Slashdot Mirror


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."

49 of 254 comments (clear)

  1. I don't completely get it. by yagu · · Score: 5, Interesting

    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.

    1. Re:I don't completely get it. by Gossi · · Score: 3, Insightful
      What this means is that *NEW* HD-DVD and Bluray discs won't work on old players, unless patched. It's a consumer nightmare as they won't know nor care about HD-DVD piracy -- they just want a disc which works.



      Put simply: industry + clueless = idiots who damage their own profits. The music industry has proven this well already -- now it's time for the movie industry to not learn from the past.

    2. Re:I don't completely get it. by scottnews · · Score: 5, Informative

      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.

    3. Re:I don't completely get it. by Kjella · · Score: 4, Informative

      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...

      --
      Live today, because you never know what tomorrow brings
    4. Re:I don't completely get it. by LarsG · · Score: 2, Insightful

      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.

      Ouch. Imagine all the damage an enterprising anti-DRM vigilante can do if revocation lists can be faked. Or a SNAFU in the manufacturing plant.

      --
      If J.K.R wrote Windows: Puteulanus fenestra mortalis!
    5. Re:I don't completely get it. by SiliconEntity · · Score: 5, Informative
      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.
    6. Re:I don't completely get it. by whyde · · Score: 3, Interesting

      When I first became aware of AACS, I read what I could of the spec and pondered whether it would be possible to produce and distribute a disc which deliberately uses the properties of NVM and the MKB/HRL specification to insert a bogus "maximum value" HRL which contains a do-nothing (or nothing useful) revocation list.

      The net result of this is, once inserted, the disc guarantees that all future discs will play regardless of the player codes which have ever been, or will ever be, revoked. Since it has no concept of time except for the supposedly monotonically increasing version numbers of the HRL, it should be possible to max out the HRL value so no disc can ever update the player's revocation list.

      I'd be suprised to find out that this is not possible.

    7. Re:I don't completely get it. by Erpo · · Score: 2, Informative

      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


      It isn't a myth, but Host Revocation and Drive Revocation are trivial to bypass and are not what is being described in this article.

      HRLs and DRLs only serve to stop Hosts (PCs) and drives (HD-DVD or Blu-Ray) from communicating with eachother. For example, if a host's certificate is revoked and the drive knows this, the drive will not read certain bits off of the data medium and pass them along the ATA bus back to the PC. The bits are still on the medium and they are not encrypted or anything like that. The drive will just refuse to read them. This has already been fixed in at least one instance by flashing the drive's firmware. In any case, all one would need to do to get around this for good would be to make an HD-DVD or Blu-Ray drive that just reads the bits off of the medium and passes them back to the host PC just like a CD-ROM or DVD-ROM drive does.

      What's being described in this article is that the software player's "device keys" are being revoked. Here is how that works (basically):

      Each disc contains video that is encrypted with a master key. Each player contains a set of "device keys". The subset difference tree algorithm (part of the AACS spec) is used to encrypt the master key so that it can only be decrypted by a certain set of device keys. Before WinDVD 8 was revoked, the subset difference tree algorithm was used to encrypt the master key for each disc so that it could be decrypted by any set of device keys. Now, according to the article (or at least the summary), new discs are being produced for which any set of device keys can be used to recover the master key except WinDVD 8's device keys.

      So, if you managed to get a copy of WinDVD 8's device keys before today, you were set. You could decrypt, play, and copy any Blu-Ray or HDDVD disc. Now, you can't decrypt, play, or copy new Blu-Ray or HDDVD discs, at least until you get your hands on a new set of device keys...

      Note: I have deliberately dumbed down my explanation of the spec for two reasons. First, there are several intermediate keys that are involved in the process. Explaining the function of each and every intermediate key between the device keys and the title key would take a long time and not contribute any real information about the "spirit" of how AACS works. Second, the AACS spec is not fully implemented. According to what I have read, the AACS spec includes the concept of sequence keys that can be used for "forensic" purposes. However, the Sequence Key Blocks required to get any benefit from that part of the spec are not present on current Blu-Ray and HDDVD media.
    8. Re:I don't completely get it. by smchris · · Score: 2, Interesting

      Count me confused too. So what will be _really_ cool (anarchy-wise) will be when people release hacks for consumer media hardware of the future the way people hack game consoles to play linux? How do they tell what hardware has been conpromised? Each Blu-Ray disk comes with an explicit agreement to let the industry probe your hardware?

    9. Re:I don't completely get it. by Skreems · · Score: 3, Informative

      It's not. Or more specifically, not in the way you want.

      Storing the revocation list like this is likely only useful so that the device can give the user specific instructions to go look for an update, and maybe disable itself even for older discs. Every new disc will still fail to provide a disc key to the player, as the player key will not be included in the tree of allowed ones. You still couldn't play new discs, the best you might do is prevent the player from understanding that it needs an upgrade.

