{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:49:17Z","timestamp":1760240957629,"version":"build-2065373602"},"reference-count":47,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2019,10,28]],"date-time":"2019-10-28T00:00:00Z","timestamp":1572220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key R&amp;D Program of China","award":["2018YFB0803901","2017YFB0802700"],"award-info":[{"award-number":["2018YFB0803901","2017YFB0802700"]}]},{"name":"the Fundamental Research Funds for the Central Universities","award":["JB191503"],"award-info":[{"award-number":["JB191503"]}]},{"DOI":"10.13039\/501100001809","name":"the National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 61772404, U1836203"],"award-info":[{"award-number":["No. 61772404, U1836203"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"China 111 Project","award":["-"],"award-info":[{"award-number":["-"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Secure information exchange occurs in many recently emerging cooperative-based networks, such as 5G networks (especially those with a Device to Device architecture), the Internet of Things, and vehicular ad hoc networks. However, the existing information exchange protocols only focus on either pairwise information exchange or group information exchange, and none of these protocols enable private and public information exchange to occur simultaneously. Thus, a general secure information exchange protocol for a multiuser channel is desirable. With this motivation, this paper investigates simultaneous private and public information exchange in a Multiple Inputs Multiple Outputs (MIMO) multiuser relay channel. In an aim to achieve this goal, signal alignment is chosen as the core technique. With the designed precoding matrix for each user, private information is aligned with its exchange partner, and public information forms a coding chain at the relay. With the aligned private signal and public coding chain, neither an untrusted relay nor external eavesdroppers can recover the original individual information. Performance analyses of the proposed protocol are conducted. First, we conduct transmission performance analyses from the perspective of time slot cost. Second, we conduct a security analysis for private information exchange and public information exchange. Third, we conduct secrecy sum-rate analysis for three attack scenarios: an untrusted relay attack only, an eavesdropper attack only, and both an untrusted relay and eavesdropper attack. The simulations are conducted to demonstrate that the proposed protocol can enable simultaneous private and public information exchange while resisting attacks by an undesired receiver, an untrusted relay, and external eavesdroppers.<\/jats:p>","DOI":"10.3390\/e21111054","type":"journal-article","created":{"date-parts":[[2019,10,28]],"date-time":"2019-10-28T11:26:13Z","timestamp":1572261973000},"page":"1054","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["General Secure Information Exchange Protocol for a Multiuser MIMO Relay Channel"],"prefix":"10.3390","volume":"21","author":[{"given":"Qiao","family":"Liu","sequence":"first","affiliation":[{"name":"School of Cyber Engineering, Xidian University, Xi\u2019an 710126, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hui","family":"Li","sequence":"additional","affiliation":[{"name":"School of Cyber Engineering, Xidian University, Xi\u2019an 710126, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yong","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Cyber Engineering, Xidian University, Xi\u2019an 710126, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,10,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3715","DOI":"10.1109\/TWC.2015.2410293","article-title":"Interference Alignment in Device-to-Device LAN Underlaying Cellular Networks","volume":"14","author":"Yang","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"71099","DOI":"10.1109\/ACCESS.2018.2881338","article-title":"Joint Space-Frequency Block Codes and Signal Alignment for Heterogeneous Networks","volume":"6","author":"Ali","year":"2018","journal-title":"IEEE Access"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"5648","DOI":"10.1109\/TWC.2014.2322855","article-title":"Set Optimization for Efficient Interference Alignment in Heterogeneous Networks","volume":"13","author":"Castanheira","year":"2014","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Khan, R., Kumar, P., Jayakody, D.N.K., and Liyanage, M. (2019). A Survey on Security and Privacy of 5G Technologies: Potential Solutions, Recent Advancements and Future Directions. IEEE Commun. Surv. Tutor.","DOI":"10.1109\/COMST.2019.2933899"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.jnca.2016.11.002","article-title":"A survey on device-to-device (D2D) communication: Architecture and security issues","volume":"78","author":"Gandotra","year":"2017","journal-title":"J. Netw. Comput. Appl."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Oohama, Y. (2007, January 24\u201329). Capacity theorems for relay channels with confidential messages. Proceedings of the 2007 IEEE International Symposium on Information Theory (ISIT 2007), Nice, France.","DOI":"10.1109\/ISIT.2007.4557113"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1550","DOI":"10.1109\/SURV.2014.012314.00178","article-title":"Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey","volume":"16","author":"Mukherjee","year":"2014","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"4005","DOI":"10.1109\/TIT.2008.928272","article-title":"The Relay-Eavesdropper Channel: Cooperation for Secrecy","volume":"54","author":"Lai","year":"2008","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1109\/LSP.2012.2227313","article-title":"Cooperative Secure Beamforming for AF Relay Networks With Multiple Eavesdroppers","volume":"20","author":"Yang","year":"2013","journal-title":"IEEE Signal Process. