mirror of
https://github.com/semaphore-protocol/semaphore.git
synced 2026-04-28 03:00:41 -04:00
383 lines
21 KiB
HTML
383 lines
21 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js light">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>libsemaphore - </title>
|
|
|
|
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|
<meta name="description" content="">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff" />
|
|
|
|
<link rel="shortcut icon" href="favicon.png">
|
|
<link rel="stylesheet" href="css/variables.css">
|
|
<link rel="stylesheet" href="css/general.css">
|
|
<link rel="stylesheet" href="css/chrome.css">
|
|
<link rel="stylesheet" href="css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
|
|
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css">
|
|
<link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="highlight.css">
|
|
<link rel="stylesheet" href="tomorrow-night.css">
|
|
<link rel="stylesheet" href="ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
|
|
|
|
</head>
|
|
<body>
|
|
<!-- Provide site root to javascript -->
|
|
<script type="text/javascript">
|
|
var path_to_root = "";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
|
|
</script>
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script type="text/javascript">
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script type="text/javascript">
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
var html = document.querySelector('html');
|
|
html.classList.remove('no-js')
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add('js');
|
|
</script>
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script type="text/javascript">
|
|
var html = document.querySelector('html');
|
|
var sidebar = 'hidden';
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
}
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div id="sidebar-scrollbox" class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="expanded "><a href="about.html"><strong aria-hidden="true">1.</strong> About</a></li><li class="expanded "><a href="howitworks.html"><strong aria-hidden="true">2.</strong> How it works</a></li><li class="expanded "><a href="quickstart.html"><strong aria-hidden="true">3.</strong> Quick start</a></li><li class="expanded "><a href="usage.html"><strong aria-hidden="true">4.</strong> Usage</a></li><li class="expanded "><a href="api.html"><strong aria-hidden="true">5.</strong> Contract API</a></li><li class="expanded "><a href="libsemaphore.html" class="active"><strong aria-hidden="true">6.</strong> libsemaphore</a></li><li class="expanded "><a href="trustedsetup.html"><strong aria-hidden="true">7.</strong> Trusted setup</a></li><li class="expanded "><a href="audit.html"><strong aria-hidden="true">8.</strong> Security audit</a></li><li class="expanded "><a href="creditsandresources.html"><strong aria-hidden="true">9.</strong> Credits and resources</a></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
|
|
<div id="menu-bar" class="menu-bar">
|
|
<div id="menu-bar-sticky-container">
|
|
<div class="left-buttons">
|
|
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</button>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
|
|
</div>
|
|
|
|
<h1 class="menu-title"></h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script type="text/javascript">
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1><a class="header" href="#libsemaphore" id="libsemaphore">libsemaphore</a></h1>
|
|
<p><a href="https://www.npmjs.com/package/libsemaphore"><code>libsemaphore</code></a> is a helper
|
|
library for Semaphore written in Typescript. Any dApp written in Javascript or
|
|
Typescript should use it as it provides useful abstractions over common tasks
|
|
and objects, such as identities and proof generation.</p>
|
|
<p>Note that only v1.0.14 and above works with the Semaphore code in this
|
|
repository. v0.0.x is compatible with the pre-audited Semaphore code.</p>
|
|
<h2><a class="header" href="#available-types-interfaces-and-functions" id="available-types-interfaces-and-functions">Available types, interfaces, and functions</a></h2>
|
|
<h3><a class="header" href="#types" id="types">Types</a></h3>
|
|
<p><strong><code>SnarkBigInt</code></strong></p>
|
|
<p>A big integer type compatible with the <code>snarkjs</code> library. Note that it is not
|
|
advisable to mix variables of this type with <code>bigNumber</code>s or <code>BigInt</code>s.
