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