+
<html lang="en" dir="ltr">
+
<meta name="viewport" content="width=device-width,initial-scale=1">
+
<meta name="generator" content="Docusaurus v2.0.0-beta.17">
+
<link rel="alternate" type="application/rss+xml" href="/head-protocol/adr/rss.xml" title="Hydra: Head Protocol RSS Feed">
+
<link rel="alternate" type="application/atom+xml" href="/head-protocol/adr/atom.xml" title="Hydra: Head Protocol Atom Feed">
+
<link rel="search" type="application/opensearchdescription+xml" title="Hydra: Head Protocol" href="/head-protocol/opensearch.xml">
+
<link rel="alternate" type="application/rss+xml" href="/head-protocol/monthly/rss.xml" title="Hydra: Head Protocol RSS Feed">
+
<link rel="alternate" type="application/atom+xml" href="/head-protocol/monthly/atom.xml" title="Hydra: Head Protocol Atom Feed">
+
<script src="https://plausible.io/js/script.js" defer="defer" data-domain="hydra.family"></script><title data-rh="true">21. Bounded transaction validity on Hydra protocol transactions | Hydra: Head Protocol</title><meta data-rh="true" name="twitter:card" content="summary_large_image"><meta data-rh="true" property="og:url" content="https://input-output-hk.github.io/head-protocol/adr/21"><meta data-rh="true" name="docusaurus_locale" content="en"><meta data-rh="true" name="docusaurus_tag" content="default"><meta data-rh="true" name="docsearch:language" content="en"><meta data-rh="true" name="docsearch:docusaurus_tag" content="default"><meta data-rh="true" property="og:title" content="21. Bounded transaction validity on Hydra protocol transactions | Hydra: Head Protocol"><meta data-rh="true" name="description" content="Status"><meta data-rh="true" property="og:description" content="Status"><meta data-rh="true" property="og:type" content="article"><meta data-rh="true" property="article:published_time" content="2022-12-05T00:00:00.000Z"><meta data-rh="true" property="article:author" content="https://github.com/ch1bo,https://github.com/pgrange,https://github.com/ffakenz,https://github.com/abailly-iohk,https://github.com/v0d1ch"><meta data-rh="true" property="article:tag" content="Accepted"><link data-rh="true" rel="icon" href="/head-protocol/img/hydra.png"><link data-rh="true" rel="canonical" href="https://input-output-hk.github.io/head-protocol/adr/21"><link data-rh="true" rel="alternate" href="https://input-output-hk.github.io/head-protocol/adr/21" hreflang="en"><link data-rh="true" rel="alternate" href="https://input-output-hk.github.io/head-protocol/fr/adr/21" hreflang="fr"><link data-rh="true" rel="alternate" href="https://input-output-hk.github.io/head-protocol/ja/adr/21" hreflang="ja"><link data-rh="true" rel="alternate" href="https://input-output-hk.github.io/head-protocol/adr/21" hreflang="x-default"><link data-rh="true" rel="preconnect" href="https://YZTAF8IOVB-dsn.algolia.net" crossorigin="anonymous"><link rel="stylesheet" href="/head-protocol/assets/css/styles.44efd72d.css">
+
<link rel="preload" href="/head-protocol/assets/js/runtime~main.0e17bb85.js" as="script">
+
<link rel="preload" href="/head-protocol/assets/js/main.19b559a3.js" as="script">
+
<body class="navigation-with-keyboard">
+
<script>!function(){function t(t){document.documentElement.setAttribute("data-theme",t)}var e=function(){var t=null;try{t=localStorage.getItem("theme")}catch(t){}return t}();t(null!==e?e:"light")}()</script><div id="__docusaurus">
+
<div role="region"><a href="#" class="skipToContent_ZgBM">Skip to main content</a></div><nav class="navbar navbar--fixed-top"><div class="navbar__inner"><div class="navbar__items"><button aria-label="Navigation bar toggle" class="navbar__toggle clean-btn" type="button" tabindex="0"><svg width="30" height="30" viewBox="0 0 30 30" aria-hidden="true"><path stroke="currentColor" stroke-linecap="round" stroke-miterlimit="10" stroke-width="2" d="M4 7h22M4 15h22M4 23h22"></path></svg></button><a class="navbar__brand" href="/head-protocol/"><div class="navbar__logo"><img src="/head-protocol/img/hydra.png" alt="Hydra: Head Protocol" class="themedImage_W2Cr themedImage--light_TfLj"><img src="/head-protocol/img/hydra-white.png" alt="Hydra: Head Protocol" class="themedImage_W2Cr themedImage--dark_oUvU"></div><b class="navbar__title">Hydra: Head Protocol</b></a><a