[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-82741-en":3,"doc-seo-82741-105":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},82741,4398048949847,"Eliana","https://ap-avatar.wpscdn.com/avatar/400002536579ef2da7f?_k=1778318612642679267",8,"Research & Report","LeanDY: Type-Based and Trace-Based Symbolic Protocol Verification in Lean","Computer-aided formal verification is widely used for symbolic analysis of cryptographic protocols, yet many modern protocols challenge existing techniques. Reasoning about global state, time-dependent behavior, inductive data, unbounded executions, and conditional secrecy demands expressiveness that is hard to automate effectively. The work introduces an orthogonal method combining compositional type-based reasoning with trace-based reasoning to modularly verify stateful and unbounded protocols. Implemented as LeanDY for the Lean prover, it supports secrecy and authentication and formalizes SegWit-style blockchain primitives and payment channels.","LeanDY: Type-Based and Trace-Based Symbolic Protocol  \nVerification in Lean  \nSimon Jeanteur  \nTU Wien Vienna, Austria [simon.jeanteur@tuwien.ac.at](simon.jeanteur@tuwien.ac.at)  \nLorenzo Veronese  \nTU Wien Vienna, Austria [lorenzo.veronese@tuwien.ac.at](lorenzo.veronese@tuwien.ac.at)  \nMagdalena Solitro  \nFondazione Bruno Kessler Trento, Italy [msolitro@fbk.eu](msolitro@fbk.eu)  \nMatteo Maffei  \nTU Wien  \nVienna, Austria  \nChristian Doppler Laboratory Blockchain Technologies for the Internet of Things  \nVienna, Austria [matteo.maffei@tuwien.ac.at](matteo.maffei@tuwien.ac.at)  \narXiv :2607 .03406v2 [ cs .CR] 7 Jul 2026  \nAbstract  \nComputer-aided formal verification is a widely used approach for the symbolic analysis of cryptographic protocols. However, many modern protocols rely on features that remain challenging for existing techniques. In particular, reasoning about state, time-dependent behavior, inductively defined data structures, unbounded executions, and conditional secrecy requires a level of expressiveness that is difficult to reconcile with effective automation. As a result, protocol verification has largely followed two disjoint paths: fully automated methods with limited expressiveness, or interactive proofs in general-purpose theorem provers that offer flexibility but only limited, non-specialized automation.  \nWe present an orthogonal approach that bridges this gap by combining compositional type-based reasoning with trace-based reasoning, enabling modular verification of stateful and unbounded protocols. Guided by the language-and-automation co-design (LAC) principle, our approach delivers protocol-specific automation while retaining high expressiveness. We implement this framework asthe LeanDY library for the Lean proof assistant, building on and extending the design of DY*, and combining protocol-specific automation with interactive proofs. Our framework supports, in a unified setting, a broad class of functional and security requirements, including secrecy and authentication for stateful protocols, as well as recursive conditional secrecy for protocols using XOR. We formalize SegWit-style blockchain primitives in LeanDY and demonstrate its expressiveness by carrying out an in-depth formalization of payment channels on top of this blockchain model, verifying punishment mechanisms and properties that depend on chain liveness.  \nThis is the technical report.  \n1 Introduction  \nOver the past decades, computer-aided formal analysis of cryptographic protocols has matured into a widely used set of techniques and has become a key component of real-world protocol analysis. For example, ProVerif [13] and Tamarin [43] have supported the verification of the design of TLS 1.3 [12] and WireGuard [34, 38]; and F∗ [51, 52] has been used to verify the Signal protocol, the core  \nof modern messaging applications [10] . However, many modern protocols rely on features that remain challenging for existing techniques. In particular, reasoning about global state, time-dependent behavior, unbounded executions, and conditional secrecy, i.e., secrets that must remain private only until a specific condition is met, requires a level of expressiveness that is difficult to reconcile with automation. These challenges are particularly prominent for blockchain-based protocols, which, despite their recent adoption in applications such as payment-channel networks, have seen fewer machine-aided verification efforts. The design of such protocols typically relies on a global, high-integrity ledger, requires reasoning across application-level and consensus-level specifications, and often combines safety and liveness arguments. Additionally, they may use constructions such as XOR, whose algebraic properties make symbolic reasoning notoriously difficult [35] . As a result, protocols such as the Lightning Network remain only partially verified, with the notable exceptions being [28], which analyzed the protocol up to a fixed bound, and [26], which ","cbCaifyNB7pstRAa","https://ap.wps.com/l/cbCaifyNB7pstRAa","pdf",753594,2,1,18,"English","en",105,"# Abstract\n# Introduction\n## Challenges in modern protocol verification\n## Two symbolic verification paradigms: trace-based and type-based","[{\"question\":\"What problem does the document address in cryptographic protocol verification?\",\"answer\":\"It addresses the difficulty of verifying modern cryptographic protocols whose features include global state, time-dependent behavior, inductive data structures, unbounded executions, and conditional secrecy. Existing tools struggle to provide sufficient expressiveness while keeping effective automation.\"},{\"question\":\"How does LeanDY combine type-based and trace-based reasoning?\",\"answer\":\"LeanDY bridges automation gaps by combining compositional type-based reasoning with trace-based reasoning. This enables modular verification of stateful and unbounded protocols while guided by language-and-automation co-design.\"},{\"question\":\"What applications and formalizations does LeanDY demonstrate?\",\"answer\":\"The framework formalizes SegWit-style blockchain primitives in LeanDY. It further performs an in-depth formalization of payment channels on top of this blockchain model, including verification of punishment mechanisms and properties depending on chain liveness.\"}]",1784182613,45,{"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},"leandy-type-based-and-trace-based-symbolic-protocol-verification-in-lean","",{"@graph":36,"@context":85},[37,53,68],{"@type":38,"itemListElement":39},"BreadcrumbList",[40,44,47,50],{"item":41,"name":42,"@type":43,"position":21},"https://docshare.wps.com","Home","ListItem",{"item":45,"name":46,"@type":43,"position":20},"https://docshare.wps.com/document/","Document",{"item":48,"name":12,"@type":43,"position":49},"https://docshare.wps.com/document/research-report/",3,{"item":51,"name":13,"@type":43,"position":52},"https://docshare.wps.com/document/leandy-type-based-and-trace-based-symbolic-protocol-verification-in-lean/82741/",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","2026-07-23","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},"What problem does the document address in cryptographic protocol verification?","Question",{"text":75,"@type":76},"It addresses the difficulty of verifying modern cryptographic protocols whose features include global state, time-dependent behavior, inductive data structures, unbounded executions, and conditional secrecy. Existing tools struggle to provide sufficient expressiveness while keeping effective automation.","Answer",{"name":78,"@type":73,"acceptedAnswer":79},"How does LeanDY combine type-based and trace-based reasoning?",{"text":80,"@type":76},"LeanDY bridges automation gaps by combining compositional type-based reasoning with trace-based reasoning. This enables modular verification of stateful and unbounded protocols while guided by language-and-automation co-design.",{"name":82,"@type":73,"acceptedAnswer":83},"What applications and formalizations does LeanDY demonstrate?",{"text":84,"@type":76},"The framework formalizes SegWit-style blockchain primitives in LeanDY. 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