I've attempted to contact Adobe support about this issue, but they referred me here because the issue is with a previous version of Acrobat.
We use Acrobat Standard 11 to digitally sign documents using Adobe Certified Document Services (CDS) certificates issued by GlobalSign. Each document has multiple signatures, the first of which is the certifying signature, then the others are approval signatures. We've followed the Adobe guidelines for applying certificate based signatures (http://helpx.adobe.com/acrobat/using/certificate-based-signatures.html) and have not had a problem until recently when a client reported that the signatures are coming up invalid. When I asked which version of Acrobat they are using, he replied that they have Acrobat 9.
To test, I booted up a VM with Win7 and Acrobat Standard 9 (9.5.5) and was able to reproduce the issue. I opened the signed PDF in Acrobat 9, and the blue certification ribbon showed and indicated that all signatures are valid.
I opened the signatures panel and clicked the "Validate All" button and all of a sudden, the first (certifying) signature was now marked invalid.
The details of the invalid signature indicated that "there have been changes made to this document that invalidate the signature", but all I did was validate the signatures (they were checked and indicated as valid when the document was opened).
I know this is for an older version of Acrobat, but many of our clients are using version 9 and we'd like to be able to have the signatures appear valid (because they are). I've spoken with GlobalSign support who has verified that the certificate chain saved within the document is properly linked to the Adobe certifiate for CDS.
Any help is appreciated.
This could be a bug in Acrobat 9. I presume you have "Validate on Open" preference set, so that when you open a signed PDF all signtures are validated. What may happen is that on open the first (certification) signatures is validated but the second signature is not processed yet. When you revalidated all signatures, both signatures were already processed and the second validation detects some incompatibility. There were changes in Acrobat X and XI with respect to signature permissions which may not had been ported back to Acrobat 9.