digitally sign the PDF document (waler)

rbuser

Hi!

Is it possible to digitally sign the created PDF document?
I have some customers with a 'digital certificate' and they use our
application to email invoices and other documents to theirs clients.
They want to digitally sign the PDF invoices they're sending, just to
'authenticate' them.

Is it possible or have they to buy a PDF third party plug-in?

Thanks in advance!