I have a client who sells his e-book via a paypal interface.
The client is very concerned about the security of his e-book.
I have set him up an awesome file serving system that serves the file sercurely after paypal.. but now my client is asking if I can put some form of tracking system in the pdf.
So when someone downloads the pdf, I need to put something
(probabbly an md5 of the purchaser's email)
in the pdf, so that if a copy of the pdf does leak out to the public,
We can trace it to the purchaser.
How can i go about this without blowing up the file.
Ive looked into PDFlib.. and after some reading, they will put their watermark on my pdf unless I purchase a 2000$ key.....
FPDF also looked like it might do what i need, if i use the FPDI extension.
Has anyone here has any experience with these?
Is there a simpler way to acheive this, then trying to use this new class?