|
|
|
|
|
|
DVD Copy ProtectionDigital Copy ProtectionThe Content Scrambling System (CSS) is used to scramble the audio/video data on a DVD-Video disc. Each video title set (VTS) can be selectively scrambled using a unique key. Each unique title is assigned one Disc Key and up to 99 Title Keys (one per VTS), which are stored on the disc in encrypted form. In the decoder, the original keys are obtained by decryption and used to descramble the data. Only the video data is encrypted. For DVD-ROM drives, the MPEG-2 decoder challenges the drive and receives the necessary keys for decryption. This ensures that only approved hardware/software can be used. The keys used should be unique for every disc title and are encrypted by the CSS Licensing Authority and, usually, the scrambling is carried out during glass mastering. Security is vital and the keys used plus the encryption algorithms must be kept secret. Only those companies involved in designing hardware and software for CSS encoding and/or decoding need information on the algorithms and systems used. DVD Analogue Copy ProtectionThe Macrovision Analogue Protection System (APS) is based on Macrovision version 7.0 and is used to distort the composite video output to prevent recording and playback on VHS. This does not extend to RGB or YUV outputs for which new methods are required and are currently being investigated. Adding APS to a DVD-Video disc requires the
content owner to become licensed by Macrovision and the authoring studio
to set a flag to enable APS in the player. |
|
