                        const OSSL_PARAM params[],
                                        void *arg);</code></pre>

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

<p>For certain events or activities, provider functionality may need help from the application or the calling OpenSSL libraries themselves. For example, user input or direct (possibly optional) user output could be implemented this way.</p>

<p>Callback functions themselves are always provided by or through the calling OpenSSL libraries, along with a gen