Example 016 in TCPDF Library

Question

I'm trying to create a simple pdf using self-signed signature encryption method in php with tcpdf and open that pdf threw digital ID.

I'm running example 016 in TCPDF library but an error occurred, when I opened the PDF with Acrobat Reader with installing .p12 certificate. :

"File Type Error"

My code is look like this:

   $pdf->SetProtection($permissions=array('print','copy','owner'),$user_pass='', $owner_pass=null, $mode=1,$pubkeys=array(array('c' =>'file://data/cert/test.crt', 'p' => array('print', 'copy','owner'))));