 - Content Scrambling System (CSS) is a data encryption and authentication method used to protect digital versatile disk (DVD) movies from being illegally copied, distributed, and viewed from other devices, such as computer hard drives. CSS is one of several copy-protection methods currently used in today's DVDs.
The CSS method was developed by members of the DVD Copy Control Association
(DVDCCA). This association includes companies in the U.S. motion
picture industry (members of the MPAA) and the consumer electronics industry.
The Matsushita and Toshiba companies are largely credited with the first main
development efforts of the CSS method for encryption and decryption of DVD
movies.
In general, the CSS method encrypts (scrambles) the video files on a DVD to prevent illegal viewing or copying. In order to view any
video files found on the DVD, the user must use a hardware device that is
CSS-licensed to decrypt, or decode, the data in the video file. One such
hardware device is a DVD-ROM (DVD-read only memory) device that can be
installed with a computer or a specially designed TV in order to view DVD
movies. Another possible device could be the hard disk of a personal computer.
DVD disc manufacturers or DVD-ROM manufacturers must first be licensed to use
CSS before they can produce discs or DVD-ROMs that will successfully encrypt or
decrypt CSS-protected video files. Once a DVD-ROM manufacturer is licensed to
use CSS, the manufacturer receives one of 400 keys which are stored in a locked
section on every CSS-supported disc.
The DVD-ROM then uses this key information to decode the video file on the
DVD and display the related movie. The actual operation of CSS involves the use
of a decryption algorithm that mixes the key information exchanged between the
disc and the hardware device in order to produce a unique key that will
successfully decrypt the movie or video file for viewing.
As with many encryption methods of the past, CSS came under intense scrutiny
in October 1999 when it was reported that a 16-year-old Norwegian programmer cracked the CSS code and posted the decryption method
(quickly coined DeCSS) on the Internet. This action, and the
subsequent postings of DeCSS code elsewhere on the Internet, heralded a series
of lawsuits from the DVDCCA. In response, some pro-DeCSS organizations also
sprouted up to protest what they perceived of as a lack of rights to freely
distribute the reverse-engineered, CSS code for other programming uses.
Lawsuits over the future rights to access the CSS/deCSS code are still being
waged today. The DVDCCA maintains that CSS can be licensed for free to any
manufacturer who agrees to follow the terms of its CSS license.
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Learn more about Disk Encryption and File Encryption |
| CONTRIBUTORS: |
Johnathan Leppert |
| LAST UPDATED: |
24 Jul 2001
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