How to stop Acrobat from adding PDF metadata and invalidating PDF/1-b after digitally signing

[trevorp7928490]

We are having problems maintaining conformance to PDF/A-1b after digitally signing (for the second time) a PDF/A-1b file. It appears random that some users can do this and maintain conformance and others cannot. I have run adobe pre-flight to check what is wrong with the second signing, and get a message, "Syntax problem: Indirect object has object number no preceded by an EOL marker". However, we identified that there seems to be an intermediate by Acrobat that is causing the corruption.

This is a fairly complex situation, here are the steps and some details of the process we are doing to better explain the situation:

• We using Adobe Acrobat XI with PDF/A-1b files that have been digitally signed using certificates from a PKI.
• Source PDF files are stored in a read-only location and copied locally to a users machine.

Process:

1. The user copies a PDF/A-1b locally, opens it , and validates conformance to PDF/A-1b using preflight <-Validation SUCCEEDS
2. The user then applies a second digital signature using certificates from a PKI.
3. The user validates conformance to PDF/A1-b using pre-flight <- Validation FAILS

However, in other attempts using the same source file, the Validations SUCCEEDS.

I have ruled out data transfer corruption as the problem. Based on my examination of the HEX code of the PDF/A1-b (after it had been opened by Acrobat), and compared with the original read-only version, it appears that (sometimes) Acrobat appends metadata after the %%EOF in the file. It looks to be something related to the DocumentInfo properties. Then when the user tries to digitally sign the PDF/A-1b it invalidates because this metadata does not conform to PDF/A1-b. The odd part is that the user does not save the file.

My suspicions are it somehow relates to behaviours associated to the "Enable Editing" button or save. But our users do not click this button. Since you sign in PDF/A view mode.  Some users have changed their Preferences -> Documents -> View documents in PDF/A mode -> Never. We have seen the error in both sitatuins.

Any ideas what is happening, is there a setting that stops Acrobat from adding metadata on open?

thanks,