We reported previously that in January, a person using the alias muslix64 claimed to have circumvented the Advanced Access Content System (AACS) protection used in High-Definition DVD (HD DVD) and Blu-Ray DVD disk systems. Now another person claims to have found a master key that can unlock any disk protected with AACS.
You recall that AACS works by encrypting the digital content; encryption keys are then used to decrypt the data. The keys are embedded into the media players and the DVD media, and each DVD-based movie has its own unique key. Media players use their key to access the key stored on the media. Then the media key is used by the player to decrypt the digital content for playback.
Muslix64 was able to figure out how to derive the individual keys used for decrypting each DVD. Since muslix64's discovery, hundreds of movie keys have flowed onto the Internet.
Following up on what muslix64 discovered, another person who uses the name arnezami discovered a master processing key that can unlock all HD DVD and Blu-Ray disks, thus eliminating the need to discover individual movie keys.
Arnezami said that to find the master key, he slowed down the DVD video player and continuously scanned his computer for changes to a certain area of its memory. "Nothing was hacked, cracked or even reverse engineered--I only had to watch the \[changes\] in my own \[computer's\] memory. No debugger was used, no binaries changed," Arnezami said.
Although that master key can be revoked and replaced with a new key, some of those involved in testing Arnemazi's discovery method think that the method would work to find any replacement key unless AACS developers change the way the protection system works.
The AACS Licensing Administrator (AACS LA) was founded by IBM, Intel, Microsoft, Panasonic, Sony, Toshiba, The Walt Disney Company, and Warner Bros. Studios. No comment about the master key discovery was available from AACS LA at the time of this writing.