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=== Decryption process ===
To view the movie, the player must first decrypt the content on the disc. The decryption process is somewhat convoluted. The disc contains 4 items—the Media Key Block (MKB), the Volume ID, the [[Encrypted Title Key|Encrypted Title Keys]], and the Encrypted Content. The MKB is encrypted in a subset difference tree approach. Essentially, a set of keys are arranged in a tree such that any given key can be used to find every other key except its parent keys. This way, to revoke a given [[Device Keys|device key]], the MKB needs only be encrypted with that device key's parent key.
Once the MKB is decrypted, it provides the Media Key, or the ''km''. The ''km'' is combined with the Volume ID (which the program can only get by presenting a cryptographic certificate to the drive, as described above) in a one-way encryption scheme (AES-G) to produce the Volume Unique Key (''Kvu''). The ''Kvu'' is used to decrypt the encrypted title keys, and that is used to decrypt the encrypted content.<ref name=arstechnica-aacs /><ref>{{cite web
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