[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-83887-en":3,"doc-seo-83887-105":30,"detail-sidebar-cat-0-en-105":91},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":21,"is_downloadable":21,"audit_status":21,"page_count":22,"language":23,"language_code":24,"site_id":25,"html_lang":24,"table_of_contents":26,"faqs":27,"seo_title":13,"seo_description":14,"update_tm":28,"read_time":29},83887,8796095461564,"Liam","https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d",8,"Research & Report","Security Analysis of RIS-Assisted Physical-Layer Authentication Over Multipath Channels","Physical-layer authentication verifies a user’s identity using transmission-channel characteristics observed by the receiver Bob. This work studies a RIS-assisted setup where Bob controls a reconfigurable intelligent surface and Alice sends with a single antenna, while attacker Trudy uses multiple antennas and precoding to fool Bob. With full channel knowledge, the paper derives Trudy’s optimal attack strategy and analyzes when Bob’s estimated channel is indistinguishable under Alice versus Trudy transmission. Multipath prevents indistinguishability, while single-path LOS enables successful impersonation, supported by numerical validation.","Security Analysis of RIS-Assisted Physical-Layer Authentication Over Multipath Channels  \nLinda Senigagliesi 1 , Anna V. Guglielmi2 , Marco Baldi3 , and Stefano Tomasin2  \n1ETIS UMR 8051, CYU, ENSEA, CNRS, Cergy, France, 2University of Padova, Italy,  \n3Universit Politecnica delle Marche, Ancona, Italy  \nemail: [linda.senigagliesi@ensea.fr](linda.senigagliesi@ensea.fr),{annavaleria.guglielmi, [stefano.tomasin](stefano.tomasin}@unipd.it)[}](stefano.tomasin}@unipd.it)[@unipd.it](stefano.tomasin}@unipd.it), [m.baldi@staff.univpm.it](m.baldi@staff.univpm.it)  \narXiv :2607 .05042v 1 [ cs .IT] 6 Jul 2026  \nAbstract—In physical layer authentication, verification of a user’s identity is based on the characteristics of the transmission channel through which signals are delivered to the authenticator (Bob). In this paper, we assume that the signals received by Bob pass through a reconfigurable intelligent surface (RIS) (controlled by Bob) and that the legitimate transmitter (Alice) is equipped with one antenna. Conversely, the attacker (Trudy) has multiple antennas and uses precoding to deceive Bob’s verification. Assuming that Trudy knows all the channel matrices, we first derive her optimal attack strategy. Then, we analyse the conditions under which the channel estimated by Bob is indistinguishable when either Alice or Trudy is transmitting. When Trudy has a single antenna, we show that the indistinguishability condition cannot be met when the channels to the RIS are the result of propagation over multiple paths. For single-path line-of-sight (LOS) conditions, instead, Trudy can impersonate Alice although transmitting from a different position. We verify these results numerically and assess the security of the considered scenario, even when the indistinguishability conditions cannot be met.  \nIndex Terms—Physical Layer Authentication, Reconfigurable Intelligent Surface, Impersonation Attack, Line of Sight.  \nI. INTRODUCTION  \nAuthentication is the process by which a receiver can verify the identity of a transmitter. Authentication mechanisms based on cryptographic algorithms remain secure provided that no computational breakthrough occurs, i.e., for new attack algorithms or the introduction of quantum computing. They typically entail high complexity, unsuitable in scenarios with limited power and computational resources, e.g., the Internet of Things. Alternative approaches are based on informationtheoretic or physical-layer security, which are not affected by the computational capability of attackers. In physical layer authentication (PLA), transmitters are differentiated only based on the electromagnetic characteristics of their transmission channels.  \nPLA has been studied in the literature for quite some time, using various features of received signals, such as channel frequency response (CFR) and channel impulse response (CIR), to distinguish a legitimate user from a potential attacker, [1] .  \nM. Baldi is supported by the project SERICS (PE00000014) under the MUR National Recovery and Resilience Plan, funded by the European Union- Next Generation EU. M. Baldi and S. Tomasin are in part supported by European Union (EU) COST Action CA22168—Physical Layer Security for Trustworthy and Resilient 6G Systems (6G-PHYSEC) . The work of L. Senigagliesi and S. Tomasin are supported by the European Commission through the Horizon Europe/Smart Networks and Services Joint Undertaking (JU SNS) Project ROBUST-6G under Grant 101139068 .  \nRecently, the angle of arrival (AoA) of the signal has been shown to be a robust feature for PLA,[2], [3] . In addition, user classification has been done using both classical statistical approaches and modern tools based on machine learning.  \nIn parallel, wireless communications have evolved through the introduction of RISs that, with their ability to shape the propagation environment, improve energy efficiency, reduce hardware complexity, and improve coverage. RISs have also been considered to improve PLA. Va","cbCaihy3T83xUCu8","https://ap.wps.com/l/cbCaihy3T83xUCu8","pdf",2773156,3,1,6,"English","en",105,"# Introduction\n## Physical-layer authentication overview\n## RIS and authentication motivation\n## Contributions and scenario model\n# Security analysis and attack strategy\n## Optimal impersonation with full channel knowledge\n## Channel indistinguishability conditions\n## AoA-based results for single-antenna attacker\n# Numerical verification and security assessment\n## Simulation results\n## Practical implications","[{\"question\":\"How does the authentication decision work in this RIS-assisted physical-layer authentication model?\",\"answer\":\"Bob verifies identity using channel characteristics estimated from signals reflected through a RIS he controls. Alice transmits normally, while Trudy attempts to make the estimated channel match her impersonation goal.\"},{\"question\":\"What assumption is made about Trudy’s knowledge and capabilities?\",\"answer\":\"Trudy is assumed to know all channel matrices and to have multiple antennas, enabling precoding to deceive Bob’s verification process.\"},{\"question\":\"When can Trudy successfully impersonate Alice, and what happens under multipath?\",\"answer\":\"With a single-path line-of-sight (LOS) condition, Trudy can impersonate Alice from a different position. Under multipath propagation to the RIS, the indistinguishability condition cannot be satisfied, preventing success.\"}]",1784191234,15,{"code":4,"msg":31,"data":32},"ok",{"site_id":25,"language":24,"slug":33,"title":13,"keywords":34,"description":14,"schema_data":35,"social_meta":86,"head_meta":88,"extra_data":90,"updated_unix":28},"security-analysis-of-ris-assisted-physical-layer-authentication-over-multipath-channels","",{"@graph":36,"@context":85},[37,53,68],{"@type":38,"itemListElement":39},"BreadcrumbList",[40,44,48,50],{"item":41,"name":42,"@type":43,"position":21},"https://docshare.wps.com","Home","ListItem",{"item":45,"name":46,"@type":43,"position":47},"https://docshare.wps.com/document/","Document",2,{"item":49,"name":12,"@type":43,"position":20},"https://docshare.wps.com/document/research-report/",{"item":51,"name":13,"@type":43,"position":52},"https://docshare.wps.com/document/security-analysis-of-ris-assisted-physical-layer-authentication-over-multipath-channels/83887/",4,{"url":51,"name":13,"@type":54,"author":55,"headline":13,"publisher":57,"fileFormat":60,"inLanguage":24,"description":14,"dateModified":61,"datePublished":62,"encodingFormat":60,"isAccessibleForFree":63,"interactionStatistic":64},"DigitalDocument",{"name":9,"@type":56},"Person",{"url":41,"name":58,"@type":59},"DocShare","Organization","application/pdf","2026-07-27","2026-07-16",true,{"@type":65,"interactionType":66,"userInteractionCount":20},"InteractionCounter",{"@type":67},"ViewAction",{"@type":69,"mainEntity":70},"FAQPage",[71,77,81],{"name":72,"@type":73,"acceptedAnswer":74},"How does the authentication decision work in this RIS-assisted physical-layer authentication model?","Question",{"text":75,"@type":76},"Bob verifies identity using channel characteristics estimated from signals reflected through a RIS he controls. Alice transmits normally, while Trudy attempts to make the estimated channel match her impersonation goal.","Answer",{"name":78,"@type":73,"acceptedAnswer":79},"What assumption is made about Trudy’s knowledge and capabilities?",{"text":80,"@type":76},"Trudy is assumed to know all channel matrices and to have multiple antennas, enabling precoding to deceive Bob’s verification process.",{"name":82,"@type":73,"acceptedAnswer":83},"When can Trudy successfully impersonate Alice, and what happens under multipath?",{"text":84,"@type":76},"With a single-path line-of-sight (LOS) condition, Trudy can impersonate Alice from a different position. 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