the aim of the present invention consists of reducing the switching time from one reception channel to another . in fact , this reduction will be particularly discernable since the number of different rights stored in a security module of a multimedia unit or decoder is high . when a user selects a service among those proposed by an electronic programs guide , an access control module explores a stored service information table in order to extract an access condition associated to the service . this access condition allows determining an index in a rights table stored in the access control module of a right that fulfills the access condition . the access control module transmits to the security module the index thus determined alone or accompanied by a control message . this index allows the security module to find quickly the right that it compares afterwards with the access condition included in the control message after decryption of the latter .