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webSPDZ: Versatile MPC on the Web
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"> <link href="/css/dist/css/bootstrap.min.css" rel="stylesheet"> <title>webSPDZ: Versatile MPC on the Web</title> <link rel="stylesheet" href="/css/eprint.css?v=10"> <style> a.toggle-open:after { content:' -'; font-weight: 800; } a.toggle-closed:after { content: " ›"; font-weight: 800; } .paper-abstract { white-space: pre-wrap; } #metadata dt { margin-top: 1rem; } #metadata dt + dd { /* gap between dt and first dd */ margin-top: .75rem; } #metadata dd { margin-left: 2rem; } #metadata dd.keywords { padding-bottom: .5rem; } span.authorName { margin-top: .5rem; font-style: italic; } </style> <script> MathJax = { tex: { inlineMath: [['$', '$'], ['\\(', '\\)']], displayMath: [ ['$$','$$'], ["\\[","\\]"] ], processEnvironments: false }, loader: { load: [ "ui/safe", "ui/lazy", ], }, options: { safeOptions: { allow: { URLs: "none", classes: "safe", cssIDs: "safe", styles: "safe", }, }, } }; </script> <script id="MathJax-script" async src="/js/mathjax/tex-chtml.js"></script> <meta name="citation_title" content="webSPDZ: Versatile MPC on the Web"> <meta name="citation_author" content="Thomas Buchsteiner"> <meta name="citation_author" content="Karl W. Koch"> <meta name="citation_author" content="Dragos Rotaru"> <meta name="citation_author" content="Christian Rechberger"> <meta name="citation_journal_title" content="Cryptology ePrint Archive"> <meta name="citation_publication_date" content="2025"> <meta name="citation_pdf_url" content="https://eprint.iacr.org/2025/487.pdf"> <meta property="og:image" content="https://eprint.iacr.org/img/iacrlogo.png"/> <meta property="og:image:alt" content="IACR logo"/> <meta property="og:url" content="https://eprint.iacr.org/2025/487"> <meta property="og:site_name" content="IACR Cryptology ePrint Archive" /> <meta property="og:type" content="article" /> <meta property="og:title" content="webSPDZ: Versatile MPC on the Web" /> <meta property="og:description" content="Multi-party computation (MPC) has become increasingly practical in the last two decades, solving privacy and security issues in various domains, such as healthcare, finance, and machine learning. One big caveat is that MPC sometimes lacks usability since the knowledge barrier for regular users can be high. Users have to deal with, e.g., various CLI tools, private networks, and sometimes even must install many dependencies, which are often hardware-dependent. A solution to improve the usability of MPC is to build browser-based MPC engines where each party runs within a browser window. Two examples of such an MPC web engine are JIFF and the web variant of MPyC. Both support an honest majority with passive corruptions. $\texttt{webSPDZ}$: Our work brings one of the most performant and versatile general-purpose MPC engines, MP-SPDZ, to the web. MP-SPDZ supports ≥40 MPC protocols with different security models, enabling many security models on the web. To port MP-SPDZ to the web, we use Emscripten to compile MP-SPDZ’s C++ BackEnd to WebAssembly and upgrade the party communication for the browser (WebRTC or WebSockets). We call the new MPC web engine webSPDZ. As with the native versions of the mentioned MPC web engines, MPyC-Web and JIFF, webSPDZ outperforms them in our end-to-end experiments. We believe that webSPDZ brings forth many interesting and practically relevant use cases. Thus, webSPDZ pushes the boundaries of practical MPC: making MPC more usable and enabling it for a broader community." /> <meta property="article:section" content="IMPLEMENTATION" /> <meta property="article:modified_time" content="2025-03-14T07:30:45+00:00" /> <meta