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"3461","DOI":"10.1109\/TCOMM.2012.081012.110236","article-title":"A General Relaying Transmission Protocol for MIMO Secrecy Communications","volume":"60","author":"Ding","year":"2012","journal-title":"IEEE Trans. Commun."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1676","DOI":"10.1109\/LCOMM.2013.062113.131012","article-title":"An Effective Secure Transmission Scheme for AF Relay Networks with Two-Hop Information Leakage","volume":"17","author":"Lin","year":"2013","journal-title":"IEEE Commun. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1109\/TWC.2014.2354635","article-title":"Hybrid Opportunistic Relaying and Jamming With Power Allocation for Secure Cooperative Networks","volume":"14","author":"Wang","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1117","DOI":"10.1109\/TPDS.2014.2316155","article-title":"Secrecy Capacity Optimization via Cooperative Relaying and Jamming for WANETs","volume":"26","author":"Han","year":"2015","journal-title":"IEEE Trans. Parallel Distrib. Syst."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"310","DOI":"10.1109\/TIFS.2011.2166386","article-title":"Joint Relay and Jammer Selection for Secure Two-Way Relay Networks","volume":"7","author":"Chen","year":"2012","journal-title":"IEEE Trans. Inf. Forensics Secur."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2099","DOI":"10.1109\/JSAC.2013.131011","article-title":"Optimal Relay Selection for Physical-Layer Security in Cooperative Wireless Networks","volume":"31","author":"Zou","year":"2013","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"624","DOI":"10.1109\/TIFS.2013.2297835","article-title":"When Does Relay Transmission Give a More Secure Connection in Wireless Ad Hoc Networks?","volume":"9","author":"Cai","year":"2014","journal-title":"IEEE Trans. Inf. Forensics Secur."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1109\/TIT.2012.2216952","article-title":"Strong Secrecy and Reliable Byzantine Detection in the Presence of an Untrusted Relay","volume":"59","author":"He","year":"2013","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1109\/LCOMM.2014.2385095","article-title":"Security-Aware Relaying Scheme for Cooperative Networks With Untrusted Relay Nodes","volume":"19","author":"Sun","year":"2015","journal-title":"IEEE Commun. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1109\/WCL.2014.031114.140018","article-title":"Secure Transmission with Optimal Power Allocation in Untrusted Relay Networks","volume":"3","author":"Wang","year":"2014","journal-title":"IEEE Wirel. Commun. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"310","DOI":"10.1109\/TSP.2011.2172433","article-title":"Joint Secure Beamforming Design at the Source and the Relay for an Amplify-and-Forward MIMO Untrusted Relay System","volume":"60","author":"Jeong","year":"2012","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3170","DOI":"10.1109\/TWC.2012.070912.111293","article-title":"Physical Layer Integration of Private, Common, and Confidential Messages in Bidirectional Relay Networks","volume":"11","author":"Wyrembelski","year":"2012","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"8115","DOI":"10.1109\/TIT.2013.2281711","article-title":"The Role of Feedback in Two-Way Secure Communications","volume":"59","author":"He","year":"2013","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3532","DOI":"10.1109\/TSP.2012.2191543","article-title":"Distributed Beamforming for Physical-Layer Security of Two-Way Relay Networks","volume":"60","author":"Wang","year":"2012","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2111","DOI":"10.1109\/TSP.2014.2303942","article-title":"Algorithms for Secrecy Guarantee With Null Space Beamforming in Two-Way Relay Networks","volume":"62","author":"Yang","year":"2014","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1270","DOI":"10.1109\/LCOMM.2014.2325861","article-title":"Secure Beamforming Design for Physical Layer Network Coding Based MIMO Two-Way Relaying","volume":"18","author":"Jayasinghe","year":"2014","journal-title":"IEEE Commun. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3280","DOI":"10.1109\/TWC.2015.2403367","article-title":"Joint Beamforming and Power Allocation for Secrecy in Peer-to-Peer Relay Networks","volume":"14","author":"Wang","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"3856","DOI":"10.1109\/TWC.2016.2530068","article-title":"Exploiting Direct Links for Physical Layer Security in Multiuser Multirelay Networks","volume":"15","author":"Fan","year":"2016","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"5904","DOI":"10.1109\/TWC.2016.2572681","article-title":"Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF\/FSO Relay Networks With Opportunistic User Scheduling","volume":"15","author":"Salhab","year":"2016","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"8009","DOI":"10.1109\/TWC.2016.2610965","article-title":"Secure Multiuser Scheduling in Downlink Dual-Hop Regenerative