Q: We are planning a document download site and we want a simple
system that will lock a .pdf file onto the recipient's hard drive,
allow reading and printing (3 copies, then becoming a read only file)
but most importantly, will not permit copying or moving from that
hard drive without a further permission being sought. Can this be
implemented using PDFNet?
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A: You can use PDFNet SDK (www.pdftron.com/net) to work with standard
PDF security (please see EncTest sample project -
www.pdftron.com/net/samplecode.html#EncTest), to implement custom
security, or to create a custom DRM PDF viewer.
Unfortunately there is no 'standard' security mechanism in PDF that
will prevent users from saving or copying PDF documents. 'Standard
PDF' security offers basic permissions that can be easily overridden.
Also security schemes based on Acrobat plug-ins (etc.) can be easily
compromised.
An alternative is to implement a custom PDF viewer that would allow
reading of PDF documents encrypted with custom security (these PDFs
would not be readable in Acrobat or third party PDF viewers). A PDF
viewer from PDFNet SDK (see http://www.pdftron.com/net/samplecode.html#PDFView)
can be extended to support custom security permissions and behaviors
(such as time expiration, the number of times a document can be
printed, whether a document can be emailed/saved etc). You can also
use the same SDK to customize the viewing experience for your reading
audience (e.g. eBooks, CAD/CAM, interactive content, etc). The custom
viewer can be distributed as an integral part of eBook download,
through 'one-click' deployment, or as a traditional desktop
application. Using PDFNet SDK you can also create custom security
handlers to secure and process arbitrary PDF documents.
As an example of a recent PDF DRM application developed using PDFNet
SDK, you may want to take a look at Drumlin reader (http://
www.drumlinsecurity.co.uk/, http://www.drumlinsecurity.co.uk/PressLaunch.pdf).