 it wants or is expected to pass back, and pass that as <i>params</i>, as well as the opaque data pointer it received, as <i>arg</i>.</p>

</dd>
<dt id="OSSL_PASSPHRASE_CALLBACK"><b>OSSL_PASSPHRASE_CALLBACK</b></dt>
<dd>

<p>This is a specialised callback function, used specifically to prompt the user for a passphrase. When calling this callback function, a buffer to store the pass phrase needs to be given with <i>pass</i>, and its size with <i>pass_size</i>. The length of the prompted pass phrase will be g