I am planning to send out a confidential document to a number of people. Each of them will have to sign a non-disclosure agreement. Yet, maybe the document will find its way to the internet. If I happen to come across the document, I want to be able to identify who's made it available on the internet so I can contact the person.
How would I embed some sort of invisible signature that I can verify on a published version? I don't want the user to go through the hoops of entering a password. I also don't want to embed a clearly identifiable name. I'd just create a spreadsheet with names and associated embedded signature for later identification purposes.
I understand nothing's foolproof and someone could just copy the contents, rewrite it or whatever. I just want to increase the hurdle by embedding some sort of "silent" code in the hopes the infringing party was careless enough to just make the document available as is.
I would prefer to use some simple LaTeX code, accessing something like
pdfinfo, rather than using a third-party tool.