# Information Bytes

Matthieu Bloch
School of Electrical and Computer Engineering
Georgia Institute of Technology

# Recent works

1. M. Tahmasbi and M. R. Bloch, “Covert Secret Key Generation with an Active Warden,” IEEE Transactions on Information Forensics and Security, vol. 15, pp. 1026–1039, Jun. 2020.

We investigate the problem of covert and secret key generation over a state-dependent discrete memoryless channel with one-way public discussion in which an adversary, the warden, may arbitrarily choose the channel state. We develop an adaptive protocol that, under conditions that we explicitly specify, not only allows the transmitter and the legitimate receiver to exchange a secret key but also conceals from the active warden whether the protocol is being run. When specialized to passive adversaries that do not control the channel state, we partially characterize the covert secret key capacity. In particular, the covert secret key capacity is sometimes equal to the covert capacity of the channel, so that secrecy comes “for free.”

@article{Tahmasbi2019,
author = {Tahmasbi, Mehrdad and Bloch, Matthieu R},
title = {Covert Secret Key Generation with an Active Warden},
journal = {IEEE Transactions on Information Forensics and Security},
year = {2020},
volume = {15},
pages = {1026-1039},
month = jun,
doi = {10.1109/TIFS.2019.2932906},
eprint = {1901.02044},
file = {:2020-Tahmasbi-IEEETransIFS.pdf:PDF},
groups = {Steganography and covert communications},
howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}}
}


2. E. Shipilova, M. Barret, M. Bloch, J.-L. Boelle, and J.-L. Collette, “Simultaneous seismic sources separation based on Matrioshka Orthogonal Matching Pursuit, Application in Oil and Gas Exploration,” IEEE Transactions on Geoscience and Remote Sensing, pp. 1–18, Jan. 2020.

@article{Shipilova2019,
author = {Shipilova, Ekaterina and Barret, Michel and Bloch, Matthieu and Boelle, Jean-Luc and Collette, Jean-Luc},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
title = {Simultaneous seismic sources separation based on Matrioshka Orthogonal Matching Pursuit, Application in Oil and Gas Exploration},
year = {2020},
month = jan,
pages = {1 - 18},
doi = {10.1109/TGRS.2019.2959650},
howpublished = {accepted to \emph{IEEE Transactions on Geoscience and Remote Sensing}}
}


3. E. Zhang, M. Bloch, M. Bakshi, and S. Jaggi, “Undetectable Radios: Covert Communication under Spectral Mask Constraints.” submitted to IEEE Transactions on Information Theory, Dec. 2019.

@misc{Zhang2019b,
author = {Zhang, Eric and Bloch, Matthieu and Bakshi, Mayank and Jaggi, Siddarth},
howpublished = {submitted to \emph{IEEE Transactions on Information Theory}},
month = dec,
year = {2019}
}


4. M. Tahmasbi, A. Savard, and M. R. Bloch, “Covert Capacity of Non-Coherent Rayleigh-Fading Channels.” accepted to IEEE Transactions on Information Theory, Nov. 2019.

The covert capacity is characterized for a non-coherent fast Rayleigh-fading wireless channel, in which a legitimate user wishes to communicate reliably with a legitimate receiver while escaping detection from a warden. It is shown that the covert capacity is achieved with an amplitude-constrained input distribution that consists of a finite number of mass points including one at zero and numerically tractable bounds are provided. It is also conjectured that distributions with two mass points in fixed locations are optimal.

@misc{Tahmasbi2018a,
author = {Tahmasbi, Mehrdad and Savard, Anne and Bloch, Matthieu R},
title = {Covert Capacity of Non-Coherent Rayleigh-Fading Channels},
howpublished = {accepted to \emph{IEEE Transactions on Information Theory}},
month = nov,
year = {2019},
doi = {10.1109/TIT.2019.2956489},
eprint = {1810.07687},
groups = {Steganography and covert communications}
}