Determine authenticity of PDF document based on metadata fields

Mark C
Mark C used Ask the Experts™
on
Hi,

I am trying to find information or definitions of metadata fields in PDF.
MetadataSpecifically I am trying to determine how the following field is created

http://ns.adobe.com/pdfx/1.3/            pdfx:SourceModified:D:20180806072738

Please see attached screenshot.  The highlighted orange areas match with the information in Document Properties.

The yellow fields are of interest.  Do these indicate (reliably) that modifications have been made and is the field for the Application used set in stone once the document is created?

I have tried some internet searches and I can t find anything to point me in the right direction.

The purpose is to determine if this document is genuinely from 2004 or recently modified

Many Thanks
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David FavorFractional CTO
Distinguished Expert 2018

Commented:
https://helpx.adobe.com/acrobat/using/validating-digital-signatures.html describes how to digitally sign a PDF.

This is the only way to be sure... or if you have a decryption key for an encrypted PDF.

PDF files are just text files so anyone can jam any meta data into an unsigned PDF, just like forging an email.
Mark CConsultant

Author

Commented:
Thanks David,

This helps for future reference.  The problem is trying to identify if when or how this file may have been modified and it doesn't have a digital signature.

I'm very interested in the fields that show in the metadata under ns.adobe.com

It appears to me that maybe these time stamps come from an interaction with the ns.adobe.com rather than from the PC that creates the doc. In doing some testing today I am able to manipulate the creation dates buy altering the date on my PC but this field still pickups up the correct date.  So it must be validating and timestamp against the URL.

Just haven't been able to find any info about what the field definitions are and how they are created
Consultant
Commented:
Never found the solution

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