Does anybody know of a PDF library that provides DRM functionality to cover offline expiry and sharing prevention? Needs to be PHP or Perl based.
I remember doing some research on this a year or so back. A lot of the DRM features provided in the PDF format are vendor specific extensions. The main DRM features are locked to the Adobe Acrobat Reader by a key/certificate embedded into the documents themselves. When I researched it, the only software capable of generating this key/certificate was Adobe's own. A quick look suggests this hasn't changed.
In summary, I don't think there's any software out there, besides Adobes (LiveCycle for example), which can unlock these features for you.