      --
      Slashdot needs a "-1, Wrong" moderation option.
      The Urban Hippie
    10. Re:I don't completely get it. by brandond1976 · · Score: 2, Informative

      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.
      HD-DVD is the only one that requires the player have the necessary hardware to access the network. In Bluray it is optional.
  2. Awesome by Vexorian · · Score: 4, Funny

    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"
  3. let's have a vote by Anonymous Coward · · Score: 3, Informative

    How many of you like to have your computers controlled by media corporations and Microsoft? Voting time is now. http://defectivebydesign.org/

    1. Re:let's have a vote by RightSaidFred99 · · Score: 3, Insightful

      You know, it's the damnedest thing. My computer is controlled by me. Everytime I see people whining about DRM I wonder what the fuss is. I run Windows XP and have had no issues with DRM because I don't buy DRM'd media. Instead of whining, I just put my money where my mouth is and so far I haven't fallen asleep cursing Microsoft or anyone else because I don't have any DRM issues to speak of. It's God Damned amazing.

  4. soo.... by Anonymous Coward · · Score: 2, Insightful

    so if WinDVD 8's AACS key gets banned, basically all WinDVD 8 has to do is issue a patch to give it a new key, so that future discs will work? seems like that would be something that would be hackable and exploitable... especially if other aacs keys are known, i imagine hacks would come out to change the program's aacs key to any known unblocked aacs key...

    it's entirely possible that i have this all wrong.

    1. Re:soo.... by Dachannien · · Score: 2, Insightful

      Knowing the key in the first place is the exploit.

  5. .. but what if a hardware player is compromised? by uncleFester · · Score: 2, Interesting

    this is what's more curious to me.. when/if a hardware player ever is compromised, what are you gonna do then? the content owner denies your access to their content.. you think the manufacturer will step up with an "oops, our bad; here's a new unit to play stuff.." har.

    i don't even know if this has happened with dvd or how possible it is.. but i have to think the potential is out there, and unless the unit has some sort of design foresight to resolve some issue (firmware updates to my bluRay player? and what kinda new 'security' hole is that?!?) i'd think you could be toast. .. that might actually be one class-action suit i could hop on and enjoy, just to watch potential legal fallout. :)

    -r

    --
    -'fester
  6. Copyedit? by interiot · · Score: 3, Insightful
    Can't Slashdot do a minimal amount of copyediting to stories before posting them?

    An update posted for Intervideo WinDVD 8 confirms that it's AACS key has been possibly revoked. WinDVD 8 is the software which had it's device key compromised,
    "Possibly" "confirmed" appears on its face as a likely contradiction, and it is... the linked article says "please be aware that failure to apply the update will result in AACS-protected HD DVD and BD playback being disabled".
    1. Re:Copyedit? by Anonymous Coward · · Score: 5, Insightful

      ... and for G*d's sake, it's "its," not "it's"!

      (World's easiest job: slashdot "editor.")

  7. hardware players? by MoOsEb0y · · Score: 2, Interesting

    What are the implications for hardware players? Will they now need to be updated, or does this key revocation only apply for WinDVD in particular. If so, does this mean that it would be possible to hack apart a hardware HDDVD/Bluray player and take its key? This doesn't seem like a very secure system if that kind of attack is possible.

  8. Great! by Bri3D · · Score: 5, Insightful

    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.

    1. Re:Great! by Nasarius · · Score: 4, Interesting

      And the clever cracking groups will grab a key and not tell anyone, just keep using it to make releases. It'll be amusing to watch and see what happens, though. Will they keep playing whack-a-mole when they can find which key has been extracted? Will they finally realize it's just not worth the effort? Or will they end up revoking all software player keys and forcing you to buy and use the hardware players? I'm betting on the latter.

      --
      LOAD "SIG",8,1
    2. Re:Great! by Bri3D · · Score: 2, Insightful

      Wrong. Why?

      The user still has to be able to *view* the content. There is no DRM for the mind (yet, hopefully ever).
      No matter how much fancy full-pipeline encrypted hardware you build, the user still has to see it. And our minds don't support AES.

  9. Re:PS3 by ivan256 · · Score: 4, Insightful

    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.

  10. It's hard to upgrade hardware by jfengel · · Score: 4, Insightful

    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.

    1. Re:It's hard to upgrade hardware by evilviper · · Score: 2, Informative

      The problem with that is then on every disc each key needs to be encoded.

      No, it doesn't. Mathematics isn't nearly that primitive. You absolutely don't have to, nor does AACS store every individual key on a disk. It's called "broadcast encryption" and it existed before AACS. Each player doesn't have a single, globally unique key. It has several keys which, in combination, are globally unique. See: http://web.archive.org/web/20060604054302/http://w ww.lotspiech.com/AACS/

      Sorry, it just won't work.

