advanced access content system (copy protection) (AACS)

Advanced Access Content System (AACS) is a copy protection and digital rights management( DRM) system for recordable and recordable optical discs, specifically HD-DVD and Blu-ray Disc( BD).

AACS can be used equally in personalcomputers(PCs) and in stand-alone consumer electronics devices and protects audio and video content. For encryption, AACS relies on the Advanced Encryption Standard( AES) and encrypts content keys with a 64-bit key, all other content with a 128-bit key. This makes AACS ciphering much more secure against brute force attacks than the Content Scrambling System( CSS) encrypted with a 40-bit key used in DVDs.

Digital rights management includes restricted copying, which can be based on number of copies, time period or drive, drive verification, Internet unlocking or license blocking.

AACS is intended to protect all audio and video content, whether it is delivered on an optical medium, in a video serveronline, or sent as an RF signal.

AACS was developed by the Advanced Access Content System License Administrator (AACS LA), whose members include Intel, Microsoft, Panasonic, Sony, Toshiba, Walt Disney and Warner Brothers. The AACS License Administration is also responsible for licensing and manages one of the key security components, the Media Key Block (MKB), which must be pressed onto storage discs by media manufacturers. It is read into the firmware and is no longer issued for devices whose key has been cracked.