AACS LA Pulls the Trigger; Revocation System Under Way

By Scott M. Fulton, III, BetaNews

April 10, 2007, 7:41 PM

Last Friday, the Advanced Access Content System Licensing Administrator (AACS LA), which is responsible for providing the encrypted copy protection scheme for both HD DVD and Blu-ray high-definition disc players, exercised the option their system was designed to enable:

Through the distribution of new movie discs with embedded revoked keys, AACS LA will trigger a self-destruct system for PC-based high-def player software whose integrity from unauthorized copying is found to be compromised. And based on its last statement, the revocation could extend beyond Corel InterVideo, which warned its users last Friday.

Under the system which will get its first trials in the coming days, consumers will be prompted to upgrade their software in order to avoid the self-destruct sequence. The upgrade process will replace users' device-assigned decryption keys with new keys that would not be revoked, and whose identity has yet to be discovered.

But while multiple press sources over the past few days followed up on our story from last Friday by saying AACS LA announced it had fixed the problem, or patched the crack, that's not what the licensing authority actually announced. Rather, it said it had "taken action, in cooperation with relevant manufacturers, to expire the encryption keys associated with the specific implementations of AACS-enabled software."

What this means is that individuals -- including those who claim they're simply working to devise a way to back up their purchased discs, using a method that Congress could very well legalize this year -- may conceivably use exactly the same methods they used to detect the first set of critical AACS encryption keys, to detect the replacement set. Now that they know how, the detection process could actually be faster this time around.

As a result, the stage appears set for a kind of cryptographic volleyball between encoder developers and decoder programmers, with consumers finding themselves not feeling less like the passive observer and more like the ball.