What is "backuphddvd"

BackupHDDVD is a small computer software utility program available in command line and GUI versions which aids in the decryption of commercial HD DVD discs protected by the Advanced Access Content System. It is used to back up discs, often to enable playback on hardware configurations without full support for HDCP. The program's source code was posted online, but no licence information was given.

Written by an anonymous programmer using the handle Muslix64, BackupHDDVD is distributed with none of the cryptographic keys necessary for decryption. Users wanting to use the software to decrypt a protected disc's contents must obtain the appropriate keys separately, a task with which neither the original author nor his or her versions of BackupHDDVD assist.

BackupHDDVD represented the first known successful attack against AACS. The utility circumvents content protection by decrypting video files directly with AES, the underling cryptographic cipher used by AACS. Using this technique, BackupHDDVD is able to completely bypass the AACS chain of trust, rendering it immune to revocation. The cost of this immunity is that users are forced to rely on keys leaking from commercial player software to use BackupHDDVD with new discs.