What
is CSS? ( Content Scrambling System for DVD Video )
From Wikipedia
Content-Scrambling System (CSS) is an encryption system used
on some DVDs. It uses a weak, proprietary 40-bit encryption
algorithm. The system was introduced circa 1996.
The CSS key sets are licensed to manufactors who incorporate
them into products such as DVD drives, DVD players and DVD
movie releases. Most DVD players are equipped with a CSS
Decryption module. CSS key is a collective term for authentication
key, disc key, player key, title key, second disk key set,
and/or encrypted key.
In October 1999, the algorithm was reverse engineered by
Jon Johansen and DeCSS was released. The CSS algorithm was
soon revealed to be easily susceptible to a brute force attack.
The weakness of the protection is due to US government crypto-export
regulations, apart from being an example of the trusted client
problem.
Specification of CSS
Authentication is a process for a DVD drive and CSS Decryption
module to recognize (or authenticate) each other. It is
necessary before reading data from DVD discs. Authentication
keys are used for this process.
Title keys are used for scrambling and descrambling actual
data on DVD discs called titles. A title could be a complete
motion picture, a trailer or similar self-contained unit.
Disc keys are used for decrypting title keys on DVD discs.
Player keys are used for decrypting disc keys on DVD discs.
Each DVD player manufacturer is allocated one of approximately
400 player keys to incorporate in its players.
