Abstract: A method is provided which allows a service to be enjoyed through a mobile telephone terminal without the need of paying for this service. This can be achieved by allowing a first subscriber to use the credit or subscription of a second subscriber. The subscriber identification cards at least of the two subscribers involved are provided with short range radio communication transceivers and establish a short range communication channel between them so that one card may request the other card to pay for this service and the other card may grant this request through this channel. Then the mobile telephone networks of the cards are informed of the granted request. Before, during and after the grant of the request, the subscriber identification cards remain active and operative in communicating together and with the associated terminals.

Abstract: A server communicates a set of entitlement data representative of the entitlement of a client to access corresponding contents data by using a set of keys and a non-invertible cryptographic function. The cryptographic function is applied to a set of candidate bit strings using the set of keys to find a selected bit string that produces the set of entitlement data as a result of the application of the non-invertible cryptographic function by using the keys in the set. The server and the client share the cryptographic function as well as the set of keys (or the selected bit string). The server transmits to the client the selected bit string (or the set of keys). In either case, the client is thus in a position to apply the cryptographic function to the selected string of bits by using the set of keys, thereby reconstructing the set of entitlement data.

Abstract: A method is provided which allows a service to be enjoyed through a mobile telephone terminal without the need of paying for this service. The can be achieved by allowing a first subscriber to use the credit or subscription of a second subscriber. The subscriber identification cards at least of the two subscribers involved are provided with short range radio communication transceivers and establish a short range communication channel between them so that one card may request the other card to pay for this service and the other card may grant this request through this channel. Then the mobile telephone networks of the cards are informed of the granted request. Before, during and after the grant of the request, the subscriber identification cards remain active and operative in communicating together and with the associated terminals.

Abstract: A server communicates a set of entitlement data representative of the entitlement of a client to access corresponding contents data by using a set of keys and a non-invertible cryptographic function. The cryptographic function is applied to a set of candidate bit strings using the set of keys to find a selected bit string that produces the set of entitlement data as a result of the application of the non-invertible cryptographic function by using the keys in the set. The server and the client share the cryptographic function as well as the set of keys (or the selected bit string). The server transmits to the client the selected bit string (or the set of keys). In either case, the client is thus in a position to apply the cryptographic function to the selected string of bits by using the set of keys, thereby reconstructing the set of entitlement data.