Content Scramble System: Difference between revisions
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'''Content Scramble System''' ('''CSS''') is a [[Digital Rights Management]] (DRM) scheme used on almost all commercially produced [[DVD]]-Video discs. It utilizes a |
'''Content Scramble System''' ('''CSS''') is a [[Digital Rights Management]] (DRM) scheme used on almost all commercially produced [[DVD]]-Video discs. It utilizes a relatively weak, [[proprietary]] [[40-bit encryption|40-bit]] [[stream cipher]] algorithm. The system was introduced around 1996 and has subsequently been compromised. |
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The CSS key sets are licensed to manufacturers who incorporate them into products such as [[DVD drive]]s, DVD players and DVD movie releases. Most [[DVD player]]s 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. |
The CSS key sets are licensed to manufacturers who incorporate them into products such as [[DVD drive]]s, DVD players and DVD movie releases. Most [[DVD player]]s 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. |
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Revision as of 21:04, 26 October 2007
Content Scramble System (CSS) is a Digital Rights Management (DRM) scheme used on almost all commercially produced DVD-Video discs. It utilizes a relatively weak, proprietary 40-bit stream cipher algorithm. The system was introduced around 1996 and has subsequently been compromised.
The CSS key sets are licensed to manufacturers 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, Jon Lech Johansen and two people who remained anonymous reverse engineered the algorithm 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. The CSS algorithm has been superseded by the Cryptomeria cipher in newer DRM schemes such as CPRM/CPPM, or by AES in the AACS copy-protection schemed used by HD DVD and Blu-ray Disc.
Specification
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 DVDs. Authentication keys are used for this process.
Title keys are used for scrambling and descrambling actual data on DVDs 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 DVDs.
Player keys are used for decrypting disc keys on DVDs. Each DVD player manufacturer is allocated one of approximately 400 player keys to incorporate in its players.
While most CSS decrypting software is used to play DVD films, other non-playing software (such as DVD Decrypter, AnyDVD, DVD43, Smartripper and DVD Shrink) allows a region-specific DVD to be copied as an all-region DVD. Such software is also able to remove Macrovision, Content Scrambling System (CSS), region codes, and disabled user operations (UOPs).
See also
- DVD Copy Control Association
- Advanced Access Content System
- DeCSS, DVD Decrypter, Smartripper and libdvdcss
- Content Protection for Prerecorded Media (CPPM)
- Fair use
- ARccOS: an additional form of DVD copy protection