Hello Craig,

From what has been said till now, it is almost certain that introducing any kind of protection mechanism is going to be,

1. Not very effective as thieves are "more" smarter.
2. It will frustrate the genuine individual who wants to use it as a normal pdf document.

So having got a noble idea, why not see its logical conclusion? Forget who will copy and who will claim credit - your intentions are good and fair. Just do it and ignore the theft.

At least you know you have done a good deed and are not going to loose anything when a hacker copies it. Maybe the first few instances, the adrenalin will pump up - but I am sure with a little introspection it will soon become a non-issue.

Good luck

Raghu