Can podofo support pdf to open LTV signatures?

[HANKO]

PDF LTV signatures, or long-term validation signatures, are digital signatures that are embedded in PDF documents and include a timestamp of the time of signing. This timestamp helps to validate the signature's authenticity, even if technological changes occur in the future.
Can podofo support pdf to open LTV signatures?

[Francesco Pretto]

The question is a bit vague since it does not really specify better what it is intended with "opening" LTV signatures, and I know it can be a complex subject. If the request was if PoDoFo supports validating a signature and ensure the certificates of the signer and the timestamp authority were valid at the moment of the signing that won't probably be implemented in PoDoFo as this is a very high level functionality. PoDoFo could implement some facilities to retrieve the necessary information to validate, though. For example it could:

• Return the raw bytes of the signed hash of the document;
• Recompute the raw bytes of the hash of the document that was signed;
• Return the certificate of the signer and other attributes of the CMS. Note that signing time today is most often already accessibile through PdfSignature::GetSignatureDate with modern signatures, and not inside the CMS structure;
• Return the raw bytes of the CMS block in the signature /Contents value for external processing;
• Return all the certificates supplied by the document for the LTV validation.

I leave this message here as possible ideas for the future, but can't promise anything of this list can be implemented anytime soon.