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<title>EVP_MAC-GMAC</title>
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<ul id="index">
<li><a href="#NAME">NAME</a></li>
<li><a href="#DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#Identity">Identity</a></li>
<li><a href="#Supported-parameters">Supported parameters</a></li>
</ul>
</li>
<li><a href="#SEE-ALSO">SEE ALSO</a></li>
<li><a href="#COPYRIGHT">COPYRIGHT</a></li>
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<h1 id="NAME">NAME</h1>
<p>EVP_MAC-GMAC - The GMAC EVP_MAC implementation</p>
<h1 id="DESCRIPTION">DESCRIPTION</h1>
<p>Support for computing GMAC MACs through the <b>EVP_MAC</b> API.</p>
<p>This implementation uses EVP_CIPHER functions to get access to the underlying cipher.</p>
<h2 id="Identity">Identity</h2>
<p>This implementation is identified with this name and properties, to be used with EVP_MAC_fetch():</p>
<dl>
<dt id="GMAC-provider-default-or-provider-fips">"GMAC", "provider=default" or "provider=fips"</dt>
<dd>
</dd>
</dl>
<h2 id="Supported-parameters">Supported parameters</h2>
<p>The general description of these parameters can be found in <a href="../man3/EVP_MAC.html">"PARAMETERS" in EVP_MAC(3)</a>.</p>
<p>The following parameter can be set with EVP_MAC_CTX_set_params():</p>
<dl>
<dt id="key-OSSL_MAC_PARAM_KEY-octet-string">"key" (<b>OSSL_MAC_PARAM_KEY</b>) <octet string></dt>
<dd>
<p>Sets the MAC key. Setting this parameter is identical to passing a <i>key</i> to <a href="../man3/EVP_MAC_init.html">EVP_MAC_init(3)</a>.</p>
</dd>
<dt id="iv-OSSL_MAC_PARAM_IV-octet-string">"iv" (<b>OSSL_MAC_PARAM_IV</b>) <octet string></dt>
<dd>
<p>Sets the IV of the underlying cipher, when applicable.</p>
</dd>
<dt id="cipher-OSSL_MAC_PARAM_CIPHER-UTF8-string">"cipher" (<b>OSSL_MAC_PARAM_CIPHER</b>) <UTF8 string></dt>
<dd>
<p>Sets the name of the underlying cipher to be used.</p>
</dd>
<dt id="properties-OSSL_MAC_PARAM_PROPERTIES-UTF8-string">"properties" (<b>OSSL_MAC_PARAM_PROPERTIES</b>) <UTF8 string></dt>
<dd>
<p>Sets the properties to be queried when trying to fetch the underlying cipher. This must be given together with the cipher naming parameter to be considered valid.</p>
</dd>
</dl>
<p>The following parameters can be retrieved with EVP_MAC_CTX_get_params():</p>
<dl>
<dt id="size-OSSL_MAC_PARAM_SIZE-unsigned-integer">"size" (<b>OSSL_MAC_PARAM_SIZE</b>) <unsigned integer></dt>
<dd>
<p>Gets the MAC size.</p>
</dd>
</dl>
<p>The "size" parameter can also be retrieved with EVP_MAC_CTX_get_mac_size(). The length of the "size" parameter is equal to that of an <b>unsigned int</b>.</p>
<h1 id="SEE-ALSO">SEE ALSO</h1>
<p><a href="../man3/EVP_MAC_CTX_get_params.html">EVP_MAC_CTX_get_params(3)</a>, <a href="../man3/EVP_MAC_CTX_set_params.html">EVP_MAC_CTX_set_params(3)</a>, <a href="../man3/EVP_MAC.html">"PARAMETERS" in EVP_MAC(3)</a>, <a href="../man3/OSSL_PARAM.html">OSSL_PARAM(3)</a></p>
<h1 id="COPYRIGHT">COPYRIGHT</h1>
<p>Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>Licensed under the Apache License 2.0 (the "License"). 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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