This is just a wrapper around pdf.js, so probably yes. But you should know that if it is viewable by pdf.js in the browser then it will be possible to download

This is just a wrapper around pdf.js, so probably yes. But you should know that if it is viewable by pdf.js in the browser then it will be possible to download it without a password too since you need pdf.js to somehow read the file and pdf.js runs client-side.