# File lib/pdf/writer.rb, line 710
710:   def encrypt(user_pass = nil, owner_pass = nil, permissions = [])
711:     perms = ["11000000"].pack("B8")
712: 
713:     permissions.each do |perm|
714:       perms += ENCRYPT_OPTIONS[perm] if ENCRYPT_OPTIONS[perm]
715:     end
716: 
717:     @arc4 ||= PDF::ARC4.new
718:     owner_pass ||= user_pass
719: 
720:     options = {
721:       :owner_pass   => owner_pass,
722:       :user_pass    => user_pass,
723:       :permissions  => perms,
724:     }
725:     @encryption = PDF::Writer::Object::Encryption.new(self, options)
726:   end