Nagravision S.a.

Patrick Bertholet

Corinne Le Buhan

Marco Sasselli

Maxime Goeke

Corine Le Buhan

The objective of the present invention is a storage method in a decoder of an event encrypted by control words that guarantees the access to this event at whichever moment, even if certain keys of the system have changed for security reasons. This objective is achieved by a storage method of an event encrypted by control words in a reception and decryption unit connected to a security unit, said control words and the necessary rights being contained in management messages encrypted by system keys, comprising storing the encrypted event as well as the control messages in the storage unit, and storing in the storage unit the system keys encrypted by a predefined local key stored in the security unit.

Secured storage method of encrypted data on a personal digital recorder

As television programs increases, it becomes necessary to find means for rapidly accessing the users' preferred programs. Furthermore, television programs are addressed to different types of users such as children and adults. The proposed system processes a program grid comprising at a higher level the whole information on programs and at a lower level, information specific to a users group as well as parameters defining a user profile. The parameters are divided into several sets of parameters, each set corresponding to a filter layer allowing selecting a category or categories of required information. The first layer, defining a global restrictive filter, is defined by an administrator of the system and the following layers, defining a filter specific to a users group and containing filtering short commands, are defined by at least one member of the users group.

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Lausanne, Switzerland

Patrick Bertholet