From: cactus@bb.com (L. Todd Masco)
Date: Mon, 19 Sep 94 16:34:44 PDT
To: cypherpunks@toad.com
Subject: Re: Copyright enforcement through crypto
In-Reply-To: <m0qmnoZ-0009tFC@sdwsys>
Message-ID: <35l7ej$670@bb.com>
MIME-Version: 1.0
Content-Type: text/plain


In article <m0qmnoZ-0009tFC@sdwsys>, Stephen D. Williams <sdw@lig.net> 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
 setup.]

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
 dongle.

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
 out.  

-- 
L. Todd Masco  | "A man would simply have to be as mad as a hatter, to try and
cactus@bb.com  |  change the world with a plastic platter." - Todd Rundgren