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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Utilities to safely compare cryptographic values."><title>openssl::memcmp - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="openssl" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">Module memcmp</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../openssl/index.html">openssl</a><span class="version">0.10.75</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">Module memcmp</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul><h3><a href="#functions">Module Items</a></h3><ul class="block"><li><a href="#functions" title="Functions">Functions</a></li></ul></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="../index.html">In crate openssl</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../index.html">openssl</a></div><h1>Module <span>memcmp</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../src/openssl/memcmp.rs.html#1-93">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Utilities to safely compare cryptographic values.</p>
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<p>Extra care must be taken when comparing values in
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cryptographic code. If done incorrectly, it can lead
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to a <a href="https://en.wikipedia.org/wiki/Timing_attack">timing attack</a>.
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By analyzing the time taken to execute parts of a cryptographic
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algorithm, and attacker can attempt to compromise the
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cryptosystem.</p>
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<p>The utilities in this module are designed to be resistant
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to this type of attack.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>To perform a constant-time comparison of two arrays of the same length but different
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values:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>openssl::memcmp::eq;
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<span class="comment">// We want to compare `a` to `b` and `c`, without giving
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// away through timing analysis that `c` is more similar to `a`
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// than `b`.
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</span><span class="kw">let </span>a = [<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>];
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<span class="kw">let </span>b = [<span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>];
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<span class="kw">let </span>c = [<span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>];
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<span class="comment">// These statements will execute in the same amount of time.
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</span><span class="macro">assert!</span>(!eq(<span class="kw-2">&</span>a, <span class="kw-2">&</span>b));
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<span class="macro">assert!</span>(!eq(<span class="kw-2">&</span>a, <span class="kw-2">&</span>c));</code></pre></div></div></details><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><dl class="item-table"><dt><a class="fn" href="fn.eq.html" title="fn openssl::memcmp::eq">eq</a></dt><dd>Returns <code>true</code> iff <code>a</code> and <code>b</code> contain the same bytes.</dd></dl></section></div></main></body></html> |