I have found this post in this forum talking about changes in Adobe Reader 9 about signature verification:
I have another scenario:
A PDF with two signatures.
After the first signature, a new page was added and then the PDF was signed again (using signature appearance).
Using Adobe Reader 8.1.5, the result of signature verification is successful for both signatures.
In fact, the byte range of the first signature is intact after adding the second signature.
But if I open it with Adobe Reader 9.2.0, the verification result is invalid signature (for the first signature): the document has been modified and there is a new page.
Since it seems that Adobe Reader 9 has added some new checks when verifying signatures,
does anybody know (or know where can it be found) the list of new signature verification requirements of Adobe Reader 9 ?
Or the list of changes allowed in Adobe Reader 9 that do not invalidate signatures ?
Maybe a list similar to the changes allowed in the three types of certified signatures (TransformParams)?
Thanks a lot in advance
The document I was searching for is in Adobe site and is called "Adobe Acrobat 9 Digital Signatures, Changes and Improvements".