How does CSS scramble DVD contents?
According to the cryptographic analysis carried out by Frank Stevenson, CSS scrambles DVD contents by first using a series of keys (see question 3.1.2 ) to validate the authenticity of both the DVD and the DVD player, unlocking a title key which is then itself used as the main unscrambling key. Every DVD player on the market today is coded with a small set of “player keys” which identify that player as an authorized CSS playback mechanism; these keys are provided by the DVD licensing authorities (currently the DVD Copy Control Association) for a sizeable fee. There are currently just over four hundred player keys in circulation. Every DVD disc on the market today is coded with a “disk key”, identifying that disc. This key is not stored on the DVD in plaintext, but in encrypted form only. Each DVD contains a list of all valid player keys currently in circulation, encrypted against that DVD’s disk key. The disc also contains an plaintext hash value of the disk key. When a DVD player atte
