Patent ID: 7461406

Claim:
A recording system configured to apply access control processing to input data content using a set of one or more content keys and to record access-controlled data content on a computer readable storage medium, said recording system comprising: an encryption apparatus having encryption logic configured to encrypt portions of said input data content in dependence upon said set of content keys to generate encrypted input data content; an access control memory device configured to store securely information from which a private key of a private key/public key pair associated with a data content recording user or user group is derivable, said encryption apparatus and said access control memory device co-operating to provide a content access control data generator configured to generate content access control data, said content access control data including at least one encrypted version of a respective subset of said set of content keys, said content access control data including content recorder access control data and default access control data, said content recorder access control data being generated in dependence upon the public key corresponding to the private key derivable from information stored on said access control memory device and said default access control data being generated in dependence upon one or more public keys of respective default public key/default private key pairs defined as default public keys in said access control memory device, said default access control data providing the same level of access to said input data content via one of said default private keys as the level of access available to said data content recording user or user group, said content access control data generator configured to always encrypt the full set of content keys using the one or more default public keys, wherein said encryption apparatus is configured to record said encrypted input data content on said computer readable storage medium together with said content recorder access control data and said default access control data.