      Sorry, you know nothing about cryptography. That is, in fact, how AACS works. Your ignorance of it doesn't change reality.
      --
      Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
    2. Re:It's hard to upgrade hardware by evilviper · · Score: 3, Interesting

      A hardware player isn't a general purpose computer.

      Actually, it is. Toshiba's first HD-DVD players are, in fact, Pentium 4 computers.

      (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.)

      Not ALL, but the vast majority of DVD players can be flashed in the same manner.
      --
      Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
    3. Re:It's hard to upgrade hardware by IamTheRealMike · · Score: 2, Interesting

      AACS contains traitor-tracing algorithms that allow you to locate the device key from a decrypted video, or released title key.

  11. First AACS Blu-Ray/HD-DVD Key Revoked by denmarkw00t · · Score: 4, Insightful

    ...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!

  12. Re:Awesome Monopoly Powers, Activate! by Migraineman · · Score: 2, Insightful

    Thank you for using the word "customers" instead of "consumers." Consumers are force-fed; customers have a choice.

    But therein lies the problem with this situation. The **AA cartels have purchased the necessary legislation to reinforce their monopolies. When they revoke a DRM key that effectively bricks your hardware player for future media releases, what are you going to do? They've cost-shifted the upgrade burden onto you, and since they own the entire distribution chain, you can't take your business elsewhere. I'm quite surprised that the media cartels haven't tried to mandate use of Scrip to purchase a lease for their items-that-shall-not-be-owned-by-the-customer. Long live the Company Store!

    This is a perfect example of why monopolies are bad. This will resonate all the way down to Joe Sixpack in a form that he'll understand - "Damned 'new' movies don't play in my DVD player." He may not understand the ins and outs of DRM legislation, but he sure as hell knows what getting screwed by the establishment means.

  13. Ahh, certainty by Moridineas · · Score: 5, Funny

    "confirms that it's AACS key has been possibly revoked"

    Well, I'm glad that's been confirmed...

  14. New use for PS3 Linux by supabeast! · · Score: 5, Funny

    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.

  15. Re:Network jack?? by badfish99 · · Score: 3, Informative

    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.

  16. Re:Network jack?? by Dogtanian · · Score: 3, Informative

    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. Well, yes; I believe that was the point. WinDVD is able to be updated over the Internet, but this option isn't available for the Samsung DVD player (etc). If that were the only way of updating the firmware, then the industry would be faced with a choice of revoking the keys (i.e. having future releases no longer support that player) or not revoking them, thus leaving the crack open for exploit.

    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.
    --
    "Slashdot - News and Chat Sites Deviant". (Click "homepage" link above for details).
  17. thingamabob = logic analyzer by DeadCatX2 · · Score: 3, Interesting

    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.

    --
    :(){ :|:& };:
    1. Re:thingamabob = logic analyzer by Cassini2 · · Score: 3, Interesting

      You can't probe a signal if it's routed internally in the silicon, never leaving the chip.
      Keeping a signal "locked" in the silicon is more difficult than one would like to think. Most of the chips with built in non-volatile memory have built-in interfaces to program that memory. These interfaces can be abused, and people have done it. Microchip's secure chips were breached. I am not sure where the hackers are at with the latest 32-bit and 64-bit hardware. It is hard to make something that "no one can copy". It is really hard when no physical security is present. People can remove the chips from the players and expose them to out-of-spec signals and voltage levels to find out what happens next.
  18. Re:Network jack?? by JWW · · Score: 2, Insightful

    Oh, thats #$%#$% great, I can just see it now.

    Instructions for continuing to be able to use your (friken expensive) player.

    1) Use your computer to download the latest firmware.
    2) Burn a CD/DVD (you sure as hell had better not need to burn a blu-ray or hd dvd disk!!)
    3) Insert in you player and power cycle and hope the upgrade works and doesn't leave you with a brick.
    4) Continue to pay a premium for content for your player knowing that you'll probably have to do this firmware shuffle at least twice a year.

    or

    Don't by a blu-ray or hd dvd player ... ever. Honestly, I really don't want one of these things at all. With the cracking of CSS I have total rights to use the content I own on DVD. I won't quickly give that up for a few more lines of resolution and their draconian changable key system. Screw em'.

    I think the recording industry is going to be shocked, SHOCKED! at how well DRM free music it going to do on iTunes. Its the beginning of the end for DRM...

  19. right of first sale? by mrcubehead · · Score: 2, Interesting

    I was wondering, what if you bought a commercial disk and made a copy without protection (via copy circumvention in a country where fair use isn't demolished by the dmca, like in sweden), and then destroyed the original, and resold it as a "drm-free" version? No one can argue the content has changed... so doesn't this then fall under the right of first sale, which was upheld by the supreme court some time ago?