property="article:published_time" content="2025-03-14T07:30:45+00:00" /> <meta property="article:tag" content="Privacy-Enhancing Technology" /> <meta property="article:tag" content="Private Computations" /> <meta property="article:tag" content="Multi-Party Computation" /> <meta property="article:tag" content="MP-SPDZ" /> <meta property="article:tag" content="MPC Web Engine" /> <meta property="article:tag" content="webSPDZ" /> </head> <body> <noscript> <h1 class="text-center">What a lovely hat</h1> <h4 class="text-center">Is it made out of <a href="https://iacr.org/tinfoil.html">tin foil</a>?</h4> </noscript> <div class="fixed-top" id="topNavbar"> <nav class="navbar navbar-custom navbar-expand-lg"> <div class="container px-0 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class="author"><span class="authorName">Thomas Buchsteiner</span><span class="affiliation">, Graz University of Technology</span></div> <div class="author"><span class="authorName">Karl W. Koch</span><a class="ms-1" target="_blank" href="https://orcid.org/0000-0002-4828-7587"><img class="align-baseline orcidIcon" src="/img/orcid.svg"></a><span class="affiliation">, Graz University of Technology</span><span class="affiliation">, Secure Information Technology Center Austria (A-SIT)</span></div> <div class="author"><span class="authorName">Dragos Rotaru</span><a class="ms-1" target="_blank" href="https://orcid.org/0000-0002-1767-3725"><img class="align-baseline orcidIcon" src="/img/orcid.svg"></a><span class="affiliation">, Gateway</span></div> <div class="author"><span class="authorName">Christian Rechberger</span><a class="ms-1" target="_blank" href="https://orcid.org/0000-0003-1280-6020"><img class="align-baseline orcidIcon" src="/img/orcid.svg"></a><span class="affiliation">, Graz University of Technology</span></div> <h5 class="mt-3">Abstract</h5> <p style="white-space: pre-wrap;">Multi-party computation (MPC) has become increasingly practical in the last two decades, solving privacy and security issues in various domains, such as healthcare, finance, and machine learning. One big caveat is that MPC sometimes lacks usability since the knowledge barrier for regular users can be high. Users have to deal with, e.g., various CLI tools, private networks, and sometimes even must install many dependencies, which are often hardware-dependent. A solution to improve the usability of MPC is to build browser-based MPC engines where each party runs within a browser window. Two examples of such an MPC web engine are JIFF and the web variant of MPyC. Both support an honest majority with passive corruptions. $\texttt{webSPDZ}$: Our work brings one of the most performant and versatile general-purpose MPC engines, MP-SPDZ, to the web. MP-SPDZ supports ≥40 MPC protocols with different security models, enabling many security models on the web. To port MP-SPDZ to the web, we use Emscripten to compile MP-SPDZ’s C++ BackEnd to WebAssembly and upgrade the party communication for the browser (WebRTC or WebSockets). We call the new MPC web engine webSPDZ. As with the native versions of the mentioned MPC web engines, MPyC-Web and JIFF, webSPDZ outperforms them in our end-to-end experiments. We believe that webSPDZ brings forth many interesting and practically relevant use cases. Thus, webSPDZ pushes the boundaries of practical MPC: making MPC more usable and enabling it for a broader community.