class="navbar__item navbar__link" href="/head-protocol/docs/getting-started">User Manual</a><a class="navbar__item navbar__link" href="/head-protocol/use-cases">Use Cases</a><a class="navbar__item navbar__link" href="/head-protocol/core-concepts">Core Concepts</a><a class="navbar__item navbar__link" href="/head-protocol/topologies">Topologies</a><a class="navbar__item navbar__link" href="/head-protocol/benchmarks">Benchmarks</a><a class="navbar__item navbar__link" href="/head-protocol/api-reference">API Reference</a></div><div class="navbar__items navbar__items--right"><a href="https://github.com/input-output-hk/hydra" target="_blank" rel="noopener noreferrer" class="navbar__item navbar__link"><span>GitHub<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_I5OW"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></span></a><div class="navbar__item dropdown dropdown--hoverable dropdown--right"><a href="#" class="navbar__link"><span><svg viewBox="0 0 24 24" width="20" height="20" aria-hidden="true" class="iconLanguage_dNtB"><path fill="currentColor" d="M12.87 15.07l-2.54-2.51.03-.03c1.74-1.94 2.98-4.17 3.71-6.53H17V4h-7V2H8v2H1v1.99h11.17C11.5 7.92 10.44 9.75 9 11.35 8.07 10.32 7.3 9.19 6.69 8h-2c.73 1.63 1.73 3.17 2.98 4.56l-5.09 5.02L4 19l5-5 3.11 3.11.76-2.04zM18.5 10h-2L12 22h2l1.12-3h4.75L21 22h2l-4.5-12zm-2.62 7l1.62-4.33L19.12 17h-3.24z"></path></svg><span>English</span></span></a><ul class="dropdown__menu"><li><a href="/head-protocol/adr/21" target="_self" rel="noopener noreferrer" class="dropdown__link dropdown__link--active">English</a></li><li><a href="/head-protocol/fr/adr/21" target="_self" rel="noopener noreferrer" class="dropdown__link">Français</a></li><li><a href="/head-protocol/ja/adr/21" target="_self" rel="noopener noreferrer" class="dropdown__link">日本語</a></li></ul></div><div class="toggle_S7eR toggle_TdHA toggleDisabled_f9M3"><div class="toggleButton_rCf9" role="button" tabindex="-1"><svg viewBox="0 0 24 24" width="24" height="24" class="lightToggleIcon_v35p"><path fill="currentColor" d="M12,9c1.65,0,3,1.35,3,3s-1.35,3-3,3s-3-1.35-3-3S10.35,9,12,9 M12,7c-2.76,0-5,2.24-5,5s2.24,5,5,5s5-2.24,5-5 S14.76,7,12,7L12,7z M2,13l2,0c0.55,0,1-0.45,1-1s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S1.45,13,2,13z M20,13l2,0c0.55,0,1-0.45,1-1 s-0.45-1-1-1l-2,0c-0.55,0-1,0.45-1,1S19.45,13,20,13z M11,2v2c0,0.55,0.45,1,1,1s1-0.45,1-1V2c0-0.55-0.45-1-1-1S11,1.45,11,2z M11,20v2c0,0.55,0.45,1,1,1s1-0.45,1-1v-2c0-0.55-0.45-1-1-1C11.45,19,11,19.45,11,20z M5.99,4.58c-0.39-0.39-1.03-0.39-1.41,0 c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0s0.39-1.03,0-1.41L5.99,4.58z M18.36,16.95 c-0.39-0.39-1.03-0.39-1.41,0c-0.39,0.39-0.39,1.03,0,1.41l1.06,1.06c0.39,0.39,1.03,0.39,1.41,0c0.39-0.39,0.39-1.03,0-1.41 L18.36,16.95z M19.42,5.99c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06c-0.39,0.39-0.39,1.03,0,1.41 s1.03,0.39,1.41,0L19.42,5.99z M7.05,18.36c0.39-0.39,0.39-1.03,0-1.41c-0.39-0.39-1.03-0.39-1.41,0l-1.06,1.06 c-0.39,0.39-0.39,1.03,0,1.41s1.03,0.39,1.41,0L7.05,18.36z"></path></svg><svg viewBox="0 0 24 24" width="24" height="24" class="darkToggleIcon_nQuB"><path fill="currentColor" d="M9.37,5.51C9.19,6.15,9.1,6.82,9.1,7.5c0,4.08,3.32,7.4,7.4,7.4c0.68,0,1.35-0.09,1.99-0.27C17.45,17.19,14.93,19,12,19 c-3.86,0-7-3.14-7-7C5,9.07,6.81,6.55,9.37,5.51z M12,3c-4.97,0-9,4.03-9,9s4.03,9,9,9s9-4.03,9-9c0-0.46-0.04-0.92-0.1-1.36 c-0.98,1.37-2.58,2.26-4.4,2.26c-2.98,0-5.4-2.42-5.4-5.4c0-1.81,0.89-3.42,2.26-4.4C12.92,3.04,12.46,3,12,3L12,3z"></path></svg></div><input type="checkbox" class="toggleScreenReader_g2nN" aria-label="Switch between dark and light mode (currently light mode)"></div><div class="searchBox_qEbK"><button type="button" class="DocSearch DocSearch-Button" aria-label="Search"><span class="DocSearch-Button-Container"><svg width="20" height="20" class="DocSearch-Search-Icon" viewBox="0 0 20 20"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.9418 2.9419-7.7115 2.9419-10.6533 0-2.9419-2.9418-2.9419-7.7115 0-10.6533 2.9418-2.9419 7.7115-2.9419 10.6533 0 2.9419 2.9418 2.9419 7.7115 0 10.6533z" stroke="currentColor" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round"></path></svg><span class="DocSearch-Button-Placeholder">Search</span></span><span class="DocSearch-Button-Keys"></span></button></div></div></div><div role="presentation" class="navbar-sidebar__backdrop"></div></nav><div class="main-wrapper blog-wrapper blog-post-page"><div class="container margin-vert--lg"><div class="row"><aside class="col col--3"><nav class="sidebar_a9qW thin-scrollbar" aria-label="Blog recent posts navigation"><div class="sidebarItemTitle_uKok margin-bottom--md">Architectural Decision Records</div><ul class="sidebarItemList_Kvuv"><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/1">1. Record Architecture Decisions
