Content Scramble System

Content Scramble System (CSS)
General
Designers	DVD Forum
First published	Around 1996
Certification	DVD Copy Control Association
Cipher detail
Key sizes	40 bits
Security claims	240
State size	2048 bytes (DVD sector size)
Structure	Linear-feedback shift register-based stream cipher
Best public cryptanalysis
	Defeated in 1999 by DeCSS, 40-bit key size is subject to brute-force attack, effective key size is about 16 bits. This can be brute-forced in about a minute by a Pentium II, or a few seconds by a modern CPU.

The Content Scramble System (CSS) is a digital rights management (DRM) and encryption system employed on many commercially produced DVD-Video discs. CSS utilizes a proprietary 40-bit stream cipher algorithm. The system was introduced around 1996 and was first compromised in 1999.^[1]

CSS is one of several complementary systems designed to restrict DVD-Video access.

It has been superseded by newer DRM schemes such as Content Protection for Recordable Media (CPRM), or by Advanced Encryption Standard (AES) in the Advanced Access Content System (AACS) DRM scheme used by HD DVD and Blu-ray Disc, which have 56-bit and 128-bit key sizes, respectively, providing a much higher level of security than the less secure 40-bit key size of CSS.

^ Frank, Stevenson (2020-09-26) [1999]. "mail1.txt". cs.cmu.edu. Retrieved 2020-09-26.