What Is It Used For?
The main objective of the Encrypted Title Key is to reinforce the discs’ content security during the decryption process of content stored in this media. The content stored in medias like Blue-Ray or HD-DVDs is composed and divided in information units called Titles. The owner of the protected contents, divide this information in the form of one or more Titles. It also provides a license to the player, a series of rules called Usage Rules which will be used later on to decrypt the disc information.
To protect the content, the information units are encrypted using encryption keys called Title Keys. To achieve more security and so that the key obtention process cannot be obtained by player without license, the Title Keys are encrypted giving as a result the Encrypted Title Keys.
The licensed replicator shall select a secret, random Title Key for each Title to be protected. Each Title Key shall be used to encrypt the content of its corresponding Title, as specified for each supported content format elsewhere in this specification. At the replicator’s discretion, a given Title may be encrypted using the same Title Key for all instances of pre-recorded media, or different Title Keys may be used for different instances.
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