eprintid: 10199016 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/19/90/16 datestamp: 2024-10-29 10:02:44 lastmod: 2024-10-29 10:02:44 status_changed: 2024-10-29 10:02:44 type: article metadata_visibility: show sword_depositor: 699 creators_name: Xu, Hao creators_name: Wong, Kai-Kit creators_name: Caire, Giuseppe title: A New Achievable Region of the K-User MAC Wiretap Channel with Confidential and Open Messages Under Strong Secrecy ispublished: inpress divisions: UCL divisions: B04 divisions: F46 keywords: Discrete memoryless (DM) multiple access wiretap (MAC-WT) channel; strong secrecy; secret and open messages; achievable rate region note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: This paper investigates the achievable region of a K -user discrete memoryless (DM) multiple access wiretap (MAC-WT) channel, where each user transmits both secret and open (i.e., non-confidential) messages. All these messages are intended for the legitimate receiver (Bob), while the eavesdropper (Eve) is only interested in the secret messages. In the achievable coding strategy, the confidential information is protected by open messages and also by the introduction of auxiliary messages. When introducing an auxiliary message, one has to ensure that, on one hand, its rate is large enough for protecting the secret message from Eve and, on the other hand, the resulting sum rate (together with the secret and open message rate) does not exceed Bob’s decoding capability. This yields an inequality structure involving the rates of all users’ secret, open, and auxiliary messages. To obtain the rate region, the auxiliary message rates must be eliminated from the system of inequalities. A direct application of the Fourier-Motzkin elimination procedure is elusive since a) it requires that the number of users K is explicitly given, and b) even for small K = 3, 4, …, the number of inequalities becomes extremely large. We prove the result for general K through the combined use of Fourier-Motzkin elimination procedure and mathematical induction. This paper adopts the strong secrecy metric, characterized by information leakage . To prove the achievability under this criterion, we analyze the resolvability region of a K -user DM-MAC channel (not necessarily a wiretap channel). In addition, we show that users with zero secrecy rate can play different roles and use different strategies in encoding their messages. These strategies yield non-redundant (i.e., not mutually dominating) rate inequalities. By considering all possible coding strategies, we provide a new achievable region for the considered channel, and show that it strictly improves those already known in the existing literature by considering a specific example. date: 2024-10-01 date_type: published publisher: Institute of Electrical and Electronics Engineers (IEEE) official_url: http://dx.doi.org/10.1109/tit.2024.3471662 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2327850 doi: 10.1109/TIT.2024.3471662 lyricists_name: Xu, Hao lyricists_name: Wong, Kai-Kit lyricists_id: HXUCX90 lyricists_id: KWONG98 actors_name: Wong, Kai-Kit actors_id: KWONG98 actors_role: owner full_text_status: public publication: IEEE Transactions on Information Theory issn: 0018-9448 citation: Xu, Hao; Wong, Kai-Kit; Caire, Giuseppe; (2024) A New Achievable Region of the K-User MAC Wiretap Channel with Confidential and Open Messages Under Strong Secrecy. IEEE Transactions on Information Theory 10.1109/TIT.2024.3471662 <https://doi.org/10.1109/TIT.2024.3471662>. (In press). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10199016/1/MAC_wiretap.pdf