Password Protecting PDFs using PHP

example.php

<?php
require "PasswordProtectPDF.php";

try {
    $pdf = new PasswordProtectPDF("test.pdf", "mypassword");
    // render the PDF inline (i.e. within browser where supported)
    $pdf->setTitle("Test PDF")->output('I', 'test.pdf');
} catch (\Exception $e) {
    // catch any errors in rendering the PDF
    if ($e->getCode() == 267) {
      die('The compression on this file is not supported.');
    }
    die('There was an error generating the PDF.');
}

exit;

$pdf = new PasswordProtectPDF("test.pdf", "mypassword");
// force the PDF to download to filename specified
$pdf->setTitle("Test PDF")->output('D', 'test.pdf');

exit;

$pdf = new PasswordProtectPDF("test.pdf", "mypassword");
// save PDF as file on the server
$pdf->setTitle("Test PDF")->output('F', 'test.pdf');

exit;

PasswordProtectPDF.php

<?php
require "vendor/autoload.php";

use setasign\Fpdi\Fpdi;
use setasign\Fpdi\PdfReader;
use setasign\FpdiProtection\FpdiProtection;

class PasswordProtectPDF
{
    protected $pdf = null;

    public function __construct($file, $user_pass, $master_pass = null)
    {
        $this->protect($file, $user_pass, $master_pass);
    }

    public function protect($file, $user_pass, $master_pass = null)
    {
        $pdf = new FpdiProtection();
      
        // set the source of the PDF to protect
        $pagecount = $pdf->setSourceFile($file);

        // copy all pages from the old unprotected pdf in the new one
        for ($i = 1; $i <= $pagecount; $i++) {
            // import each page from the original PDF
            $tplidx = $pdf->importPage($i);
          
            // get the size, orientation etc of each imported page
            $specs = $pdf->getTemplateSize($tplidx);
          
            // set the correct orientatil, width and height (allows for mixed page type PDFs)
            $pdf->addPage($specs['orientation'], [ $specs['width'], $specs['height'] ]);
            $pdf->useTemplate($tplidx);
        }

        // set user and master passwords, and allowed permissions
        // the master password allows the PDF to be unlocked for full access
        $pdf->SetProtection([ FpdiProtection::PERM_PRINT, FpdiProtection::PERM_DIGITAL_PRINT ], $user_pass, $master_pass);

        // set app name as creator
        $pdf->SetCreator("My Awesome App");

        $this->pdf = $pdf;

        return $this;
    }

    public function setTitle($title)
    {
        // set the title of the document
        $this->pdf->SetTitle($title);

        return $this;
    }

    public function output($name, $type = 'I')
    {
        // output the document
        if ($type === 'S') {
          return $this->pdf->Output($type, $name);
        } else {
          $this->pdf->Output($type, $name);
        }

        return $this;
    }

}