Is it possible to remove a Password from a PDF file using PHP?

Question

I would like to ask if it\'s possible to use PHP in removing a password from a password-protected PDF file in which I already know the password? I\'ve seen this page which p

Answer 1

I use qpdf on linux to remove pdf password. To install run:

sudo apt install qpdf

Here is the function which invokes qpdf from php:

function removePdfPassword($inFilePath, $password, $outFilePath)
{
    if (empty($inFilePath) || empty($password) || !file_exists($inFilePath)) {
        return false;
    }

    $cmd = 'qpdf -password=' . escapeshellarg($password) . ' -decrypt ' . escapeshellarg($inFilePath) . ' ' . escapeshellarg($outFilePath);

    exec($cmd, $output, $retcode);
    $success = $retcode == 0;

    if (!$success) {
        @unlink($outFilePath);
    }

    return $success;
}

Answer 2

Of course it's possible, all you need to do is reverse engineer the encryption and compression and implement the reverse operations in PHP - but why bother:

<?php
   `gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=unencrypted.pdf -c .setpdfwrite -f encrypted.pdf`;
?>

C.