Copyright enforcement through crypto

[sdw@lig.net (Stephen D. Williams)]

I'd like to explore the technical problems of enforcing copyright 
restrictions through encryption and custom viewing software.

What I have in mind is a viewer, say a spin off of Mosaic, that has
a general purpose decryption engine that could be programmed with an
algorythm as part of the document download process.  The goal I have
in mind is to make possible one time, or limited time viewing of a
downloaded document  The document would be encrypted with the selected
method and keyed with a timestamp.  The client would need access to a
timeserver and a session key, etc. to decrypt as close as possible to
the display hardware.

This could be prototyped as a user process, but securely implemented
as an extension to X, MS-Windows, etc.

I haven't worked out all the problems, but see quite a few already.
Obviously, the goal would be to get really good copyright material on
the net, like first run movies, when we have the bandwidth.

Just wondering what minimum collection of hardware, software, and
infrastructure would be needed.  Of course, this is related to the
pay-per-use software paradigm (vs. current unlimited license).

sdw
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