Q: I encountered a PDF for which Acrobat 9 reports all permissions are
allowed. But PDFTron reports some permissions aren’t allowed, i.e.
Print. Acrobat 8 agrees with PDFTron however. I know Acrobat
sometimes breaks things, but sometimes they change because the older
version was reporting incorrect information. So I was wondering if
you can confirm the permissions reported by GetPermission() are
correct for this PDF?
A: PDFNet returns the same permissions that are listed in ISO PDF
specification (TABLE 22. - Section 188.8.131.52 'Standard Encryption
Dictionary'). When checking permissions you would need to take into
account the revision of the standard security handler as well as the
fact that some permissions override other permissions; e.g. bits
6,9,11 can override bit 4).
Please keep in mind that these bit flags (low-level permissions)
doesn't directly map to Acrobat user interface (which is subject to
change and was changing from one version to another). If you would
like to mimic Acrobat GUI, you would need to do find the right
combination of PDF permission bits (i.e. SecurityHandler::Permission-
s) that corresponds to specific high-level GUI elements.
If Acrobat 9 is reporting that the provided file can be printed, it
means that there is bug in their software.