pdf signature requires validation vs signature has problems

Question

Anybody, please explain what's the difference between signatures. When i open one PDF document - Adobe Acrobat 9 shows the message "At least one signature has problems" but if i open the other PDF then the message is "At least one signature requires validating". Seems like both PDFs were signed by self-signed certificates, but the messages are not the same. This difference is extremely significant for our business. Please help.

Answer 1

Making my comment an actual answer

At least one signature has problems implies that Adobe Acrobat has tried to verify the signature but failed doing so.

At least one signature requires validating implies that Adobe Acrobat has not tried to verify the signature and, therefore, has not yet decided whether it would fail or not.

Whether or not Adobe Reader / Acrobat tries to verify a signature depends on the Filter and SubFilter entries of the signature dictionary:

• If the Reader / Acrobat knows them, it automatically tries to verify the signature (unless the configuration settings were changed).

• If it knows the SubFilter but not the Filter, it does not try to verify automatically but at least offers to verify

• If it does not know the SubFilter, it does not try to verify.

The OP could verify this:

I've changed the subfilter from CMS to CADES and the message changed from "At least one signature has problems" to "At least one signature requires validating".

On any Acrobat XI, though, the message presumably will become "At least one signature has problems" again because Adobe meanwhile has started supporting PAdES subfilters.