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/2">2. Reactive Core
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/3">3. Asynchronous Duplex Client API</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/4">4. Use Handle to model Effects
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/5">5. Use io-classes
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/6">6. Network Broadcasts all messages
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/7">7. Use with-pattern based component interfaces
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/8">8. Custom Prelude
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/9">9. Simplify Logging
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/10">10. Use Direct Connection to `cardano-node`
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/11">11. Use cardano-api
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/12">12. Top-down Test-driven Design
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/13">13. Plutus Contracts Testing Strategy
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/14">14. Token usage in Hydra Scripts
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/15">15. Configuration Through an Admin API
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/16">16. Keep Rejected ADRs
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/17">17. Use UDP protocol for Hydra networking
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/18">18. Single state in Hydra.Node.
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/19">19. Use of reference scripts
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/20">20. Handling time
+
</a></li><li class="sidebarItem_CF0Q"><a aria-current="page" class="sidebarItemLink_miNk sidebarItemLinkActive_RRTD" href="/head-protocol/adr/21">21. Bounded transaction validity on Hydra protocol transactions
+
</a></li><li class="sidebarItem_CF0Q"><a class="sidebarItemLink_miNk" href="/head-protocol/adr/22">22. Test High-level Properties using Model-Based Testing
+
</a></li></ul></nav></aside><main class="col col--7" itemscope="" itemtype="http://schema.org/Blog"><article itemprop="blogPost" itemscope="" itemtype="http://schema.org/BlogPosting"><header><h1 class="blogPostTitle_rzP5" itemprop="headline">21. Bounded transaction validity on Hydra protocol transactions
+
</h1><div class="blogPostData_Zg1s margin-vert--md"><time datetime="2022-12-05T00:00:00.000Z" itemprop="datePublished">December 5, 2022</time> · <!-- -->3 min read</div><div class="margin-top--md margin-bottom--sm row"><div class="col col--6 authorCol_FlmR"><div class="avatar margin-bottom--sm"><span class="avatar__photo-link avatar__photo"><a href="https://github.com/ch1bo" target="_blank" rel="noopener noreferrer"><img class="image_o0gy" src="https://github.com/ch1bo.png" alt="Sebastian Nagel"></a></span><div class="avatar__intro" itemprop="author" itemscope="" itemtype="https://schema.org/Person"><div class="avatar__name"><a href="https://github.com/ch1bo" target="_blank" rel="noopener noreferrer" itemprop="url"><span itemprop="name">Sebastian Nagel</span></a></div><small class="avatar__subtitle" itemprop="description">Software Engineering Lead - Hydra @ IOG</small></div></div></div><div class="col col--6 authorCol_FlmR"><div class="avatar margin-bottom--sm"><span class="avatar__photo-link avatar__photo"><a href="https://github.com/pgrange" target="_blank" rel="noopener noreferrer"><img class="image_o0gy" src="https://github.com/pgrange.png" alt="Pascal Grange"></a></span><div class="avatar__intro" itemprop="author" itemscope="" itemtype="https://schema.org/Person"><div