Philips has released updates of the DVD+RW and DVD+R Video Format Specifications (versions 3.0) as well as the VCPS (Video Content Protection System) Version 1.3.
The VCPS Protection
On 4 November 2003, the United States FCC published its decision on the Broadcast Flag, meaning that after 1 July 2005, digital video recorders in the United States will have to encrypt recorded TV broadcasts that carry the flag. In Japan, a similar regulation already requires the encrypted recording of digital TV broadcast signals. The rules for digital outputs in Japan are described in Operational Guidelines for Digital Terrestrial Television Broadcasting and Operational Guidelines for Digital Satellite Broadcasting. More information is available at http://www.arib.or.jp/english/
To fulfil these encryption requirements, Philips and HP have jointly developed the VCPS technology. VCPS is a technology for encrypting video recordings on DVD+R/+RW discs. VCPS enables direct digital recording of "copy-once" content from satellite and cable sources.
The Video Content Protection System (VCPS) allows cable content marked as "copy once" to be burned onto VCPS-enabled DVD+R and DVD+RW optical digital media.
The implementation of VCPS in DVD+R/+RW equipment and discs is not mandatory, but equipment and discs without VCPS capability are unable to record or playback digital TV broadcast in the USA that is protected with the Broadcast Flag.
Encrypting MPEG2 video streams
VCPS protects the video recording by encrypting the MPEG2 streams on DVD+R, DVD+RW and DVD+R DL discs. The main techniques are:
- A 128-bit AES cipher encrypts the disc sectors that contain MPEG2 video.
VCPS-capable blank DVD+R/+RW discs contain a Disk Key Block, coded in the track wobble (ADIP).
- VCPS-capable recording equipment and playback equipment need a Device Key embedded in the product.
- VCPS-capable recording and playback equipment use their Device Key to calculate the encryption key of the MPEG2 stream from the Disk Key Block.
The disc
The Disk Key Block that is coded in the track wobble (ADIP) of VCPS-capable recordable discs is written together with the address information on the stampers that are used in replicating blank recordable discs.
Note that a VCPS-capable disc can also record unprotected video. It is also possible to mix unprotected and protected recordings on the same disc. The unprotected recordings in the DVD+VR format will play in all DVD players, while the protected recordings obviously need VCPS-prepared playback equipment.
Implementation of VCPS on players and recorders
A VCPS-capable DVD recorder or DVD player uses its Device Key to calculate the encryption key for the MPEG2 video. Each sector that contains MPEG2 video is encrypted.
Encryption and decryption in PC implementations is performed in almost the same way as in a stand-alone DVD-recorder. Each software application requires a Device Key to calculate the encryption key. Encryption and decryption of the video is carried out by the software. The only difference is that PC software and the PC drive are required to perform an authentication protocol in which the optical drive proves that it is a genuine optical drive and not a software emulation of an optical drive. The optical drive also needs a Device Key to perform this authentication, and the software applications need a so-called Application Key Block in addition to its Device Keys. Currently, Nero Burning ROM, CyberLink PowerDVD and other software packages are compatible with the VCPS protection.
The updated DVD+RW Video Format Specifications, Version 3.0 have been released today by Philips. The VCPS book can be downloaded from the
Philips Licensing website.