Access control for digital content

摘要

A data storage arrangement operable to apply access control processing to input data in dependence upon a public key of a public key/private key pair. The arrangement comprises an encrypting apparatus and a plurality of removable memory devices (e.g. smart cards, MagicGate (RTM) Memory Stick (RTM), Secure Digital cards etc.) connectable to the encrypting apparatus via an interface. The encrypting apparatus stores a local copy of a user directory which is identified by a local version identification tag and lists a user identifier and an associated public key for each of a plurality of authorised users. Each removable memory device stores an external copy of the user directory and has an associated external version identification tag. The encryption apparatus also has encryption means for encrypting at least portions of the input data content in dependence on a public key derived from either the local or the external user directory. The encrypting apparatus has means for comparing the local version identification tag with the external version identification tag and when it is detected that these differ for updating, the plurality of user identifiers, respective public keys and version identification tag of the less recent version of the user directory to correspond to the more recent version of the user directory. The encrypting apparatus may be audio and/or video capture or processing apparatus (e.g. digital camcorder or digital camera). The arrangement can be used to propagate current user directory information (digital rights) through a system implementing digital rights management (DRM).