You can check out
Wikipedia’s AACS entry if you want some more information on AACS. If I recall correctly, the way this works is that all computer drives that can read content (discs in this case) protected with AACS have to have some NVRAM in them. When a disc is inserted the drive–the actual hardware, mind you–scans a certain area of the disc to read a list of revoked player keys. Now, when the software player wants to talk to the disc drive, it has to identify itself with some encryption (and the drive also identifies itself back to the software, I think). So if you put a new disc in the drive, and that disc says your player’s key is revoked, that drive will never again speak to a software player that identifies itself with that revoked key. Pretty cool. (Assholes.)
