Generally, in order to protect intellectual property from being copied freely, most commercial pre-recorded DVD/Blu-ray discs have the copy protection for restricting the use rights of the consumers. For example, some consumers will rip DVD to digital format for easier playing, but sometimes will be blocked by the DVD copy protection. Although there are many DVD decrypters and Blu-ray decrypters on the market, the users still are very inconvenient. Therefore, this article will introduce the technology of the DVD/Blu-ray copy protection, you may learn how these copy protection work.
There are four types of the copy protection that frequently used on commercial DVD discs. Here we will introduce these DVD copy protection schemes in turn.
The Analog Protection System is a DVD copy prevention system developed by Macrovision.By adding pulses to analog video signals to negatively impact the AGC circuit of a recording device, this system resulting in garbled and unwatchable in the copied video from the DVD encoded with APS.
The Content Scramble System is a digital rights management (DRM), utilizes a proprietary 40-bit stream cipher algorithm to encrypt the data stored on the DVD disc. If you insert a DVD disc that has been compiled with CSS to the player, the drive will refuse access to logical blocks which are marked as copyrighted. The player must to execute an authentication handshake first. And the authentication handshake is also used to check the disc-key-block and the title-keys.
The Advanced Regional Copy Control Operating Solution is a copy-protection system developed by Sony that is used on some DVDs. As an additional layer, ARccOS is used with Content Scramble System(CSS) together, the system deliberately creates corrupted sectors on the DVD, which cause copying software to occur errors. The bad sector of the DVD disc will bring the inconvenience when we copy the DVD. But there have some superior DVD copy tools can maintain a database of corrupted areas, or analyze the DVD structure to find the unvisited areas of the DVD disc.
CPRM is a copy protection mechanism for restricting the copying or alteration of digital media, this scheme is used for Secure Digital cards(SD) and recordable DVD discs. It is a technical norm delveloped by the 4C Entity, LLC, whose consisting of IBM, Intel, Matsushita and Toshiba. When the protected content is recorded on the DVD disc, the CPRM-compliant recorder will use a media ID to encrypt the recorded data as well as write a Media Key Block(MKB) to be used to decrypt the disc. If the DVD is copied to the new disc or other media, the media ID will be lost or make a error to cause the data cannot be decrypted.
Different from DVD copy protection, Blu-ray disc adopted other copy protection and we will show you the three major copy protection schemes. Furthermore, although many Blu-ray discs were decrypted and uploaded to the Internet, some newest discs cannot be decrypted because the Blu-ray copy protection often upgrading.
The Advanced Access Content System(AACS) is an encryption for control and restrict access and copying of the optical disc. It uses the Advanced Encryption Standard (AES) to encrypt the contents under one or more title keys. In addition to the title keys and the encrypted contents, the disc contains the Media Key Block (MKB), the Volume ID. If these keys have been broken, for protecting the future Blu-ray discs, AACS can revoke the keys which are assigned to the particular players.
BD+ is a component of the Blu-ray Disc Digital Rights Management system. It is a virtual machine embedded in authorized players. The stream files of Blu-ray disc are encrypted by using AACS and then they will be destroyed randomly. At the same time, preserving the instructions about how to repair the mangled files on the discs as special BD+ instructions. These instructions run in the BD+ virtual machine.
Cinavia is an advanced technology of copy protection that works on Blu-ray discs. This technology inserts the anti-piracy data into the audio track and hides it, know as the audio watermark and this encrypted data is an audio signal but it is inaudible. When the Cinavia signal was struck, the audio track will mute or stop to playback.