On 9/25/25 01:59, Leonard Rosenthol wrote: > Please feel free to reach out to me directly with any issues about Acrobat.
Sorry, Leonard, but after further inspection, I think the issue is trickier than I first thought (and probably a corner case). https://gitlab.freedesktop.org/poppler/poppler/-/issues/1192 reports that a valid signature in “Acrobat” was giving errors in `poppler` (signed document attached). I first suspected the signer certificate was corrupted, but I was wrong (so the document may be malformed). In short, “Acrobat” cannot handle OCSP from signing certificate (and cannot determine its validity [also not even saying is expired in 06/27/2023]) and `poppler` reports "Signature Validation: Signature is Invalid." (also MuPDF unknown errors with both certificate and digest). I guess the tool that signed the document has embedded the signing certificate in a non-standard (or simply wrong) way, and probably this is giving different errors in different programs. I guess vast majority of people don’t really know what OCSP is. Sorry for the noise and many thanks for your help, Pablo
testing_signature_izenpe.pdf
Description: Adobe PDF document
