// January 13th, 2007 // 8 Comments » // Hacks, tech
So many people in the security world have been talking for the past few weeks about cracking HD DVD. Steve Gibson from Twit’s Security Now podcast was also talking about it last week. So I read about HD DVD and it’s Advanced Access Content System (AACS), and here’s what I got.
HD DVDs use a digital rights protection method called AACS. The group developing it includes Disney, Intel, Microsoft, Matsushita (Panasonic), Warner Brothers, IBM, Toshiba, and Sony. HD DVDs simply use AACS to protect their contents from being copied, so that you’ll only but original HD DVDs.
AACS-protected content is encrypted under one or more title keys using the Advanced Encryption Standard (AES). Title keys are derived from a combination of a media key and several elements, including the volume ID of the media (e.g., a physical serial number embedded on a DVD), and a cryptographic hash of the title usage rules.
via[wikipedia]
AACS protected content is encrypted using 128 bit AES!! I mean the security it provides is unbelievable. That is why it takes a regular player about a whole minute to play a HD DVD disk, because it takes so long to decrypt. AACS is very close when compared with its successor CSS (content scrambling system), which is used in DVDs. But, the main difference between them is that under CSS, all players of a given model are provisioned with the same, shared decryption key. Content is encrypted under the title-specific key, which is itself encrypted under each model’s key.
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Now that you have an idea about AACS, let talk about the crack people have been talking about. But, before I begin, I just want to say that people have been making a fuss about this crack because Microsoft Vista has alot to do with it.
As we all know, to find the flaws in any system, you must first find the weakest link and thats were you should start. Last December, the 26th to be precise, someone named “muslix64″ on doom9 forums, was so upset at not being able to play his purchased movies on his monitor attached to his player that he broke the AACS protection just to be able to see his own movies.
He made a utility, and he called it BackupHDDVD, and what it basically does is that it decrypts the files on your HD DVD. Muslix read the AACS’s specs, which were posted on AACS’s website. Then he write a simple java program to decrypt the files after you add the decryption keys to the program. The trick lies in finding the decryption keys!!
He grabbed the decryption keys and then independently decrypted the contents of the drive, which are just files stored in the standard DVD file format, the .udf format (I read somewhere that BackupHDDVD can also decrypt .evo files when give the correct tiltle keys, which is really cool).
Muslix posted a video on youtube of him decrypting an HD DVD movie. But, Warner Bros. asked youtube to remove the movie, and it was removed right away. In this video he was using windows, and a player which was able to decrypt HD DVDs, some say that he was using PowerDVD version 6.5.
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To read more about Muslix’s BackupHDDVD program click here. If you read all Muslix’s posts you will be able to find the keys yourself…
To Download BackupHDDVD click here. Muslix also wrote a documentation to go with the program…
