I've been trying to encrypt a PDF document so that people wouldn't be able to copy text from it or print it. So, basically, I disabled printing and copying. I used this command:
qpdf input.pdf drm.pdf --encrypt "" pass 128 --print=none --modify=none --extract=n --
If I open it in Adobe Reader, it doesn't allow any copying, however if I use Evince, the text is easily copied. Does anybody have any ideas why?