Sidharth Jaggi (The Chinese University of Hong Kong)
Covert communication considers the following problem -- if Alice wishes
towhisper to Bob while ensuring that the eavesdropper Eve cannot even detect
whether or not Alice is whispering, how much can she whisper. Ensuring such a
stringent security requirement can be met requires new ideas from information
theory, coding theory, and cryptography. In this talk I will survey the state of the
existing literature (recent information-theoretic capacity-style results for a variety
of settings), and then discuss even more recent results. Specifically, I will
Code constructions: Computationally efficient code constructions that achieve
the information-theoretic capacity bounds.
Resilience to jamming: In some settings, Eve may not just be a passive
eavesdropper, but actively attempt to jam Alice's communication, even if she isn't sure whether or not Alice is actually whispering. I will discuss covert
communication schemes that are resilient to such malicious jamming.
Impact of environmental uncertainty: Often, noise levels on the communication
medium are not static, but stochastically varying (for instance,
infading channels). It turns out such natural variation can dramatically impact the
capacity -- indeed, in general such variation hurts Eve's detector much more thanit hurts Bob's decoder.