![]() ![]() It can alter menus and show on-screen messages if some security breach is detected in the player. The content code has full control over all the components involved in playback. Blu-rays with BD+ have special content code which are loaded by the SVM and executed during the playback process. From a player's perspective, a Security Virtual Machine (SVM) needs to be implemented. It is mandatory for players to implement support for BD+, but not all Blu-rays need to be BD+ enabled. This has tempted studios to move over to other forms of DRM such as BD+ and Sony Screen Pass. Note that AACS is based solely on cryptography and, after having been compromised, has the possibility of revoking cryptographic keys as the only means of regaining its effectiveness. With a counterfeit Blu-ray, it is a simple matter of using the VolumeID to trace the place where the piracy took place. The process is tied to the manufacturing facility (which can obtain a license only under strict security considerations). Also, the VolumeID can't be generated by consumers (BD-Recorders don't have the capability to burn a VolumeID). Blu-ray players will not play back protected content without the VolumeID, as it is essential to the decryption process. In addition to AACS, the BDA mandates a BD-ROM mark, which is a physical irregularity on the disc with a 128-bit VolumeID. The net result is that we are currently at AACS v30. This ensures that any snooped data can't be used to get to the original content on the disc. AACS also has a renewal process to prevent attacks similar to those carried out on CSS (with DVDs). In addition to the MKB-Media Key-Title Key combination, PC-based players also have support to generate a Shared Bus Key to encrypt the data inbetween the drive and the software player. AACS does provide some sequence keys to identify a particular device as compromised if one has access to multiple pirated copies of different discs from the same drive. In practice, key revocation is quite rare because device keys could be shared across an entire lineup, making it hard to pinpoint which particular device was compromised. For PC-based playback to be successful, both the player and the drive must not be on the revocation list. The MKB in each disc has a Host Revocation List for software players and a Device Revocation List for hardware drives. The shared key generated by using these two (Media Key) is used to decrypt the Title Key, which is then used to decrypt the audio/video data in the disc. ![]() Each Blu-ray player / device has a Device Key, while discs come with a Media Key Block (MKB). AACS also provides for protected storage through the Managed Copy feature.Ī Popular Webcomic's Take on DRM (c) xkcdĪACS uses 128-bit AES for encryption. In Blu-rays, this DRM scheme is called as AACS (Advanced Access Content System). Protected distribution is enabled by the DRM mechanism in Blu-rays / DVDs. Protected storage is encountered in broadcast content, with its copy flags to allow DVR archiving. Protected transmission is the path to the display device, and it is usually protected by HDCP (over HDMI) or Macrovision in legacy systems. ![]() For the consumer, this entails:Ĭonditional access is applicable to cases where media travels over insecure channels (such as satellite or cable). Content providers mandate the presence of protection schemes at all times when the consumers want to access their wares. ![]()
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