    1. Re:right of first sale? by ThePhilips · · Score: 2, Informative

      Since you are selling not original - but copy - no way it would classify as "first sale". IOW, private copies are reserved for private use - sale/rent/etc aren't private uses.

      P.S. IANAL

      --
      All hope abandon ye who enter here.
  20. All HD DVD players have a network port by benwaggoner · · Score: 3, Informative

    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.

    1. Re:All HD DVD players have a network port by DDLKermit007 · · Score: 2, Insightful

      Right, you honestly think a studio will give you ned content for your movie like subtitles that they didn't have yet? They have your money, and they won't do one extra thing thats not physically encoded on the disk unless it's to lock you our, or make more money (count on commercials getting delivered this way).

    2. Re:All HD DVD players have a network port by theJML · · Score: 2, Insightful

      So why is requiring me to run a network cable to my DVD Player a bonus? Can't I play a movie without having to worry about the current state of my network connection? Does my player really have to ask someone outside the house if it's ok to show me a movie? And honestly, I'll have to say when the network goes down, that's a perfect time to watch a movie... 'cause ya sure can't read slashdot. I remember the days when you all you needed was one utility company involved in movie viewing (power). What about all the people who are video/audiophiles who aren't net nerds? I think I'll stick with the Progressive Scan DVD hooked to my 32" HD Screen thank you.

      --
      -=JML=-
  21. Re:Network jack?? by Anonymous Coward · · Score: 2, Interesting

    Yep, just a few more lines. The original poster was correct. It's not a big deal like VHS->DVD was (random access, media doesn't degrade with repeated viewings, far better sound, menus and special features, no rewinding...). If you don't have a big screen TV, HD is absolutely worthless. My 27" TV is just fine with regular DVD and I don't need a theatre-sized screen in my living room.

  22. Re:Network jack?? by Oktober+Sunset · · Score: 2, Insightful

    Buh? I think the gp was alluding to the fact that no one except a few uber geeks have bluray or hddvd burners on their computers, and thus no one but aforementioned uber geeks would be able to burn a bluray or hddvd, and thus would be royaly fucked.

  23. If only people would wake up by Toby_Tyke · · Score: 2, Funny

    This is a perfect example of why monopolies are bad. This will resonate all the way down to Joe Sixpack in a form that he'll understand - "Damned 'new' movies don't play in my DVD player." He may not understand the ins and outs of DRM legislation, but he sure as hell knows what getting screwed by the establishment means.

    And the establishment will respond thus:

    Yeah, that copy protection sure is painful, huh? Goddamn those freedom hating movie pirates for making us put it on there. You know those guys fund terrorists? It's true. The 911 hijackers paid for their flight training with funds made hawking pirate copies of the Phantom Menace. You want to help fight terrorists, don't you Joe? So you don't mind this anti-piracy/anti-terror stuff, do you? Great. Here's a flag. Go back to sleep. [/channeling inner hicks]

    --
    "I realise this is not a very popular opinion but it's the truth, and there for needs to be said" -Bill Hicks
  24. Re:Network jack?? by mgv · · Score: 3, Interesting

    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.
  25. Updates for hardware players unnecessary by swillden · · Score: 3, Informative

    Well, yes; I believe that was the point. WinDVD is able to be updated over the Internet, but this option isn't available for the Samsung DVD player (etc). If that were the only way of updating the firmware, then the industry would be faced with a choice of revoking the keys (i.e. having future releases no longer support that player) or not revoking them, thus leaving the crack open for exploit.

    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.

    --
    Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
  26. Re:PS3 by swillden · · Score: 3, Interesting

    It would be more interesting to find out what would happen if the key to the Sony standalone BluRay players was discovered.

    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.
  27. Re:Network jack?? by Skreems · · Score: 2, Insightful

    Uh huh. I'm saying I have a 32" LCD HD television, and normal DVD resolution is just fine for me. Yeah, if you pause it and try to count freckles on some guy in the background, HD-DVD is gonna work a lot better, but when you're watching a film from 10-15 feet back and people are moving around on screen, it really doesn't make a difference. The average consumer does not care. Don't get me wrong, HD sets have some advantages. For one, you can use progressive scan to get a brighter image and drop that annoying flicker along line edges. That's a huge improvement. But paying extra for extra resolution that you're not really going to notice, and the privilege of working with a broken protection scheme? Nuh huh.

    Here's a couple neat facts for you: 1) many sets currently on the market have a broken implementation of HDMI that causes the authentication to fail. 2) There are literally NO computers which can currently play HD media in full quality. 3) No movies or TV shows are shot in 1080. Many are not shot in 720. The image that you get on an "HD" disc is most likely upscaled during the mastering process, to some degree.

    --
    Slashdot needs a "-1, Wrong" moderation option.
    The Urban Hippie