</p> <p><strong>Note:</strong> webSPDZ source code @ GitHub: https://github.com/tbuchs/webSPDZ</p> </div> <div id="metadata" class="col-md-5 col-lg-4 ps-md-5 mt-4 mt-md-0"> <h5>Metadata</h5> <dl> <dt> Available format(s) </dt> <dd> <a class="btn btn-sm btn-outline-dark" href="/2025/487.pdf"> <img class="icon" src="/img/file-pdf.svg">PDF</a> </dd> <dt>Category</dt> <dd><a href="/search?category=IMPLEMENTATION"><small class="badge category category-IMPLEMENTATION">Implementation</small></a></dd> <dt>Publication info</dt> <dd>Preprint. </dd> <dt>Keywords</dt> <dd class="keywords"><a href="/search?q=Privacy-Enhancing%20Technology" class="me-2 badge bg-secondary keyword">Privacy-Enhancing Technology</a><a href="/search?q=Private%20Computations" class="me-2 badge bg-secondary keyword">Private Computations</a><a href="/search?q=Multi-Party%20Computation" class="me-2 badge bg-secondary keyword">Multi-Party Computation</a><a href="/search?q=MP-SPDZ" class="me-2 badge bg-secondary keyword">MP-SPDZ</a><a href="/search?q=MPC%20Web%20Engine" class="me-2 badge bg-secondary keyword">MPC Web Engine</a><a href="/search?q=webSPDZ" class="me-2 badge bg-secondary keyword">webSPDZ</a></dd> <dt>Contact author(s)</dt> <dd><span class="font-monospace"> thomas buchsteiner<span class="obfuscate"> @ </span>gmail com<br>karl koch<span class="obfuscate"> @ </span>tugraz at<br>dragos<span class="obfuscate"> @ </span>mygateway xyz<br>christian rechberger<span class="obfuscate"> @ </span>tugraz at </span> </dd> <dt>History</dt> <dd>2025-03-17: approved</dd> <dd>2025-03-14: received</dd> <dd><a rel="nofollow" href="/archive/versions/2025/487">See all versions</a></dd> <dt>Short URL</dt> <dd><a href="https://ia.cr/2025/487">https://ia.cr/2025/487</a></dd> <dt>License</dt> <dd><a rel="license" target="_blank" href="https://creativecommons.org/licenses/by/4.0/"> <img class="licenseImg" src="/img/license/CC_BY.svg" alt="Creative Commons Attribution" title="Creative Commons Attribution"><br> <small>CC BY</small> </a> </dd> </dl> </div> </div> <p class="mt-4"><strong>BibTeX</strong> <button id="bibcopy" class="ms-2 btn btn-sm btn-outline-dark" aria-label="Copy to clipboard" onclick="copyBibtex()"> <img src="/img/copy-outline.svg" class="icon">Copy to clipboard</button></p> <pre id="bibtex"> @misc{cryptoeprint:2025/487, author = {Thomas Buchsteiner and Karl W. Koch and Dragos Rotaru and Christian Rechberger}, title = {{webSPDZ}: Versatile {MPC} on the Web}, howpublished = {Cryptology {ePrint} Archive, Paper 2025/487}, year = {2025}, url = {https://eprint.iacr.org/2025/487} } </pre> <script> var bibcopy; function triggerTooltip() { console.log('setting tooltip'); } window.onload = triggerTooltip; function copyBibtex() { let range = document.createRange(); range.selectNode(document.getElementById('bibtex')); window.getSelection().removeAllRanges(); window.getSelection().addRange(range); document.execCommand('copy'); window.getSelection().removeAllRanges(); let bibcopy = document.getElementById('bibcopy'); let copyTooltip = new bootstrap.Tooltip(bibcopy, {trigger: 'manual', title: 'Copied!'}); copyTooltip.show(); setTimeout(function() { copyTooltip.dispose(); }, 2000); } </script> </main> <div class="container-fluid mt-auto" id="eprintFooter"> <a href="https://iacr.org/"> <img id="iacrlogo" src="/img/iacrlogo_small.png" class="img-fluid d-block mx-auto" alt="IACR Logo"> </a> <div class="colorDiv"></div> <div class="alert alert-success w-75 mx-auto"> Note: In order to protect the privacy of readers, eprint.iacr.org does not use cookies or embedded third party content. </div> </div> <script src="/css/bootstrap/js/bootstrap.bundle.min.js"></script> <script> var topNavbar = document.getElementById('topNavbar'); if (topNavbar) { document.addEventListener('scroll', function(e) { if (window.scrollY > 100) { topNavbar.classList.add('scrolled'); } else { topNavbar.classList.remove('scrolled'); } }) } </script> </body> </html>