|
|
Encapsulates <code>snarkjs.bigInt</code>.</p>
|
|
<p><strong><code>EddsaPrivateKey</code></strong></p>
|
|
<p>An <a href="https://tools.ietf.org/html/rfc8032">EdDSA</a> private key which should be 32
|
|
bytes long. Encapsulates a <a href="https://nodejs.org/api/buffer.html"><code>Buffer</code></a>.</p>
|
|
<p><strong><code>EddsaPublicKey</code></strong></p>
|
|
<p>An EdDSA public key. Encapsulates an array of <code>SnarkBigInt</code>s.</p>
|
|
<p><strong><code>SnarkProvingKey</code></strong></p>
|
|
<p>A proving key, which when used with a secret <em>witness</em>, generates a zk-SNARK
|
|
proof about said witness. Encapsulates a <code>Buffer</code>.</p>
|
|
<p><strong><code>SnarkVerifyingKey</code></strong></p>
|
|
<p>A verifying key which when used with public inputs to a zk-SNARK and a
|
|
<code>SnarkProof</code>, can prove the proof's validity. Encapsulates a <code>Buffer</code>.</p>
|
|
<p><strong><code>SnarkWitness</code></strong></p>
|
|
<p>The secret inputs to a zk-SNARK. Encapsulates an array of <code>SnarkBigInt</code>s.</p>
|
|
<p><strong><code>SnarkPublicSignals</code></strong></p>
|
|
<p>The public inputs to a zk-SNARK. Encapsulates an array of <code>SnarkBigInt</code>s.</p>
|
|
<h3><a class="header" href="#interfaces" id="interfaces">Interfaces</a></h3>
|
|
<p><strong><code>EddsaKeyPair</code></strong></p>
|
|
<p>Encapsulates an <code>EddsaPublicKey</code> and an <code>EddsaPrivateKey</code>.</p>
|
|
<pre><code class="language-ts">interface EddsaKeyPair {
|
|
pubKey: EddsaPublicKey,
|
|
privKey: EddsaPrivateKey,
|
|
}
|
|
</code></pre>
|
|
<p><strong><code>Identity</code></strong></p>
|
|
<p>Encapsulates all information required to generate an identity commitment, and
|
|
is crucial to creating <code>SnarkProof</code>s to broadcast signals.</p>
|
|
<pre><code class="language-ts">interface Identity {
|
|
keypair: EddsaKeyPair,
|
|
identityNullifier: SnarkBigInt,
|
|
identityTrapdoor: SnarkBigInt,
|
|
}
|
|
</code></pre>
|
|
<p><strong><code>SnarkProof</code></strong></p>
|
|
<p>Note that <code>broadcastSignal()</code> accepts a <code>uint256[8]</code> array for its <code>_proof</code>
|
|
parameter. See <code>genBroadcastSignalParams()</code>.</p>
|
|
<pre><code class="language-ts">interface SnarkProof {
|
|
pi_a: SnarkBigInt[]
|
|
pi_b: SnarkBigInt[][]
|
|
pi_c: SnarkBigInt[]
|
|
}
|
|
</code></pre>
|
|
<h3><a class="header" href="#functions" id="functions">Functions</a></h3>
|
|
<p><strong><code>genPubKey(privKey: EddsaPrivateKey): EddsaPublicKey</code></strong></p>
|
|
<p>Generates a public EdDSA key from a supplied private key. To generate a private
|
|
key, use <code>crypto.randomBytes(32)</code> where <code>crypto</code> is the built-in Node or
|
|
browser module.</p>
|
|
<p><strong><code>genIdentity(): Identity</code></strong></p>
|
|
<p>This is a convenience function to generate a fresh and random <code>Identity</code>. That
|
|
is, the 32-byte private key for the <code>EddsaKeyPair</code> is randomly generated, as
|
|
are the distinct 31-byte identity nullifier and the 31-byte identity trapdoor