class="avatar__name"><a href="https://github.com/pgrange" target="_blank" rel="noopener noreferrer" itemprop="url"><span itemprop="name">Pascal Grange</span></a></div><small class="avatar__subtitle" itemprop="description">Senior software engineer - Hydra @ IOG</small></div></div></div><div class="col col--6 authorCol_FlmR"><div class="avatar margin-bottom--sm"><span class="avatar__photo-link avatar__photo"><a href="https://github.com/ffakenz" target="_blank" rel="noopener noreferrer"><img class="image_o0gy" src="https://github.com/ffakenz.png" alt="Franco Testagrossa"></a></span><div class="avatar__intro" itemprop="author" itemscope="" itemtype="https://schema.org/Person"><div class="avatar__name"><a href="https://github.com/ffakenz" target="_blank" rel="noopener noreferrer" itemprop="url"><span itemprop="name">Franco Testagrossa</span></a></div><small class="avatar__subtitle" itemprop="description">Senior software engineer - Hydra @ IOG</small></div></div></div><div class="col col--6 authorCol_FlmR"><div class="avatar margin-bottom--sm"><span class="avatar__photo-link avatar__photo"><a href="https://github.com/abailly-iohk" target="_blank" rel="noopener noreferrer"><img class="image_o0gy" src="https://github.com/abailly-iohk.png" alt="Arnaud Bailly"></a></span><div class="avatar__intro" itemprop="author" itemscope="" itemtype="https://schema.org/Person"><div class="avatar__name"><a href="https://github.com/abailly-iohk" target="_blank" rel="noopener noreferrer" itemprop="url"><span itemprop="name">Arnaud Bailly</span></a></div><small class="avatar__subtitle" itemprop="description">Lead Architect - Hydra @ IOG</small></div></div></div><div class="col col--6 authorCol_FlmR"><div class="avatar margin-bottom--sm"><span class="avatar__photo-link avatar__photo"><a href="https://github.com/v0d1ch" target="_blank" rel="noopener noreferrer"><img class="image_o0gy" src="https://github.com/v0d1ch.png" alt="Sasha Bogicevic"></a></span><div class="avatar__intro" itemprop="author" itemscope="" itemtype="https://schema.org/Person"><div class="avatar__name"><a href="https://github.com/v0d1ch" target="_blank" rel="noopener noreferrer" itemprop="url"><span itemprop="name">Sasha Bogicevic</span></a></div><small class="avatar__subtitle" itemprop="description">Senior software engineer - Hydra @ IOG</small></div></div></div></div></header><div id="post-content" class="markdown" itemprop="articleBody"><h2 class="anchor anchorWithStickyNavbar_mojV" id="status">Status<a class="hash-link" href="#status" title="Direct link to heading"></a></h2><p>Proposed</p><h2 class="anchor anchorWithStickyNavbar_mojV" id="context">Context<a class="hash-link" href="#context" title="Direct link to heading"></a></h2><ul><li><p>The HydraHeadV1 formal specification contains a <em>bounded confirmation window</em>:</p><div class="codeBlockContainer_I0IT theme-code-block"><div class="codeBlockContent_wNvx"><pre tabindex="0" class="prism-code language-text codeBlock_jd64 thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token plain">// Deadline</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">T_max <= T_min + L // Bounded confirmation window</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">DL’ = T_max + L // The latest possible deadline is 2*L</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_wuS7 clean-btn">Copy</button></div></div><p>with <code>T_min</code> and <code>T_max</code> being the tx validity bounds and <code>L</code> being the
+
contestation period.</p><ul><li>This is to avoid attacks with specified upper validity bound being too far
+
in the future and denial of service the head with this (e.g. 10 years).</li></ul></li></ul><h4 class="anchor anchorWithStickyNavbar_mojV" id="current-state-of-things">Current state of things:<a class="hash-link" href="#current-state-of-things" title="Direct link to heading"></a></h4><ul><li><p>The contestation period and upper tx validity is used for computing the
+
contestation deadline.</p></li><li><p>There is a <code>closeGraceTime</code> currently hard-coded (to <code>100</code> slots) to set some
+
upper bound on the <code>closeTx</code>. This was also required so far to compute the
+
