PDFTron Validation fails once two or more signature are added

[eager.junkier-0l]

Product: PDFNetPython3
Product Version: 9.1.0

I’m currently working on a project that requires me to be able to add 2 or more signatures to a PDF file. However, once more than one signature is added, PDFTron signature verification would fail.

I asked the question on stack overflow. Ryan reached out to me and suggested me to discuss it here. I hope I can get a reply from support team soon. Thanks

[system]

Hello, I’m Ron, an automated tech support bot

While you wait for one of our customer support representatives to get back to you, please check out some of these documentation pages:

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• Adding a license key - Common questions
• Sign a PDF document in Python - About Adding An Approval Signature to a PDF Document
• Convert to PDF with virtual printer in Python - About converting to PDF
• Encrypting & securing PDFs in Python - About securing a document with encryption

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• How to Convert a Python Script to an Executable File (.exe) include PDFTron
• Creating PDFDoc with remote file
• How can I invoke PDFNet’s Direct Microsoft Office Conversion Add-on using Python?

[Ryan]

Thank you for reaching out. As discussed on Stackoverflow, Adobe is not strictly following the PDF standard when it comes to signature validation, which in the past has left it open to some attacks and spoofs.

This is why we have the e_compatibility_and_archiving option to allow some relaxation of validation, rather than the preferred/safer e_maximum option.

https://www.pdftron.com/api/PDFTronSDK/dotnet/pdftron.PDF.VerificationOptions.SignatureVerificationSecurityLevel.html

To assist you further it would be great to learn more about your requirements.

Especially with regards to Validation and if there are particular vendors you are targeting.

[eager.junkier-0l]

Dear @Ryan, thank you for reaching out to me. I’ve been very busy with the project lately. Basically, it requires me to add multiple digital signatures to a PDF file indicating multiple people has approved the document. I’m also using self-signed certificate for each signature. Can you tell me if there’s a way I can add multiple signatures without causing a verification failure? I really hope there is a solution to this issue.