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Re: Copyright enforcement through crypto

In article <[email protected]>, Stephen D. Williams <[email protected]> wrote:
>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.

[Disclaimer: this is what I gather, from looking at a competitor's

A subset of what you want exists: the Internet Bookstore (I believe it's
 called) has a viewer/dongle combination for customers that they ship to
 customers for (I think) $30.  I have no idea whether they've sold any,
 but I'd bet not (given the low level of sales Bibliobytes has seen
 without requiring $30 up front).

Their design presumably puts the user's key in the dongle; each book
 shipped is encrypted with it, so the books are (I think) tied to the

However, AFAIK there's no time-binding invovled, and I'm skeptical as
 to how easy that would be: once you've displayed information once, it's

L. Todd Masco  | "A man would simply have to be as mad as a hatter, to try and
[email protected]  |  change the world with a plastic platter." - Todd Rundgren