Self-Protecting Digital Content
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Self Protecting Digital Content (SPDC) is a copy protection (digital rights management) concept designed by Cryptography Research, Inc. (CRI). CRI worked with Twentieth Century Fox, Sony, and Panasonic to implement this architecture into BD+, which was adopted by the Blu-ray Disc Association for protecting Blu-ray discs.[1][2]
In November 2007, the SPDC business unit and technology was acquired by Macrovision to complement its existing Analog Copy Protection (ACP) and Ripguard technology.[2][1] In 2011, Irdeto acquired SPDC and BD+ from Macrovision (then known as Rovi).[3][4]
SPDC executes code from encrypted content on a Blu-ray player. When releasing new discs, content providers can update the code, adding protections against previous circumvention methods. DRM systems in which keys for encryption and decryption do not change can be attacked with one compromised key, allowing decoding of all content using that key. SPDC attempts to keep future content protected by allowing changes to the DRM in new releases when an existing DRM method is circumvented.
Playback method
If a method of playback used in previously released content is revealed to have a weakness, either by review or because it has already been exploited, code embedded into content released in the future will change the method, and any attackers will have to start over and attack it again.
Targeting compromised players
If a certain model of players are compromised, code specific to the model can be activated to verify that the particular player has not been compromised. The player can be "fingerprinted" if found to be compromised and the information can be used later.
Forensic marking
Code can be inserted into content (digital watermarking) to add information to the output that specifically identifies the player, and in a large-scale distribution of the content, can be used to trace the player (traitor tracing). This may include the fingerprint of a specific player.[citation needed]