Importance

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Abstract

A disk player that will play only authorized disks. Predetermined data blocks, including those in the lead-in section of the disk which contain content-related data, are processed to derive an authorization code. The authorization code is stored on the disk in encrypted form, using the private key of a public-key cryptosystem pair. The player processes the same disk data to derive a computed code; the player also uses the paired public key to decrypt the encrypted authorization code on the disk. Play of the disk ensues only if the decrypted authorization code matches the computed code. The same technique can be used to control not play of the disk as a whole, but play in certain specific modes.

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First Claim