contestation deadline.</p></li><li><p>Different networks (chains) have different slot lenghts, e.g. the preview
+
network has a slot every <code>1s</code>, while our local devnets use <code>0.1s</code>. This means
+
hardcoded values like <code>closeGraceTime</code> need to be <em>in sync</em> with the
+
underlying network.</p></li><li><p>The <code>contestationPeriod</code> can be configured by users via the <code>Init</code> client
+
input. For example, the hydra-cluster test suite uses a hardcoded <code>cperiod</code> on
+
the client side.</p></li><li><p>Default value for <code>T_Min</code> is negative infinity.</p></li><li><p>Lower tx validity being in the future does not pose a problem since other
+
participant is able to close a head.</p></li></ul><h4 class="anchor anchorWithStickyNavbar_mojV" id="what-we-want-to-achieve">What we want to achieve:<a class="hash-link" href="#what-we-want-to-achieve" title="Direct link to heading"></a></h4><ul class="contains-task-list"><li><p>We want to enforce topmost formula in this file in our code on-chain.</p></li><li><p>Introduce <code>maxGraceTime</code> expressed in seconds in place of <code>closeGraceTime</code> and adjust to
+
appropriate value.</p></li><li><p>The contestation period is to be used to create bounded close transaction
+
(together with <code>maxGraceTime</code>). Before it was only used for computing the
+
contestation deadline.</p></li><li class="task-list-item"><p><input type="checkbox" checked="" disabled=""> <!-- -->If contestation period is higher than <code>maxGraceTime</code> we will pick the
+
latter. We still need <code>maxGraceTime</code> since if <code>contestationPeriod</code> is low for
+
the current network our txs reach the upper bound fast and become invalid.
+
That is why we set the upper tx bound to be minimum between
+
<code>contestationPeriod</code> and <code>maxGraceTime</code> so that txs have high enough upper
+
bound.</p></li><li><p>Make sure all head participants use the same value for <code>contestationPeriod</code>.</p></li><li><p>Attack vector has a corresponding mutation test.</p></li></ul><h2 class="anchor anchorWithStickyNavbar_mojV" id="decision">Decision<a class="hash-link" href="#decision" title="Direct link to heading"></a></h2><ul><li><p>Use the specification formula on-chain.</p></li><li><p>Configure the contestation period (number of seconds) on the <code>hydra-node</code>,
+
e.g. via a <code>--contestation-period</code> command line option.</p></li><li><p>Lower tx bound should be the last known slot as reported by the
+
<code>cardano-node</code>.</p></li><li><p>Upper tx bound is the current time + minimum between <code>contestationPeriod</code> and
+
<code>maxGraceTime</code>.</p></li><li><p>When submitting the <code>InitTx</code> make sure to use <code>--contestation-period</code> value
+
from our node's flag.</p></li><li><p>If other nodes observe <code>OnInitTx</code> and the <code>contestationPeriod</code> value does not
+
match with their <code>--contestation-period</code> setting - ignore <code>InitTx</code>.</p></li><li><p>Rename <code>closeGraceTime</code> to <code>maxGraceTime</code> since we are using it also for upper
+
bound of a contest tx.</p></li></ul><h2 class="anchor anchorWithStickyNavbar_mojV" id="consequences">Consequences<a class="hash-link" href="#consequences" title="Direct link to heading"></a></h2><ul><li><p>Not any positive number of seconds is a valid contestation period any more!</p></li><li><p>Upper tx validity of close transaction is the minimum between <code>maxGraceTime</code>
+
and <code>contestationPeriod</code> and this needs to be <em>good enough</em> value with respect
+
to running network. This is a consequence required by the ledger when
+
constructing transactions since we cannot convert arbitrary point in times to
+
slots.</p></li><li><p>All parties need to aggree on contestation period before trying to run a Head
+
protocol otherwise InitTx will be ignored.</p></li></ul></div><footer class="row docusaurus-mt-lg blogPostDetailsFull_h6_j"><div class="col"><b>Tags:</b><ul class="tags_XVD_ padding--none margin-left--sm"><li class="tag_JSN8"><a class="tag_hD8n tagRegular_D6E_" href="/head-protocol/adr/tags/accepted">Accepted</a></li></ul></div></footer></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Blog post page navigation"><div class="pagination-nav__item"><a class="pagination-nav__link" href="/head-protocol/adr/20"><div class="pagination-nav__sublabel">Newer Post</div><div class="pagination-nav__label">20. Handling time