|
|
values.</p>
|
|
<p><strong><code>serialiseIdentity(identity: Identity): string</code></strong></p>
|
|
<p>Converts an <code>Identity</code> into a JSON string which looks like this:</p>
|
|
<pre><code class="language-text">["e82cc2b8654705e427df423c6300307a873a2e637028fab3163cf95b18bb172e","a02e517dfb3a4184adaa951d02bfe0fe092d1ee34438721d798db75b8db083","15c6540bf7bddb0616984fccda7e954a0fb5ea4679ac686509dc4bd7ba9c3b"]
|
|
</code></pre>
|
|
<p>You can also spell this function as <code>serializeIdentity</code>.</p>
|
|
<p>To convert this string back into an <code>Identity</code>, use <code>unSerialiseIdentity()</code>.</p>
|
|
<p><strong><code>unSerialiseIdentity(string: serialisedId): Identity</code></strong></p>
|
|
<p>Converts the <code>string</code> output of <code>serialiseIdentity()</code> to an <code>Identity</code>.</p>
|
|
<p>You can also spell this function as <code>unSerializeIdentity</code>.</p>
|
|
<p><strong><code>genIdentityCommitment(identity: Identity): SnarkBigInt</code></strong></p>
|
|
<p>Generates an identity commitment, which is the hash of the public key, the
|
|
identity nullifier, and the identity trapdoor.</p>
|
|
<p><strong><code>async genProof(witness: SnarkWitness, provingKey: SnarkProvingKey): SnarkProof</code></strong></p>
|
|
<p>Generates a <code>SnarkProof</code>, which can be sent to the Semaphore contract's
|
|
<code>broadcastSignal()</code> function. It can also be verified off-chain using
|
|
<code>verifyProof()</code> below.</p>
|
|
<p><strong><code>genPublicSignals(witness: SnarkWitness, circuit: SnarkCircuit): SnarkPublicSignals</code></strong></p>
|
|
<p>Extracts the public signals to be supplied to the contract or <code>verifyProof()</code>.</p>
|
|
<p><strong><code>verifyProof(verifyingKey: SnarkVerifyingKey, proof: SnarkProof, publicSignals: SnarkPublicSignals): boolean</code></strong></p>
|
|
<p>Returns <code>true</code> if the given <code>proof</code> is valid, given the correct verifying key
|
|
and public signals.</p>
|
|
<p>Returns <code>false</code> otherwise.</p>
|
|
<p><strong><code>signMsg(privKey: EddsaPrivateKey, msg: SnarkBigInt): EdDSAMiMcSpongeSignature)</code></strong></p>
|
|
<p>Encapsualtes <code>circomlib.eddsa.signMiMCSponge</code> to sign a message <code>msg</code> using private key <code>privKey</code>.</p>
|
|
<p><strong><code>verifySignature(msg: SnarkBigInt, signature: EdDSAMiMcSpongeSignature, pubKey: EddsaPublicKey)</code>: boolean</strong></p>
|
|
<p>Returns <code>true</code> if the cryptographic <code>signature</code> of the signed <code>msg</code> is from the
|
|
private key associated with <code>pubKey</code>.</p>
|
|
<p>Returns <code>false</code> otherwise.</p>
|
|
<p><strong><code>setupTree(levels: number, prefix: string): MerkleTree</code></strong></p>
|
|
<p>Returns a Merkle tree created using
|
|
<a href="https://www.npmjs.com/package/semaphore-merkle-tree"><code>semaphore-merkle-tree</code></a>
|
|
with the same number of levels which the Semaphore zk-SNARK circuit expects.