Relay Networks Over Nakagami-m Fading Channels","volume":"15","author":"Yang","year":"2016","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2185","DOI":"10.1109\/TSP.2014.2307276","article-title":"Secure Beamforming for MIMO Two-Way Communications With an Untrusted Relay","volume":"62","author":"Mo","year":"2014","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/TWC.2012.120412.101358","article-title":"End-to-End Secure Multi-Hop Communication with Untrusted Relays","volume":"12","author":"He","year":"2013","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2531","DOI":"10.1109\/TIT.2015.2412114","article-title":"Secure Compute-and-Forward in a Bidirectional Relay","volume":"61","author":"Vatedka","year":"2015","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4520","DOI":"10.1109\/TWC.2014.2318050","article-title":"Achievable Degrees of Freedom for K-User MIMO Y Channels Using Signal Group Based Alignment","volume":"13","author":"Mu","year":"2014","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"849","DOI":"10.1109\/LCOMM.2017.2648795","article-title":"On the Performance of Zero-Forcing Processing in Multi-Way Massive MIMO Relay Networks","volume":"21","author":"Ho","year":"2017","journal-title":"IEEE Commun. Lett."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1109\/JSAC.2014.2384352","article-title":"Degrees of Freedom of MIMO Multiway Relay Channel With Clustered Pairwise Exchange","volume":"33","author":"Wang","year":"2015","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5747","DOI":"10.1109\/ACCESS.2017.2694478","article-title":"Physical Layer Security Based on Interference Alignment in K-User MIMO Y Wiretap Channels","volume":"5","author":"Fan","year":"2017","journal-title":"IEEE Access"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"903","DOI":"10.1007\/s00779-017-1049-6","article-title":"Secure group information exchange scheme for vehicular ad hoc networks","volume":"21","author":"Zhou","year":"2017","journal-title":"Pers. Ubiquitous Comput."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"41139","DOI":"10.1109\/ACCESS.2018.2857214","article-title":"MIMO Multiway Distributed Relay Channel With Full Data Exchange: An Achievable Rate Perspective","volume":"6","author":"Yuan","year":"2018","journal-title":"IEEE Access"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Franz, M., Deiseroth, B., Hamacher, K., Jha, S., Katzenbeisser, S., and Schr\u00f6der, H. (2010, January 12\u201315). Secure computations on non-integer values. Proceedings of the 2010 IEEE International Workshop on Information Forensics and Security (WIFS 2010), Seattle, WA, USA.","DOI":"10.1109\/WIFS.2010.5711458"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1109\/TC.2015.2419662","article-title":"Contributory Broadcast Encryption with Efficient Encryption and Short Ciphertexts","volume":"65","author":"Wu","year":"2015","journal-title":"IEEE Trans. Comput."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2352","DOI":"10.1109\/TIFS.2015.2447933","article-title":"Round-Efficient and Sender-Unrestricted Dynamic Group Key Agreement Protocol for Secure Group Communications","volume":"10","author":"Zhang","year":"2015","journal-title":"IEEE Trans. Inf. Forensics Secur."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2193","DOI":"10.1109\/TVT.2017.2765660","article-title":"Training Based Two-Step Channel Estimation in Two-Way MIMO Relay Systems","volume":"67","author":"Chen","year":"2018","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"737","DOI":"10.1049\/iet-com.2014.0553","article-title":"Semi-blind parallel factor based receiver for joint symbol and channel estimation in amplify-and-forward multiple-input multiple-output relay systems","volume":"9","author":"Du","year":"2015","journal-title":"IET Commun."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Ye, S., Du, J., Deng, R., and Chang, R. (2017, January 7\u20139). A PARAFAC-based Channel Estimation Algorithm for Multi-user MIMO Two-way Relay Systems. Proceedings of the 2017 2nd International Conference on Communication and Information Systems, Wuhan, China.","DOI":"10.1145\/3158233.3159333"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1109\/TWC.2014.2347321","article-title":"Channel Estimation for Two-Way MIMO Relay Systems in Frequency-Selective Fading Environments","volume":"14","author":"Chiong","year":"2015","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Cover, T.M., and Thomas, J.A. (2006). Elements of Information Theory, Wiley. [2nd ed.].","DOI":"10.1002\/047174882X"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"973","DOI":"10.1109\/TCOMM.2012.010213.120265","article-title":"A New Physical-Layer Network Coding Scheme with Eigen-Direction Alignment Precoding for MIMO Two-Way Relaying","volume":"61","author":"Yang","year":"2013","journal-title":"IEEE Trans. Commun."}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/21\/11\/1054\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:29:59Z","timestamp":1760189399000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/21\/11\/1054"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,10,28]]},"references-count":47,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2019,11]]}},"alternative-id":["e21111054"],"URL":"https:\/\/doi.org\/10.3390\/e21111054","relation":{},"ISSN":["1099-4300"],"issn-type":[{"type":"electronic","value":"1099-4300"}],"subject":[],"published":{"date-parts":[[2019,10,28]]}}}