Subscriber identity module and associated broadcasting server adapted for managing programs having undefined duration

An identity module of a subscriber to a charged programme broadcasting service, said module being intended to be integrated in or connected to a terminal, said programmes being broadcast in the form of at least one message having an enciphered content and at least one key message, said at least one key message carrying in particular a timestamp and an encoded value of a traffic key enabling said terminal to decipher said messages having an enciphered content,

• said module including:
• a memory for storing and simultaneously delivering a service key and a period of validity associated with said service key;
• a key decoding means for deducing the value of the traffic from the encoded value, using said service key;
• a validity controlling means for delivering to the key decoding means the service key if, and only if, the timestamp is included in the period of validity of such service key;
• a dispatching means for receiving said at least one key message, extracting and transmitting the timestamp, the encoded value of the traffic key respectively to the validity control means and key decoding means;
• wherein:
• the dispatching means is adapted for extracting and transmitting to the validity control means, information on the extension of the period of validity contained in said at least one key message, certifying that the programme is a programme extension;
• and
• the validity controlling means is adapted for interpreting said information on the extension of the period of validity and delivering the service key independently of the value of the timestamp if, and only if, said information certifies that the programme is a programme extension.