Method and a system for receiving a multimedia signal, a cryptograophic entity for said reception method and system, and a method and a black box for producing said cryptographic entity

摘要

This method of receiving a multimedia signal scrambled by means of a control word uses a first cryptographic entity that can be connected to any one of P second cryptographic entities to form part of a device for receiving the scrambled multimedia signal. Only second cryptographic entities of a group of N second cryptographic entities selected from a wider set of P second cryptographic entities use a session key obtained by diversifying a root key identical to the root key used to obtain the session key of the first cryptographic entity.