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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
  <li><a href="#OPTIONS">OPTIONS</a></li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#HISTORY">HISTORY</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>openssl-rand - generate pseudo-random bytes</p>

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<p><b>openssl rand</b> [<b>-help</b>] [<b>-out</b> <i>file</i>] [<b>-base64</b>] [<b>-hex</b>] [<b>-engine</b> <i>id</i>] [<b>-rand</b> <i>files</i>] [<b>-writerand</b> <i>file</i>] [<b>-provider</b> <i>name</i>] [<b>-provider-path</b> <i>path</i>] [<b>-provparam</b> <i>[name:]key=value</i>] [<b>-propquery</b> <i>propq</i>] <i>num</i>[K|M|G|T]</p>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>This command generates <i>num</i> random bytes using a cryptographically secure pseudo random number generator (CSPRNG). A suffix [K|M|G|T] may be appended to the num value to indicate the requested value be scaled as a multiple of KiB/MiB/GiB/TiB respectively. Note that suffixes are case sensitive, and that the suffixes represent binary multiples (K = 1024 bytes, M = 1024*1024 bytes, etc).</p>

<p>The string &#39;max&#39; may be substituted for a numerical value in num, to request the maximum number of bytes the CSPRNG can produce per instantiation. Currently, this is restricted to 2^61 bytes as per NIST SP 800-90C.</p>

<p>The random bytes are generated using the <a href="../man3/RAND_bytes.html">RAND_bytes(3)</a> function, which provides a security level of 256 bits, provided it managed to seed itself successfully from a trusted operating system entropy source. Otherwise, the command will fail with a nonzero error code. For more details, see <a href="../man3/RAND_bytes.html">RAND_bytes(3)</a>, <a href="../man7/RAND.html">RAND(7)</a>, and <a href="../man7/EVP_RAND.html">EVP_RAND(7)</a>.</p>

<h1 id="OPTIONS">OPTIONS</h1>

<dl>

<dt id="help"><b>-help</b></dt>
<dd>

<p>Print out a usage message.</p>

</dd>
<dt id="out-file"><b>-out</b> <i>file</i></dt>
<dd>

<p>Write to <i>file</i> instead of standard output.</p>

</dd>
<dt id="base64"><b>-base64</b></dt>
<dd>

<p>Perform base64 encoding on the output.</p>

</dd>
<dt id="hex"><b>-hex</b></dt>
<dd>

<p>Show the output as a hex string.</p>

</dd>
<dt id="engine-id"><b>-engine</b> <i>id</i></dt>
<dd>

<p>See <a href="../man1/openssl.html">&quot;Engine Options&quot; in openssl(1)</a>. This option is deprecated.</p>

</dd>
<dt id="rand-files--writerand-file"><b>-rand</b> <i>files</i>, <b>-writerand</b> <i>file</i></dt>
<dd>

<p>See <a href="../man1/openssl.html">&quot;Random State Options&quot; in openssl(1)</a> for details.</p>

</dd>
<dt id="provider-name"><b>-provider</b> <i>name</i></dt>
<dd>

</dd>
<dt id="provider-path-path"><b>-provider-path</b> <i>path</i></dt>
<dd>

</dd>
<dt id="provparam-name:-key-value"><b>-provparam</b> <i>[name:]key=value</i></dt>
<dd>

</dd>
<dt id="propquery-propq"><b>-propquery</b> <i>propq</i></dt>
<dd>

<p>See <a href="../man1/openssl.html">&quot;Provider Options&quot; in openssl(1)</a>, <a href="../man7/provider.html">provider(7)</a>, and <a href="../man7/property.html">property(7)</a>.</p>

</dd>
</dl>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man1/openssl.html">openssl(1)</a>, <a href="../man3/RAND_bytes.html">RAND_bytes(3)</a>, <a href="../man7/RAND.html">RAND(7)</a>, <a href="../man7/EVP_RAND.html">EVP_RAND(7)</a></p>

<h1 id="HISTORY">HISTORY</h1>

<p>The <b>-engine</b> option was deprecated in OpenSSL 3.0.</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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