we have updated several times a signed (with timestamp) PDF to LTV using Adobe Acrobat DC just following these two steps:
* Right click on signature, click "Add verification info" (maybe in the english version its name could be slightly different)
* Then "Timestamp" the document
Up to now, it has always worked fine.
But we have found a problem with an specific PDF file.
It is PDF/A (but we haven't had problems with other PDF/A files) and it is signed with timestamp.
When opening it, Adobe says the signature is valid.
Then after clicking in Acrobat's "Add verification info" option, Acrobat itself changes the icon of the signature saying the signature has become invalid.
We have compared the two files (before and after adding verification info) and the updated file is identical to the initial file until the end of the initial file.
Then, the byte range of the first signature hasn't been modified when adding the verification info, so we don't understand why Adobe says the signature is invalid.
Could you please throw us light in order to understand why this signature becomes invalid after adding verification info ?
Thanks a lot in advance
PS: Since I don't know how to attach files, I have uploaded them here:
There are three files:
* before_adding_verification_info.pdf: The PDF with valid signature, before adding verification info.
* after_adding_revocation_info.pdf: The PDF with invalid signature, after adding verification info.
* democa.crt: The root certificate needed to validate signature