1. A client device comprising: a memory for storing a current version certificate, the current version certificate having a corresponding current version; at least one device interface for communications to and from a certification authority and a local station; a processing module, coupled to the memory and the at least one device interface, characterised in that it is adapted to: receive a current instance certificate, via the communications from the certificate authority, wherein the current instance certificate includes the current version identifier of the current version certificate that identifies the current version of the current version certificate and distinguishes the current version from other version certificates and a current instance public key corresponding to a current instance private key; wherein the current version identifier can be used to indicate revocation of planal client devices comprising version certificates having said current version identifier; send the current instance certificate, via the communications to the local station, during a registration with the local station; generate a request for video content and sends the request via the communications to the local station for authentication based on the current instance certificate and the current version identifier; receive first encrypted data, via the communications from the local station, wherein the first encrypted data includes a content key that is encrypted via the current instance public key; and receive second encrypted data via the communications from the local station, wherein the second encrypted data includes the video content that is encrypted via the content key. a memory for storing a current version certificate, the current version certificate having a corresponding current version; at least one device interface for communications to and from a certification authority and a local station; a processing module, coupled to the memory and the at least one device interface, characterised in that it is adapted to: receive a current instance certificate, via the communications from the certificate authority, wherein the current instance certificate includes the current version identifier of the current version certificate that identifies the current version of the current version certificate and distinguishes the current version from other version certificates and a current instance public key corresponding to a current instance private key; wherein the current version identifier can be used to indicate revocation of planal client devices comprising version certificates having said current version identifier; receive a current instance certificate, via the communications from the certificate authority, wherein the current instance certificate includes the current version identifier of the current version certificate that identifies the current version of the current version certificate and distinguishes the current version from other version certificates and a current instance public key corresponding to a current instance private key; wherein the current version identifier can be used to indicate revocation of planal client devices comprising version certificates having said current version identifier; send the current instance certificate, via the communications to the local station, during a registration with the local station; generate a request for video content and sends the request via the communications to the local station for authentication based on the current instance certificate and the current version identifier; receive first encrypted data, via the communications from the local station, wherein the first encrypted data includes a content key that is encrypted via the current instance public key; and receive second encrypted data via the communications from the local station, wherein the second encrypted data includes the video content that is encrypted via the content key.