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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."
I don't completely understand what's going on here. And that's exactly my point. I don't want to understand. Does this breach disable any user's player until they update their hardware? Will some disks play and others not? (I'm kind of making this up, but I'm role-playing what most consumers are experiencing based on my limited anecdotal observations).
I don't want to know the ins and outs of the security of the media. I want it to work like the old CD players. I insert a disk, I watch a movie. Simple. Easy. Done.
I think above and beyond the hurdle of introducing a new format, ahem, two new formats, for DVDs this kind of hiccup could be fatal to the rollout. People are annoyed enough with little things (cables plugged in wrong way, audio/video receivers improperly configured, etc.), when it comes to having to update firmware to be able to play stuff they've paid for, they're going to be mad. And maybe some, maybe many are going to rethink their upgrade plans and find regular DVD okay enough. And maybe people who have been considering HD DVD will stay away in droves. Fingers crossed.
No one can deny how convenient this is for the customers. The companies love us.
Copyright infringement is "piracy" in the same way DRM is "consumer rape"
How many of you like to have your computers controlled by media corporations and Microsoft? Voting time is now. http://defectivebydesign.org/
And the update must have the new key in it!
And we know how smart InterVideo have been about protecting the keys so far...
The fact of the matter is that if it can be decrypted and the user has physical access, there is *no way* to make "unbreakable" DRM. None. At all.
Especially on most modern CPU architectures where memory and the bus are unencrypted. The data *has* to go through RAM and over the bus.
Therefore there *is no protection*
It takes *one* decrypt to defeat their supposed purpose "keeping them dirty pirates from getting it" and this decrypt will *always* happen. But yet they waste millions in R+D money making ridiculously bad systems to try to prevent something that's physically impossible to prevent.
It's a networked device. They'd just put out a firmware update. Sorry to shatter your dreams.
It would be more interesting to find out what would happen if the key to the Sony standalone BluRay players was discovered.
It should be a lot more difficult to get the keys for a hardware player than for a software player. WinDVD made an easy target because it is running on a general-purpose computer, which means that the key is sitting there in memory at some point to be snooped out. It's not easy, I'm sure, to find that key among the many megabytes of code, but it's there.
A hardware player isn't a general purpose computer. I'm sure it's possible for somebody with the right hardware to snoop inside its memory (say, inserting a special thingamabob between the memory and the mother board that allows you to read all reads/writes as they go past), but it's not going to be readily available.
Presumably somebody will be the first one to do this, and that is sure going to be a bad day for both formats. People are prepared to upgrade their software; it happens all the time and it's a relatively painless process for most people. Upgrading your hardware is not going to be easy, and it may not even be possible. (I used to own a DVD player which was "upgraded" by downloading a patch, burning it onto a CD, and putting that in the machine, but I don't know if every DVD player supports that.)
If they start denying keys on hardware players, there will be a world of pain, but I don't expect this to shatter the world. They'll just advise everybody to download a patch with a new key.
...and certainly not the last. Beware, HD-DVD/Blu-Ray consumers, you're in for a bumby road of software patches and exploits that move twice as fast!
"confirms that it's AACS key has been possibly revoked"
Well, I'm glad that's been confirmed...
If anyone really wants to piss off Sony, start a PS3 Linux project to build a PS3-based supercomputer that can be used to crack all of the Blu-Ray keys.
So when the key of your Samsung BD-P1000 is revoked, your player will no longer play any new disks that you buy. You will have to go out and buy a new player.
Of course, this is not the case; there are likely other ways of updating firmware on "real" HD-DVD players, but they're likely to be less transparent to consumers.
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Unfortunately, you're assuming that the memory holding the key is in a separate chip from the processor which will use it. These days, it's common for chips to have internal non-volatile storage (Flash). I bet (note: speculation) one of the design goals for AACS was to ensure that the key was never in-flight on a PCB trace. You can't probe a signal if it's routed internally in the silicon, never leaving the chip.
