Is there a way to read invalid digital signatures in a PDF file using VBA code?

Report · Jul 21, 2017

I'm trying to verify existence of digital signatures (validated or not) in a PDF file using VBA code. Thanks to thread 2214538, I have code to do that. I have two issues.

1) I have to wrapper the call to "jso.getField(f).SignatureInfo.Name" if the signature field is blank otherwise VBA throws error 438 - "...doesn't support property"

While I have a solution to this issue, I'm just curious to why this happens. I assume because there is no signature object?

2) I have a PDF file where I can visually see the digital signatures but my code reports the fields as blank. I do notice that they are not validated in Acrobat Pro (no blue bar across the top).

Is there a way to read invalid digital signatures in a PDF file using VBA code?

Report · Jul 23, 2017

1 – Correct. You really should be checking on the validuity of the results of getField() before you even bother trying to get its properties. (standard good programming technique)

2 – Then it’s NOT a Digital Signature. Instead it may just be a simple graphic of a signature.

Report · Jul 24, 2017

Well, I see the original signature of the person who sent the PDF for confirmation. In fact, she cannot send the PDF unless there is a valid signature. The person in the field who confirms the PDF (shipment) should be using Acrobat Pro 11 like we are, but there is no guarantee that they are. I'm not sure how they would even know how to create a graphic of a signature. They simply click in their signature field, digitally sign the PDF, save it, and send it back to us. Is there a way to programmatically check for the existence of a signature graphic (object)?

Report · Jul 24, 2017

Sounds like you need to find out more about the workflow and also investigate the internals of the PDFs you are receiving…