| IMHO, what would be FAR better would be for things that use the Xing keys | to go away, and something else used that exploited the weaknesses of the | CSS system itself. A couple of researchers have found that CSS is *SO | PATHETICALLY WEAK* that it takes merely a few seconds on a reasonably quick | computer to break the session key for the DVD without having *any* | knowledge of the compromised Xing key. That way the MPAA and CCA can't | claim that you are using a stolen key, because you are not using any of the | 512 player keys. You are simply figuring out what the session key is. Correct! CSS is so pathetic that breaking it in runtime is quite easily accomplished. Each DVD has a disk key, which is stored in a five byte hash on the disk. The disk key is also stored encrypted with all the various player keys. The layout looks something like this: 5 byte disk key hash Disk key encrypted with player key 1 Disk key encrypted with player key 2 ... Disk key encrypted with player key n When a disk is inserted, the player decrypts the disk key with its assigned player key, then hashes it and compares it to the 5 byte hash. Since CSS is a 40bit cipher (something to do with US export regulations I'm sure), attacking the keyspace is quite trivial to do (about a complexity of 2^25). Another interesting point is that with one player key compromised, one can derive the rest of the player keys through a similar search. -- Dan Moschuk ([EMAIL PROTECTED]) "Waste not fresh tears on old griefs." To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
