title: Add a password to PDF files generated by Phantomjs
body: <p>I've got some server-side <code>node.js</code> code that generates PDF files on request, using <code>phantomJS</code>, and I'm looking for a way to add password protection to the output.</p>
  
  <p>Sadly I haven't found any mention of such an option in phantom, which makes sense because Chrome doesn't provide that either. Alternately I could run some other tool that would take the PDF created by phantom and add password protection to it, but I can't seem to find any that can do exactly that (add a password to an existing file) and that's completely free to use (preferably, non-GPL).</p>
  
  <p>Will be happy for suggestions on how to approach this task. Thanks!</p>