Digital signature disappearing

[heloise_3765]

Hello,

I used the Adobe certificate feature to sign a professional document, but when I merge several documents using another tool, the signatures disappear. When I open the new merged document in Adobe and click on the signatures that are still there, I get the following message:

"Signature authentication error.

The signature contains incorrect, unrecognized, damaged, or suspicious data.
Support information: SigDict/Contents illegal data."

What can I do?
Thank you in advance for your help!
Heloise

[Randy Hagan]

When you create a signed PDF document, you're creating a new, secured version of the original PDF file before it was signed. In fact, you confirm this when you have to save the file after signing it, and it creates a second file.

When you combine several of those previously signed, secured files, you're again creating a new file. The file data signature doesn't make the trip, and the error message you're getting confirms that this new PDF file is not the signed PDF(s) that were originally secured by the digital signature. This is a feature, not a bug, because your combined file wasn't signed by anyone.

Hope this helps,

Randy

[heloise_3765]

Very helpfull, txs!!

[MikelKlink]

What can I do?

As Randy has already explained, you cannot combine the contents of multiple signed PDFs in a single PDF and hope for the signatures to remain valid. 

Thus, your options are to

• either combine those PDFs in a portfolio PDF; you mention you use a different tool for combining, so I cannot tell whether that tool is able to create portfolio PDFs; signed PDFs added to a portfolio PDF remain as well-signed as they were before;
• or flatten the signed PDFs before combining; this throws away the digital signature but keeps the signature visualizations. 

[heloise_3765]

Thank you so much for your answer! How can I flatten the signed PDFs before combining them directly on one single doc. Should I compress them. Txs in advance for your help 🙂

[MikelKlink]

For manual flattening printing the PDF to PDF seems to be the most often used approach.