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You might want to ask for a specific implementation on the product's forum.
I've worked with other pdf creators, and in those it's very easy to create a pdf with some test in it. Probably adding security should also be a simple option in the API. Otherwise you can always make it a password protected zip/rar, always difficult to crack.
Good luck!
You may be better off getting a licence for abdbe distiller to do this, or even looking at alternatives - like why not just stream the data to PDF & download it over SSL?