Only last signature is valid when adding multiple signatures

[Capt KT]

We are using certificates/digitally sign to sign documents. Before signing, we add pages using organize pages and then optimize the file. The added pages are a pdf file with no signatures. Before adding the pages, the pdf can be signed multiple multiple places in the document and all signatures are valid. When adding signatures after adding the pdf pages from a file, only the last signature is valid. 

When PDF is first printed from Word, can add multiple signatures and all are valid.

When PDF is first printed from Word and additional pdf pages are added, only the first signature is valid when adding signature in multiple places. No changes to the pdf are made between adding each signature. First signature is added, move to second location and add next signature; the first signature changes to invalid.

Thanks.

[Amal.]

Hi there

Hope you are doing well and sorry for the trouble. As described after adding pages from a different PDF file to the document and doing multiple digital signature , it invalidates the previous signatures on the document.

Is this a behavior with a particular PDF file or with all the PDF  that you try to have multiple digital signatures? Please try with a different PDF file and check.

What is the version of the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version installed. Go to Help > Check for updates and reboot the computer once.

As you are using Digital signatures,  you have to place multiple signature fields on the document. And under the Field properties > Signed Tab, make sure you are not locking the document. Once the final signer signs the document He/She can choose to lock the document.

Hope this information will help

Regards

Amal

[Capt KT]

Hello,

We are using Acrobat Pro DC  (32-bit) Version 2021.005.20060.

The pages are added before any signature is added. So, pdf pages are added to the main pdf and then the combined document is signed. I completely understand that you cannot sign and then add pages as that will invalidate all signatures.

The validating Summary on the invalid signatures says "The document has been altered or corrupted since the Signature was applied.

Once the first signature is added, we move to the next signature location and sign. Nothing else is done between adding the two signatures. If I do these same steps to the original pdf without adding pages, all signatures stay valid. It is only when pdf pages are added (again, prior to adding signatures) that the problem occurs and only the last signature remains valid.

The pdf file that we were adding to the end of the original pdf is made up of about 7 other pdf files. Instead of adding the combined pdf, I added each individual file and signed. All of the files added worked correctly and the signatures stayed valid until the last one. Looking at the last file, I did not see anything that would cause an issue. Looking at the security tab under document properties, everything was allowed. So, I tried printing the suspect file to pdf and added it to the main document. This worked! So, I printed the  full file we were adding (7+ pdfs combined), and it worked. The signatures stayed valid. I still do not see anything in the one file that would cause the problem, but I was able to get around it. 

[MikelKlink]

Ok, so I apparently misunderstodd you in my other response.

Maybe you should share the files in question for analysis, both before and after signing.

[Bernd Alheit]

Printing to PDF invalides the signatures.

[MikelKlink]

Before adding the pages, the pdf can be signed multiple multiple places in the document and all signatures are valid. When adding signatures after adding the pdf pages from a file, only the last signature is valid. 

If I understand this correctly, you start with a PDF that already has multiple signatures, then you add some pages to it, and then you sign it again.

In that case already adding the pages breaks the old signatures: Only a few kinds of changes may be applied to a signed document without breaking the signatures, and adding pages is not among them.

For some backgrounds have a look at this stack overflow answer and the documents referenced from there.