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Wim
Member
Member

PDF is digitally signed and cannot be processed further...

Hello,

How can we process digitally signed PDF's?

We just need to add a watermark and save it.

 

Regards,

Wim

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3 Replies
DavidU54339-XRX
FreeFlow Production Workflow Moderator
FreeFlow Production Workflow Moderator

Re: PDF is digitally signed and cannot be processed further...

When I submit a digitally signed PDF to my FFCore 6.2.0 system, I am not having any problems processing a watermark/save WF. Do you get an error message? Are you sure the PDF is not password protected?

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Wim
Member
Member

Re: PDF is digitally signed and cannot be processed further...

Just tested a simple save in FFCore 6.2.0 and still the same error.

The PDF is not password protected.

This is the message in 'Last Attempted Preset': 'Demographics: System Provided.'

The message in Status Details: 'PDF is digitally signed and cannot be processed further'

I found this in the MantisDebug.log: 

12-May-2022 08:40:59,467 [00000000-0000-0000-0000-000000000000][539 ]: [INFO ] DemographicsWorker com.xerox.solutionsdk.Worker.DoWork - Demographics: not writing trim-info-box for job 17155. Attrs: pdf-metadata,first-media-size,media-sizes,first-box-sizes,minimum-bleed-distance, Status: PDF is digitally signed and cannot be processed further.

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rstrating
FreeFlow User

Re: PDF is digitally signed and cannot be processed further...

I've escalated this issue because FFcore 6.0 can process this kind of PDF files and 6.2 not. This was the answer,

Unfortunately this is working as designed.

The whole point to digitally signing a document is so that you can guarantee it has not been modified since the last signature (ie it is identical to the signed version).

The Devs have had this question before and the response was:

 

“…Digitally signed PDF docs should not be modified otherwise it invalidates its authenticity. In the case of 2 up and 3up, for example, the document is being modified from it's originally signed content.”

 

As an FYI a digital signature is in essence a checksum for all the bytes in a PDF (not just a visible signature gif) which is stored internally in the PDF structure. One way you can edit a signed PDF in Acrobat is to “Print to PDF” which then creates a new PDF which does not contain the signature meta data. This then can be modified, but as you can imagine this would be difficult to do programmatically in an application like FFCore.

 

There are threads on the Adobe communities boards about editing signed PDFs, but they all really end with the comment that you shouldn’t, here are a couple of examples:

https://community.adobe.com/t5/acrobat-discussions/editing-a-signed-pdf/m-p/8794866

https://community.adobe.com/t5/acrobat-discussions/digital-signatures-and-combining-pdfs-in-acrobat-...

 

So to sum up, FFCore will not modify digitally signed PDFs, as the digital signature indicates that the document should not be modified.

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