+
</div></a></div><div class="pagination-nav__item pagination-nav__item--next"><a class="pagination-nav__link" href="/head-protocol/adr/22"><div class="pagination-nav__sublabel">Older Post</div><div class="pagination-nav__label">22. Test High-level Properties using Model-Based Testing
+
</div></a></div></nav></main><div class="col col--2"><div class="tableOfContents_cNA8 thin-scrollbar"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#status" class="table-of-contents__link toc-highlight">Status</a></li><li><a href="#context" class="table-of-contents__link toc-highlight">Context</a></li><li><a href="#decision" class="table-of-contents__link toc-highlight">Decision</a></li><li><a href="#consequences" class="table-of-contents__link toc-highlight">Consequences</a></li></ul></div></div></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Contributing</div><ul class="footer__items"><li class="footer__item"><a href="https://github.com/input-output-hk/hydra/wiki/Coding-Standards" target="_blank" rel="noopener noreferrer" class="footer__link-item">Coding Standards</a></li><li class="footer__item"><a class="footer__link-item" href="/head-protocol/adr">Architectural Decision Records</a></li><li class="footer__item"><a href="https://github.com/input-output-hk/hydra/wiki/Testing-Strategy" target="_blank" rel="noopener noreferrer" class="footer__link-item">Testing Strategy</a></li></ul></div><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items"><li class="footer__item"><a href="https://discord.gg/Qq5vNTg9PT" target="_blank" rel="noopener noreferrer" class="footer__link-item"><span>Discord (#ask-hydra)<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_I5OW"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></span></a></li><li class="footer__item"><a href="https://github.com/input-output-hk/hydra/discussions" target="_blank" rel="noopener noreferrer" class="footer__link-item"><span>Github Discussions<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_I5OW"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></span></a></li><li class="footer__item"><a href="https://cardano.stackexchange.com/questions/tagged/hydra" target="_blank" rel="noopener noreferrer" class="footer__link-item"><span>Stack Exchange<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_I5OW"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></span></a></li></ul></div><div class="col footer__col"><div class="footer__title">More</div><ul class="footer__items"><li class="footer__item"><a class="footer__link-item" href="/head-protocol/docs/haskell_packages">Haskell Packages</a></li><li class="footer__item"><a class="footer__link-item" href="/head-protocol/monthly">Monthly reports</a></li><li class="footer__item"><a href="https://github.com/input-output-hk/hydra/wiki/Logbook" target="_blank" rel="noopener noreferrer" class="footer__link-item">Logbook</a></li></ul></div><div class="col footer__col"><div class="footer__title">Legal</div><ul class="footer__items"><li class="footer__item"><a href="https://static.iohk.io/terms/iohktermsandconditions.pdf" target="_blank" rel="noopener noreferrer" class="footer__link-item">Terms & Conditions</a></li><li class="footer__item"><a href="https://static.iohk.io/terms/iog-privacy-policy.pdf" target="_blank" rel="noopener noreferrer" class="footer__link-item">Privacy Policy</a></li><li class="footer__item"><a href="https://github.com/input-output-hk/hydra/graphs/contributors" target="_blank" rel="noopener noreferrer" class="footer__link-item">Contributors</a></li></ul></div></div><div class="footer__bottom text--center"><div class="footer__copyright">
+
Built with Docusaurus on 2023-03-07T20:06:36+01:00
+
</div></div></div></footer></div>
+
<script src="/head-protocol/assets/js/runtime~main.0e17bb85.js"></script>
+
<script src="/head-protocol/assets/js/main.19b559a3.js"></script>
\ No newline at end of file
![dependabot[bot]](https://avatars.githubusercontent.com/in/29110?v=4&s=80)
