Talk: Dipl.-Ing. Carsten Janda (February 28, 2023 at 10:00 AM, Seminar room N2408, Zoom)
Physical Layer Security - Wiretap Channels with Active Adversary
Dipl.-Ing. Carsten Janda
Institute for Communications Technology
Technical University Braunschweig
Secure communication in a potentially hostile environment is becoming more and more critical. The Arbitrarily Varying Wiretap Channel (AVWC) provides information-theoretical bounds on how much information can be exchanged even in the presence of an active attacker. If the active attacker has non-causal side information, situations in which a legitimate communi- cation system has been hacked can be modeled. We investigate the AVWC with non-causal side information at the jammer for the case that there exists a best channel to the eavesdropper. Non- causal side information means that the transmitted codeword is known to an active adversary before it is transmitted. By considering the maximum error criterion, we also allow messages to be known at the jammer before the corresponding codeword is transmitted. A single-letter formula for the Com- mon Randomness (CR)-assisted secrecy capacity is derived. Additionally, we provide a formula for the CR-assisted secrecy capacity for the cases where the channel to the eavesdropper is strongly de- graded, strongly noisier, or strongly less capable with respect to the main channel. Furthermore, we compare our results to the CR-assisted secrecy capacity for the cases of maximum error criterion but without non-causal side information at the jammer (blind adversary), maximum error criterion with non-causal side information of the messages at the jammer (semi-blind adversary), and the case of average error criterion without non-causal side information at the jammer (blind adversary). In the considered system model, the worst case occurs if the codewords (channel inputs) are non-causally known at the jammer. Secondly, we present a multi-letter expression for an achievable CR-assisted secrecy rate of an AVWC with input and state constraints. We have seen that the proof technique of  is applicable with some changes and adaptations. Chen et al. extended our result in  and derived upper and lower bounds on the secrecy capacity and CR-assisted secrecy capacity. Our tools are pretty strong to prove the achievability. Although we only provide a multi-letter description of an achievable CR-assisted secrecy rate of an AVWC with input and state constraints, we can formulate statements about crucial properties of the AVWC, such as the continuity or super additivity. Thus, we provided a valid result.
 M. Wiese, J. Nötzel, and H. Boche, “A Channel under Simultaneous Jamming and Eavesdropping Attack - Correlated Random Coding Capacities under Strong Secrecy Criteria,” IEEE Trans. Inf. Theory, vol. 62, no. 7, pp. 3844–3862, Jul. 2016. doi: 10. 1109/TIT.2016.2565482.
 Y. Chen, D. He, C. Ying, and Y. Luo, “Strong Secrecy of Arbitrarily Varying Wiretap Channel with Constraints,” IEEE Trans. Inf. Theory, vol. 68, no. 7, pp. 4700–4722, Jul. 2022. doi: 10.1109/TIT.2022.3161808.
Carsten Janda received the academic degree of Dipl.-Ing. in electrical engineering from the Technical University of Dresden in 2011. From 2013 to 2019, he was a research associate at the Chair of Theoretical Communications Engineering at the Faculty of Electrical Engineering and Information Technology at TU Dresden. Since 2019, he is a research associate in the Information Theory and Communication Systems group at the Institute of Communications Engineering at the Technische Universität Braunschweig.