How the mighty have fallen!
The encryption algorithms for Blu-Ray and HD-DVD content have been cracked!
The processing key is one of the keys used in the process of generating the media key, the unique key that encrypts the contents of a particular DVD. Due to the encryption algorithm used in Blu-Ray and HD-DVD technologies, they keys seem to work in a hierarchial manner: If you compromise a key lower in the hierarchy, you crack media. Compromise a key higher up in the hierarchy, and you crack all of the media encrypted underneath it.. meaning that all of the new generation DVDs may be freely decrypted, or at least up until they start pressing new-gen DVDs with a new processing key. Arnezami, the hacker who figured out how to crack AACS with this technique, refuses to state what software or hardware he compromised to get the processing key; given his description of the process (which does not, let me state, involve reverse engineering, only scanning memory contents) I surmise that he was working with a software player. Either that, or he's got one hell of a digital electronics lab at his disposal... by not tipping The Powers That Be off to what he compromised, this makes it harder for them to change things around and make it harder to find the keys again later.
The processing key he sussed out is this: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0