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Towards Permissionless Consensus in the Standard Model via Fine-Grained Complexity
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A number of protocols have been proposed to achieve permissionless consensus, most notably based on the Bitcoin protocol; however, to date no protocol is known that can be provably instantiated outside of the random oracle model. In this work, we take the first steps towards achieving permissionless consensus in the standard model. In particular, we demonstrate that worst-case conjectures in fine-grained complexity, in particular the orthogonal vectors conjecture (implied by the Strong Exponential Time Hypothesis), imply permissionless consensus in the random beacon model—a setting where a fresh random value is delivered to all parties at regular intervals. This gives a remarkable win-win result: either permissionless consensus exists relative to a random beacon, or there are non-trivial worst-case algorithmic speed-ups for a host of natural algorithmic problems (including SAT). Our protocol achieves resilience against adversaries that control an inverse-polynomial fraction of the honest computational power, i.e., adversarial power $A = T^{1−ε} $ for some constant $ε > 0$, where $T$ denotes the honest computational power. This relatively low threshold is a byproduct of the slack in the fine-grained complexity conjectures. One technical highlight is the construction of a Seeded Proof of Work: a Proof of Work where many (correlated) challenges can be derived from a single short public seed, and yet still no non-trivial amortization is possible." /> <meta property="article:section" content="PROTOCOLS" /> <meta property="article:modified_time" content="2024-04-25T22:03:09+00:00" /> <meta property="article:published_time" content="2024-04-25T22:03:09+00:00" /> <meta property="article:tag" content="Consensus" /> <meta property="article:tag" content="proof of work" /> <meta property="article:tag" content="fine-grained complexity" /> </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 justify-content-between justify-content-lg-evenly"> <div class="order-0 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</div> <div class="dropdown ps-md-2 text-right order-2 order-lg-last"> <button class="btn btnNoOutline" type="button" id="dropdownMenuButton1" data-bs-toggle="dropdown" aria-expanded="false"> <img src="/img/search.svg" class="searchIcon" alt="Search Button"/> </button> <div id="searchDd" class="dropdown-menu dropdown-menu-end p-0" aria-labelledby="dropdownMenuButton1"> <form action="/search" method="GET"> <div class="input-group"> <input id="searchbox" name="q" type="search" class="form-control" autocomplete="off"> <button class="btn btn-secondary border input-group-append ml-2"> Search </button> </div> </form> <div class="ms-2 p-1 d-none"><a href="/search">Advanced search</a></div> </div> </div> </div> </nav> </div> <main id="eprintContent" class="container px-3 py-4 p-md-4"> <div class="row mt-4"> <div class="col-md-7 col-lg-8 pe-md-5"> <h4>Paper 2024/637</h4> <h3 class="mb-3">Towards Permissionless Consensus in the Standard Model via Fine-Grained Complexity</h3> <div class="author"><span class="authorName">Marshall Ball</span><span class="affiliation">, NYU</span></div> <div class="author"><span class="authorName">Juan Garay</span><a class="ms-1" target="_blank" href="https://orcid.org/0000-0003-0366-7110"><img class="align-baseline orcidIcon" src="/img/orcid.svg"></a><span class="affiliation">, Texas A&M University</span></div> <div class="author"><span class="authorName">Peter Hall</span><span class="affiliation">, NYU</span></div> <div class="author"><span class="authorName">Aggelos Kiayias</span><span class="affiliation">, University of Edinburgh</span><span class="affiliation">, IOHK</span></div> <div class="author"><span class="authorName">Giorgos Panagiotakos</span><span class="affiliation">, IOHK</span></div> <h5 class="mt-3">Abstract</h5> <p style="white-space: pre-wrap;">We investigate the feasibility of permissionless consensus (aka Byzantine agreement) under standard assumptions. A number of protocols have been proposed to achieve permissionless consensus, most notably based on the Bitcoin protocol; however, to date no protocol is known that can be provably instantiated outside of the random oracle model. In this work, we take the first steps towards achieving permissionless consensus in the standard model. In particular, we demonstrate that worst-case conjectures in fine-grained complexity, in particular the orthogonal vectors conjecture (implied by the Strong Exponential Time Hypothesis), imply permissionless consensus in the random beacon model—a setting where a fresh random value is delivered to all parties at regular intervals. This gives a remarkable win-win result: either permissionless consensus exists relative to a random beacon, or there are non-trivial worst-case algorithmic speed-ups for a host of natural algorithmic problems (including SAT). Our protocol achieves resilience against adversaries that control an inverse-polynomial fraction of the honest computational power, i.e., adversarial power $A = T^{1−ε} $ for some constant $ε > 0$, where $T$ denotes the honest computational power. This relatively low threshold is a byproduct of the slack in the fine-grained complexity conjectures. One technical highlight is the construction of a Seeded Proof of Work: a Proof of Work where many (correlated) challenges can be derived from a single short public seed, and yet still no non-trivial amortization is possible.</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="/2024/637.pdf"> <img class="icon" src="/img/file-pdf.svg">PDF</a> </dd> <dt>Category</dt> <dd><a href="/search?category=PROTOCOLS"><small class="badge category category-PROTOCOLS">Cryptographic protocols</small></a></dd> <dt>Publication info</dt> <dd>Preprint. </dd> <dt>Keywords</dt> <dd class="keywords"><a href="/search?q=Consensus" class="me-2 badge bg-secondary keyword">Consensus</a><a href="/search?q=proof%20of%20work" class="me-2 badge bg-secondary keyword">proof of work</a><a href="/search?q=fine-grained%20complexity" class="me-2 badge bg-secondary keyword">fine-grained complexity</a></dd> <dt>Contact author(s)</dt> <dd><span class="font-monospace"> marshall ball<span class="obfuscate"> @ </span>cs nyu edu<br>garay<span class="obfuscate"> @ </span>cse tamu edu<br>pf2184<span class="obfuscate"> @ </span>nyu edu<br>aggelos kiayias<span class="obfuscate"> @ </span>ed ac uk<br>pagio91i<span class="obfuscate"> @ </span>gmail com </span> </dd> <dt>History</dt> <dd>2024-04-26: approved</dd> <dd>2024-04-25: received</dd> <dd><a rel="nofollow" href="/archive/versions/2024/637">See all versions</a></dd> <dt>Short URL</dt> <dd><a href="https://ia.cr/2024/637">https://ia.cr/2024/637</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:2024/637, author = {Marshall Ball and Juan Garay and Peter Hall and Aggelos Kiayias and Giorgos Panagiotakos}, title = {Towards Permissionless Consensus in the Standard Model via Fine-Grained Complexity}, howpublished = {Cryptology {ePrint} Archive, Paper 2024/637}, year = {2024}, url = {https://eprint.iacr.org/2024/637} } </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>