You will notice that all Hyperlinks and bookmarks are clickable in these PDFs.
The page numbers on the tables of contents are clickable as well.

1. Example of Unencrypted PDF:

:: [Click here to view it.] ::

2. Example of Encrypted PDF with everything disabled:
(high quality printing, low quality printing, copy & paste, etc are all disabled)

:: [Click here to view it.] ::

3. Example of Encrypted PDF with password 123456 required for viewing:
(again, high quality printing, low quality printing, copy & paste, etc are all disabled)

:: [Click here to view it.] ::

You need a PDF reader to view PDFs on your computer.