This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ====== Analysis of Input-Output Mappings in Coinjoin Transactions with Arbitrary Values ====== ~~NOTOC~~ <grid> <col xs="12" sm="8" lg="8"> <TEXT size="large"> \_{{fa>user}}\_\_//Authors:// [[:publications:authors:jiri-gavenda|Jiri Gavenda]], [[:publications:authors:petr-svenda|Petr Svenda]], Stanislav BoboĊ, [[:publications:authors:vladimir-sedlacek|Vladimir Sedlacek]] {{fa>user-circle-o}}\_//Primary contact:// Jiri Gavenda %%<%%<gavenda@mail.muni.cz>%%>%% {{fa>bullhorn}}\_//Conference:// [[https://esorics2025.sciencesconf.org/|ESORICS 2025]] </TEXT> </col> <col xs="12" sm="4" lg="4"> <TEXT align="right"> <button type="warning" icon="fa fa-fw fa-file-pdf-o">[[https://crocs.fi.muni.cz/_media/publications/pdf/2025-esorics-gavenda.pdf|PRE-PRINT PDF]]</button> \_ <button icon="fa fa-fw fa-file-image-o">[[https://crocs.fi.muni.cz/_media/publications/pdf/2025-esorics-gavenda_presentation.pdf|SLIDES]]</button> \_ <button collapse="bibtex" icon="fa fa-fw fa-file-code-o">BiBTeX</button> </TEXT> </col> </grid> <collapse id="bibtex" collapsed="false"> @InProceedings{2025-esorics-gavenda, Title = {Analysis of Input-Output Mappings in Coinjoin Transactions with Arbitrary Values}, Author = {Jiri Gavenda and Petr Svenda and Stanislav Bobon and Vladimir Sedlacek}, BookTitle = {Computer Security -- ESORICS 2025}, Pages = {126--146}, Publisher = {Springer Nature Switzerland}, Address = {Cham}, Year = {2025}, ISBN = {978-3-032-07901-5}, DOI = {10.1007/978-3-032-07901-5_7}, Editor = {Vincent Nicomette and Abdelmalek Benzekri and Nora Boulahia-Cuppens and Jaideep Vaidya}, } </collapse> <panel type="default" title="Abstract"> A coinjoin protocol aims to increase transactional privacy for Bitcoin and Bitcoin-like blockchains via collaborative transactions, by violating assumptions behind common analysis heuristics. Estimating the resulting privacy gain is a crucial yet unsolved problem due to a range of influencing factors and large computational complexity. We adapt the BlockSci on-chain analysis software to coinjoin transactions, demonstrating a significant (10-50%) average post-mix anonymity set size decrease for all three major designs with a central coordinator: Whirlpool, Wasabi 1.x, and Wasabi 2.x. The decrease is highest during the first day and negligible after one year from a coinjoin creation. Moreover, we design a precise, parallelizable privacy estimation method, which takes into account coinjoin fees, implementation-specific limitations and users' post-mix behavior. We evaluate our method in detail on a set of emulated and real-world Wasabi 2.x coinjoins and extrapolate to its largest real-world coinjoins with hundreds of inputs and outputs. We conclude that despite the users' undesirable post-mix behavior, correctly attributing the coins to their owners is still very difficult, even with our improved analysis algorithm. </panel> ===== Research artifacts (supplementary material) ===== * [[https://github.com/crocs-muni/coinjoin-mappings | GitHub repository]]