Abstract: A clearinghouse authorizes a content provider to use a scrambler to scramble content using a content ID. The content provider provides the scrambled content to a content consumer. If the content consumer has a valid authorization, it can use a content descrambler and the content ID to descramble and access the content. Authorization takes the form of a electronically signed authority message including a device ID and the content ID. The authorization is valid for the content consumer if the device ID matches a corresponding value in the descrambler. The scrambler implements an irreducible scrambling function that can be performed quickly in special-purpose hardware but not on general purpose hardware or software. The scrambler and descrambler can also be used to authenticate the content consumer.