Salvo,

Salvo Rapisarda wrote:
> [...] A postback of page is made with Javascript and the output of
> signature was encapsuled with iTextSharp inside the PDF at server-side.
> All it's done without problem, but when I open signed version of PDF with
> Acrobat Reader the sign is not valid with reason: the document was
> modified after the signing.
> 
> So the question is: I have made some mistake in my code or it's not
> possible to do a "asynchronous" signature process?

In principle it is possible, but you have to take care.

On the one hand, you must be sure --- as Andreas already mentioned --- to
calculate the hash for the range stream returned by
PdfSignatureAppearance.getRangeStream(), not simply the whole PDF file.

On the other hand, you should be aware that when you start creating a
signature at different times, the range streams will be different, even if
you use the same explicite input data. You have to inject the returned
signature container in the very PdfStamper instance whose
PdfSignatureAppearance's RangeStream you used.

Regards,   Michael.
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