First AACS Blu-Ray/HD-DVD Key Revoked

Thomas Charron writes "An update posted for Intervideo WinDVD 8 confirms that it's AACS key has been possibly revoked. WinDVD 8 is the software which had its device key compromised, allowing unfettered access to Blu-Ray and HD-DVD content, resulting in HD movies being made available via many torrent sites online. This is possibly the first known key revocation which has taken place, and little is known of the actual process used for key revocation. According to the release, 'Please be aware that failure to apply the update will result in AACS-protected HD DVD and BD playback being disabled,' which pretty much confirms that the key revocation has already taken place for all newly released Blu-Ray and HD-DVD discs."

Comments

Re:I don't completely get it.

[scottnews]

It means *NEW* HD-DVD and Bluray discs won't work on WinDVD 8. The key for WinDVD 8 has been revoked. Other players use different keys. Those have not been revoked. WinDVD has released a free update with a new key, and presumably an attempt to encrypt it.

This is why HD-DVD and Bluray players require a network jack. It allows for old keys to be removed and new ones to be implemented, among other things.

Re:I don't completely get it.

[Kjella]

What this means is that *NEW* HD-DVD and Bluray discs won't work on old players, unless patched.

Actually:
1. New discs won't play on the players who has had their keys revoked. Just to make that clear, this only has any effect for users of the WinDVD software player.
2. If I remember correctly, the player will keep a version of the revocation keys. So from what I've understood, once you put in a disc which says "Hey, you're supposed to be revoked" that player will stop working until you get an upgrade.

For a software player, this isn't more than what it just said - a required software update. It doesn't get nasty until hardware keys are found...

Re:I don't completely get it.

[SiliconEntity]

once you put in a disc which says "Hey, you're supposed to be revoked" that player will stop working until you get an upgrade. This myth appears to have originated...

It's not a myth at all. Try reading section 4.8 of the AACS Introduction and Common Cryptographic Elements spec:

An AACS licensed drive shall retain in non-volatile storage, the most recent Host Revocation List (HRL) data which it encounters and has verified. To do this, for the first AACS drive authentication to the media inserted, the drive shall read an MKB recorded on the media to check if its version is higher than the version of HRL that it has stored in its non-volatile memory... If the version of MKB recorded on the media is higher than the version of HRL that the drive has stored in its non volatile memory, the drive verifies the signature in the Host Revocation List Record of MKB as specified in section 3.2.5.2. If the signature is successfully verified, the drive shall replace the previously stored HRL data, if any, with the newly read HRL data.

What this means is that disks are distributed with Host Revocation Lists on them, cryptographically signed by AACS. Whenever a disk is inserted, the drive checks to see if the HRL on the disk is newer than the one it has in nonvolatile memory, and if so, it checks the AACS signature on the new one and stores it in memory. This allows a drive to refuse to talk to a given host software. Likewise there is a drive revocation list that the hosts are supposed to hold which tells them not to talk to certain drive versions, in case an attack is found in some models of drives.