At 12:30 AM 7/15/03 -0400, Don Davis wrote: >"An electrical engineer at Washington University > in St. Louis has devised a theory that sets the > limits for the amount of data that can be hidden > in a system and then provides guidelines for how > to store data and decode it. Contrarily, the > theory also provides guidelines for how an > adversary would disrupt the hidden information.
"But the theory answers the questions, what is the optimal attack.." There are ways of preventing any modification (attack) of the carrier. E.g., sign the carrier (with the private half of a widely published public key). Although this technique would attract attention until widespread. Note that Disney has to do this as well as Osama, lest someone post Disney content, with the "not ok to copy freely" watermark mutated. Otherwise a downloader would protest, "but the file said it was free, and the included-file-hash said it was intact!" (Because the mutator also provided a new hash.) (Disney's situation is worse, of course, because even the pristine, Disney-signed content is copyable at the analog (etc) level. And Osama can use multiple images as carriers for a single message.) --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]