Q: Can we use PDFNet SDK to develop a custom DRM system for PDF?
We would like to develop a DRM that restricts the number of copies,
prints, ... limited time for viewing etc.
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A: You can use PDFNet or SilverDox to develop a custom viewer and DRM.
As a starting point you may want to take a look at the following
samples:
PDF Viewing:
PDFViewSimple: http://www.pdftron.com/pdfnet/samplecode.html#PDFViewSimple
PDFView: http://www.pdftron.com/pdfnet/samplecode.html#PDFView
PDF Encryption / Decryption (to be used by your command-line tool and
the viewer):
EncTest: http://www.pdftron.com/pdfnet/samplecode.html#EncTest
To develop a custom DRM you would build a custom security handler.
Another approach to build a custom security handler is described in
the following article:
http://groups.google.com/group/pdfnet-sdk/t/360aa59d09f77a28
In the article developer is using Java, however the same technique
works in C# and other supported languages.
For viewing documents online (i.e. in the browser) your developers may
also want to take a look at SilverDox (http://www.pdftron.com/
silverdox). SilverDox could be used for secure online document viewing
of your DRM protected documents on Windows and Mac without any
software installation beyond Silverlight. You can access some online
samples from the following page: http://www.pdftron.com/silverdox/samplecode.html