Archive for March, 2007

Mar 26

Xbox 360 kernel working exploit ?

in Hardware, In Internet and Quick Note. 1 Comment Printable version Printable version

In a previous post I reported that for the first time an vulnerability was found and disclose or the XBOX 360 kernel. I also predict that this will open the door to homebrew on Xbox360. It seem’s that this day as arrived, as today a video that show an Ubuntu distribution booted on the Xbox360 as been released. It use a patched copy of King kong. The use of King Kong seem’s coherent as it is know that it shader are modable. The video is convaincing. Hence there is a strong probability that this is not a hoax.

Having a Linux on the xbox 360 as two majors benefits:

  1. You have a 3 core computer for only 400 euro.
  2. It is possible, as for the first xbox, to install a media center on it.

Here is the video from youtube:

Mar 22

Analysis of the DVB Common Scrambling Algorithm [Article Review]

in Confidentiality, In Publications and Technology. 0 Comments Printable version Printable version

The Common Scrambling Algorithm (CSA) is the standard algorithm to encrypt data in Digital Video Broadcasting system (DVB). DVB is the standard used in every TV broadcasted via satellite such as Digital+, Canal Sat, TPS, Premiere .

It should not be confused with the Conditional Acess (CA) which is used to ensure that only authorized customers have access to channels. Popular CA include Connax, Viaccess, Nagravision, Irdeto. CA is used by providers, such as TPS, to transmit securely Common Word (CW) that is used by the CSA to decipher DVB content. CW are usually reseeded every 10-60 seconds.

If the CA used depends of providers choice, the CSA algorithm is used for every DVB system. In other word, a flaw in CSA will affect every DVB system regardless of the provider. Hence this is the most vulnerable point of DVB system.

From 1994 to 2002 the CSA algorithm was not public. After the release of a software called FreeDec it was reversed. It unique feature is it use a bloc cipher and a stream cipher algorithm. The reason beyond this feature is unknown. There is no obvious security requirement that justify such design.

Two papers were released on the CSA security. “Analysis of the DVB Common Scrambling Algorithm” was the first. It has been published for the Conference on Communications and Multimedia Security 2004. Written by R. Weinmann and K. Wirt it provide a great overview of the algorithm along with various security evaluation on it. This is a must read paper if you are interested in DVB security. It is also interesting for cryptographic security because of it design.

Diagrams and explanations are clear and it is a pleasant article to read. Stream Period analysis is well down. I regret that the paper was so short, in particular the part on the bloc cipher analysis.

The second article published on the subject was by the same other and present an injection fault that require to change a bit during the execution. Such threat is unlikely to append so it is only here for reference. I suggest to stick with the first that present in more details the algorithm and have a more general analysis of CSA security

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