity of communications. In particular, the users in a communication network now often find themselves in a position in which they wish to communicate without being detected by others.

In this talk, we will discuss several results regarding information theoretic covert communications over noisy channels. Unlike traditional problems in physical-layer security and information-theroetic security,the objective here is not to maintain the confidentiality of messages but rather to make the signals provably undetectable against an adversary with unlimited computational power. Intuitively,covert communications are possible if the distribution of the signals perceived by an adversary are indistinguishable from the distribution expected in the absence of communication. The key conceptual idea underlying our approach is to formalize this idea by leveraging the notion of channel resolvability, which is a canonical information-theoretic problem consisting in exploiting error-control codes to shape the distribution of stochastic processes at the output of a noisy channel. This conceptual approach allows us to not only characterize the first and second-order asymptotic limits of covert communication over point-to-point noisy channels, but also identify the limits for several multi-user channel models. Furthermore, the approach suggests a methodology for code design, which we have exploited to develop preliminary low-complexity codes with guaranteed covertness.


Matthieu Bloch is an Associate Professor in the School of Electrical and Computer Engineering. He received the Engineering degree from Supélec, Gif-sur-Yvette, France, the M.S. degree in Electrical Engineering from the Georgia Institute of Technology,Atlanta, in 2003, the Ph.D. degree in Engineering Science from the Université de Franche-Comté, Besançon, France, in 2006, and the Ph.D.degree in Electrical Engineering from the Georgia Institute of Technology in 2008. In 2008-2009, he was a postdoctoral research associate at the University of Notre Dame, South Bend, IN. Since July 2009, Dr. Bloch has been on the faculty of the School of Electrical and Computer Engineering. His research interests are in the areas of information theory, error-control coding, wireless communications, and cryptography. Dr. Bloch is a senior member of the IEEE and has served on the organizing committee of several international conferences; he was the chair of the Online Committee of the IEEE Information Theory Society from 2011 to 2014, he has been on the Board of Governors of the IEEE Information Theory Society since January 2016, and he has been an Associate Editor for the IEEE Transactions on Information Theory since August 2016. He is the co-recipient of the IEEE Communications Society and IEEE Information Theory Society 2011 Joint Paper Award and the co-author of the textbook Physical-Layer Security: From Information Theory to Security Engineering published by Cambridge University Press.