Is it possible either via .js or flash to silently be alerted when a .pdf is opened? Further is it possible to set (flash) cookies to enable tracking, again with no user notification?
I appreciate tracking only works with an internet connection, and a .pdf reader that supports script execution. This is not intended to be bulletproof.
I am not looking for a DRM solution, just a way to silently track if a .pdf is opened on more than 1 PC.