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Lord of War gets defeated by high-definition hackers
The hacker who cracked HD DVD strikes again by defeating Blu-ray Disc encryption

Late last year, a crafty individual who goes by the name “Muslix64” circumvented the copy protection scheme used to protect HD DVD. Given the similarities between the copy protection methods used in the high-definition optical formats, it was only a matter of time before Blu-ray Disc’s protections would be bypassed. However, Muslix64 has no access to Blu-ray hardware, limiting his exploit methods to HD DVD. That is, until Muslix64 came across some specific data for Blu-ray Disc, allowing him to apply his methods to the yet-uncracked format.

Another individual interested in Blu-ray’s protection scheme, “Janvitos,” who also participates in the same online forum where Muslix64 revealed his HD DVD work, posted a message showing the directory structure from a Lord of War Blu-ray Disc movie. Janvitos extracted the information by going through his system’s memory with WinHEX after playing the movie on his computer using WinDVD.

The memory dump information caught the attention of Muslix64, who replied to the thread saying, “In less [than] 24 hours, without any Blu-Ray equipment, but with the help of Janvitos, I managed to decrypt and play a Blu-Ray media file using my known-plaintext attack.” Muslix64 then posted a file as an example of his decryption work, though he did say that his method does not address BD+.

Muslix64 then went on to explain how he was able to accomplish this feat with his plaintext attack method. “This is a very basic, but [powerful] crypto attack that I have used to decrypt both [HD DVD and Blu-ray] formats,” he wrote. “After reading posts of people trying to get the keys in memory, I realized, I have a different way of looking into the problem…A lot of people try to attack the software, I'm attacking the data!”

“So I spent more time analysing the data, to look for patterns or something special to mount my known-plaintext attack,” Muslix64 explains. “Because I know the keys are unprotected in memory, I can skip all the [painful] process of code reversal.”

Although Muslix64 did not have any Blu-ray equipment at his disposal, he was still able to recover the keys with the help of Janvitos’ memory dump file and media file. Blu-ray media files are divided into individual aligned units. The first 16 bytes of each unit are not encrypted, with the rest being encrypted using AES in CBC mode. Muslix64 examined the non-encrypted portions of the data and found a reoccurring pattern, which he used to mount his known-plaintext attack.

Muslix64 goes on: “In most cases, the know-plaintext attack is in fact a guessed-plaintext attack. We ‘assume’ the data will look like something we ‘guessed’ when decrypted. Most of the time, it works! Knowing that, all you have to do, is to write a small program that scan a memory dump file, that comes from of a software player while it was playing the movie. The key is in that file, you have to locate it.”

Once the value and position of the key is in memory, all one has to do is to use a memory landmarking function to locate the key and defeat the encryption. The method discovered by Muslix64 and Janvitos is specific to Blu-ray, though similar means were used to decrypt HD DVD. This hack was made possible by the fact that the keys were not protected in memory when running video-playing software on the PC.

Even without any Blu-ray hardware at his disposal, Muslix64 shortly followed his findings reveal with the alpha release of BackupBluRay V.0.21, software he wrote to decrypt Blu-ray Discs. Limitations to his software at this time are that it doesn’t support BD+ or volume unique keys and that it only supports one CPS key per disc. Users wishing to utilize the software will also have to provide their own CPS unit key.

Those who have tried the software report that they have successfully been able to decrypt and copy their own Blu-ray Discs for playback on both PC software and set-top players. If the cracking of HD DVD and the release of pirated files is of any indication, however, Blu-ray may soon see illegal copies hitting the black market and parts of the Internet.



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RE: good job hollywood!
By randomname on 1/24/2007 6:12:31 AM , Rating: 1
Well, basically they haven't broken the AACS, but the software player. Given all the effort put into Vista, it is apparent the software players for XP will eventually be blacklisted. They may try to release new versions of the players for XP (that don't leave unencrypted software keys laying around in the memory) before revoking the old ones, but if even that doesn't work, all players for XP will be blacklisted. Maybe even all software players. For me it was surprising that they would allow software players for XP at all. I guess that was to get an early boost in the format war.

As for the performance drop in Vista due to polling the system, it will most likely be very small. The system is always running stuff in the background, and that is just one additional program/task. I found the article "A Cost Analysis of Windows Vista Content Protection" to be a poorly argumented, mostly FUD. The DRM will be inactive when protected content isn't run (apart from possible polling), but of course there will be a performance drop when protected content is playing. That performance drop is already manageable, and in a few years it will be a completely moot point.

Regardless of the OS (whether it is Vista, XP, OSX, or Linux), if you want legal playback of Blu-ray and HD-DVD, you must implement the DRM. Software players for systems that cannot implement the DRM will not be allowed. That is, if the industry as a whole doesn't change its mind, and view the approach as technically impossible / counterproductive. Somehow I doubt that will happen anytime soon.


"I f***ing cannot play Halo 2 multiplayer. I cannot do it." -- Bungie Technical Lead Chris Butcher

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