Covert Communication Over Noisy Channels: A Resolvability Perspective

By Matthieu R. Bloch. IEEE Transactions on Information Theory, 2015

396 citations recorded by the source corpus.

We consider the situation in which a transmitter attempts to communicate reliably over a discrete memoryless channel, while simultaneously ensuring covertness (low probability of detection) with respect to a warden, who observes the signals through another discrete memoryless channel. We develop a coding scheme based on the principle of channel resolvability, which generalizes and extends prior work in several directions. First, it shows that irrespective of the quality of the channels, it is possible to communicate on the order of √n reliable and covert bits over n channel uses if the transmitter and the receiver share on the order of √n key bits. This improves upon earlier results requiring on the order of √n log n key bits. Second, it proves that if the receiver's channel is better than the warden's channel in a sense that we make precise, it is possible to communicate on the order of √n reliable and covert bits over n channel uses without a secret key. This generalizes earlier results established for binary symmetric channels. We also identify the fundamental limits of covert and secret communications in terms of the optimal asymptotic scaling of the message size and key size, and we extend the analysis to Gaussian channels. The main technical problem that we address is how to develop concentration inequalities for low-weight sequences. The crux of our approach is to define suitably modified typical sets that are amenable to concentration inequalities.

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Citations in the corpus

Semantic Communications for Future Internet: Fundamentals, Applications, and Challenges (2022, unknown): “Considering the success of covert communication [212], we can make the data eavesdropper unsure whether the SemCom is ongoing by introduced interference to the physical layer for secure wireless transmission.”
Covert Communications: A Comprehensive Survey (2023, background): “After the initial work mentioned above, plenty of research related to covert limits is further conducted [97], [129], [130], [131], [132], [133], [134], [135].”
Covert Communication in the Presence of an Uninformed Jammer (2016, background): “Follow-on work has considered the length of the pre-shared secret in [4] and [5], characterization of the constant hidden by Big-O notation in [5] and [6], and both the theory and experimental verification of covert communication over quantum channels in [7] and [8].”
Fundamental Limits of Communication With Low Probability of Detection (2015, background): “If input symbol 0 is redundant, then for any δ ≥ 0, lim ↓0 lim n→∞ Kn(δ, ) n = max I(P,W ), (6) where the maximum is taken over input distribution P that satisfies (5).”
Low Probability of Detection Communication: Opportunities and Challenges (2019, background): “The ﬁrst category focuses characterizing the performance limits of LPD communication (e.g., [5]), which aims to disclose the number of information bits that can be conveyed with a negligible detection probability.”