:(){
Having a network port is a mandatory feature for all HD DVD players, so updated keys and other updates can be easily delivered. It's mainly there for downloadable content (like adding subtitles in a new langauge for an existing disc).
Blu-ray, however, has networking optional, and most Blu-ray players don't have a port.
Yet another way in which the baseline functionality in HD DVD is much higher than Blu-ray.
My video compression blog
So when the key of your Samsung BD-P1000 is revoked, your player will no longer play any new disks that you buy. You will have to go out and buy a new player.
This entire thread is complete bullshit. Keys are not revoked via a network jack. Keys are revoked by the simple act of releasing new discs that don't support them.
So this bit is pretty well established
1. Player gets compromised (keys extracted somehow)
2. All new content no longer has a key for the compromised player.
a. Your player cannot play these new disks
b. The new content cannot be decrypted by hackers either.
c. Anything currently released will still play fine.
Now the interesting bit is how to update the players. The key system on Blu-Ray is very clever, and allows enough keys that they will never run out, at least in practice. It was designed to allow revocation of multiple compromised players, hundreds of times over.
The real issue is that you don't want a legitimate player to stop working. A software player can easily be updated on the internet. But a hardware player cannot assume an internet connection. And consumers are going to get angry if their player stops working because someone somewhere managed to figure out its keys.
However, there is no reason why a firmware update for the hardware player cannot be included on all new titles released. There is plenty of space on a Blu-Ray disk to hold thousands of firmware patches, for every compromised hardware player. So the end users will get updated.
Which doesn't mean that a real hacker couldn't "upgrade" their program too, but its a world of difference between figuring out a single key and emulating the system through an upgrade.
However, the biggest reason for this system is that of forcing a delay.
If you stop keys being released for a few months you capture most of the sales market
Sure, you may lose the long tail of marketing, but if you can just keep the decryption keys out of circulation for a few months plenty enough people will buy the disks anyway.
And they can play this cat and mouse game for a long time to come....
My 2c worth,
Michael
There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
None of that matters for hardware players, because each individual player can be revoked independently, without affecting the one that came off the line immediately before it, or the one that came right after it. They don't bother issuing unique keyset to each copy of a software player, for obvious reasons, but hardware players all have unique key sets so if the keys in one of them are compromised, and known to be compromised, then that specific player can be revoked so that future disks won't play on it. No updates to other players are required.
What makes this magic possible is a very clever and sophisticated key derivation scheme. Basically, there is an enormous tree of trees of possible keys, and each player is given a carefully-chosen subset of them, which allows that player to derive a large part of the possible keys, but not all of them. To revoke a key essentially just means choosing to encrypt future disks with a key that particular player cannot derive with keys.
The number of key blocks that must be placed on each disk to make this scheme work is linear in the number of revoked players. In fact, it can be shown mathematically that if r players have been revoked, then at most 2r+1 key blocks are required on each disk. Simulations show that assuming a random distribution of revocations, on average only 1.28r blocks are required. Each key block is 16 bytes in length, so they can revoke millions of players without significantly affecting the space available on the disk.
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Actually, it's very well-known what would happen: They would revoke the individual player that had its keys compromised. Note: Just that single unit, not the whole line. The beauty/horror (depending on your perspective) of the AACS key revocation system is that it can target individual units without affecting any other units, and it can do this without requiring huge amounts of disk space to be devoted to key blocks, and without requiring any of the devices to get updates, even if millions of individual players are revoked.
What this means is that smart hackers won't reveal the player keys they extract. Instead, they'll use those keys to compute the media keys, and then they'll publish the media keys. Your HD-DVD/Blu-Ray ripper will just have to consult an on-line database to find the key for the disk you have and then it will be able to decrypt it just fine. The media cartel won't be able to revoke the player key used to compute the media keys, because it won't know which ones they are.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.