|
|
This tree is also configured to use <code>MimcSpongeHasher</code>, which is also what the
|
|
circuit expects.</p>
|
|
<p><code>levels</code> sets the number of levels of the tree. A tree with 20 levels, for
|
|
instance, supports up to 1048576 deposits.</p>
|
|
<p><strong><code>genCircuit(circuitDefinition: any)</code></strong></p>
|
|
<p>Returns a <code>new snarkjs.Circuit(circuitDefinition)</code>. The <code>circuitDefinition</code>
|
|
object should be the <code>JSON.parse</code>d result of the <code>circom</code> command which
|
|
converts a <code>.circom</code> file to a <code>.json</code> file.</p>
|
|
<p><strong><code>async genWitness(...)</code></strong></p>
|
|
<p>This function has the following signature:</p>
|
|
<pre><code class="language-ts">const genWitness = async (
|
|
signal: string,
|
|
circuit: SnarkCircuit,
|
|
identity: Identity,
|
|
idCommitments: SnarkBigInt[] | BigInt[] | ethers.utils.BigNumber[],
|
|
treeDepth: number,
|
|
externalNullifier: SnarkBigInt,
|
|
)
|
|
</code></pre>
|
|
<ul>
|
|
<li><code>signal</code> is the string you wish to broadcast.</li>
|
|
<li><code>circuit</code> is the output of <code>genCircuit()</code>.</li>
|
|
<li><code>identity</code> is the <code>Identity</code> whose identity commitment you want to prove is
|
|
in the set of registered identities.</li>
|
|
<li><code>idCommitments</code> is an array of registered identity commmitments; i.e. the
|
|
leaves of the tree.</li>
|
|
<li><code>treeDepth</code> is the number of levels which the Merkle tree used has</li>
|
|
<li><code>externalNullifier</code> is the current external nullifier</li>
|
|
</ul>
|
|
<p>It returns an object as such:</p>
|
|
<ul>
|
|
<li><code>witness</code>: The witness to pass to <code>genProof()</code>.</li>
|
|
<li><code>signal</code>: The computed signal for Semaphore. This is the hash of the
|
|
recipient's address, relayer's address, and fee.</li>
|
|
<li><code>signalHash</code>: The hash of the computed signal.</li>
|
|
<li><code>msg</code>: The hash of the external nullifier and the signal hash</li>
|
|
<li><code>signature</code>: The signature on the above msg.</li>
|
|
<li><code>tree</code>: The Merkle tree object after it has been updated with the identity commitment</li>
|
|
<li><code>identityPath</code>: The Merkle path to the identity commmitment</li>
|
|
<li><code>identityPathIndex</code>: The leaf index of the identity commitment</li>
|
|
<li><code>identityPathElements</code>: The elements along the above Merkle path</li>
|
|
</ul>
|
|
<p>Only <code>witness</code> is essential to generate the proof; the other data is only
|
|
useful for debugging and additional off-chain checks, such as verifying the
|
|
signature and the Merkle tree root.</p>
|
|
<p><strong><code>formatForVerifierContract = (proof: SnarkProof, publicSignals: SnarkPublicSignals</code></strong></p>
|
|
<p>Converts the data in <code>proof</code> and <code>publicSignals</code> to strings and rearranges
|
|
elements of <code>proof.pi_b</code> so that <code>snarkjs</code>'s <code>verifier.sol</code> will accept it.
|
|
To be specific, it returns an object as such:</p>
|
|
<pre><code class="language-ts">{
|
|
a: [ proof.pi_a[0].toString(), proof.pi_a[1].toString() ],
|
|
b: [
|
|
[ proof.pi_b[0][1].toString(), proof.pi_b[0][0].toString() ],
|
|
[ proof.pi_b[1][1].toString(), proof.pi_b[1][0].toString() ],
|
|
],
|
|
c: [ proof.pi_c[0].toString(), proof.pi_c[1].toString() ],
|
|
input: publicSignals.map((x) => x.toString()),
|
|
}
|
|
</code></pre>
|
|
<p><strong><code>stringifyBigInts = (obj: any) => object</code></strong></p>
|
|
<p>Encapsulates <code>snarkjs.stringifyBigInts()</code>. Makes it easy to convert <code>SnarkProof</code>s to JSON. </p>
|
|
<p><strong><code>unstringifyBigInts = (obj: any) => object</code></strong></p>
|
|
<p>Encapsulates <code>snarkjs.unstringifyBigInts()</code>. Makes it easy to convert JSON to <code>SnarkProof</code>s.</p>
|
|
<p><strong><code>genExternalNullifier = (plaintext: string) => string</code></strong></p>
|
|
<p>Each external nullifier must be at most 29 bytes large. This function
|
|
keccak-256-hashes a given <code>plaintext</code>, takes the last 29 bytes, and pads it
|
|
(from the start) with 0s, and returns the resulting hex string.</p>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="prev" href="api.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a rel="next" href="trustedsetup.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
|
<a href="api.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a href="trustedsetup.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<script type="text/javascript">
|
|
window.playpen_copyable = true;
|
|
</script>
|
|
|
|
|
|
|
|
|
|
|
|
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
|
|
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="book.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|