Digital Rights Management
Blu-ray Disc has an experimental digital rights management (DRM) feature called BD+ which allows for dynamically changing keys for the cryptographic protections involved. Should the keys currently in use be "cracked" or leaked, manufacturers can update them and build them into all subsequent discs, preventing a single key discovery from permanently breaking the entire scheme. Blu-ray Disc also mandates a Mandatory Managed Copy system, which allows users to copy content a limited number of times, but requiring registration with the content provider to acquire the keys needed; this feature was originally requested by HP. [10]
The lack of a dynamic encryption model is what made standard DVD's Content Scramble System a disaster from the industry's perspective: once CSS was cracked, all standard DVDs from then on were open to unauthorized decryption. However this controversial technology, together with Self-Protecting Digital Content (SPDC), can allow players judged "bad" to be effectively disabled,[11] preventing their use by their purchaser or subsequent owners.[12] See Advanced Access Content System (AACS).
The Blu-ray Disc Association also agreed to add a form of digital watermarking technology to the discs. Under the name "ROM-Mark", this technology will be built into all ROM-producing devices, and requires a specially licensed piece of hardware to insert the ROM-mark into the media during replication. All Blu-ray Disc playback devices must check for the mark. Through licensing of the special hardware element, the BDA believes that it can eliminate the possibility of mass producing BD-ROMs without authorization.
In addition, Blu-ray Disc players must follow AACS guidelines pertaining to outputs over non-encrypted interfaces. This is set by a flag called the Image Constraint Token (ICT), which would restrict the output-resolution without HDCP to 960×540. The decision to set the flag to restrict output ("down-convert") is left up to the content provider. According to CED Magazine, Sony/MGM and Disney currently have no plans to down-convert, and Fox is opposed to it as well. Warner Pictures is a proponent of the ICT, and it is expected that Paramount will also implement it. Other studios releasing Blu-ray Disc content have not yet commented on whether or not they will use down-conversion. None of the titles released as of Dec 2006 include the use of the ICT. AACS guidelines require that any title that implements the ICT must clearly state so on the packaging.
In January 2007, it was reported that the AACS portion of the DRM protection had been cracked using technique similar to one used against the implementation of the same system on HD DVD.