Abstract: The invention concerns a particular structure of enhanced short message, and a method for synchronizing and ensuring the security of exchanged enhanced short messages having this structure. Conventionally, an enhanced message is transmitted by a message service centre to a subscriber identification module (or SIM module) of a mobile station. The body (2) of this enhanced message contains in particular a first field (3) for remote commands pertaining to a remote application. This body (2) also contains a second field (4) for storing the current value of a synchronizing counter, to be compared to a previous value of the synchronizing counter, stored in the SIM module. The body (2) can contain another field (6) for storing a certificate, the body signature, for proving the authenticity of the enhanced message and the identity of its transmitter. The enhanced message is accepted or refused by the SIM module depending on the coherence of these values with the internal status of the SIM module.

Abstract: A communication system comprising multiple terminal equipment (1), each consisting of a terminal (4) cooperating with a microprocessor-driven user card (SIM module; 5). Each user card includes data memory (8) comprising a plurality of objects and serving as medium to at least two separate applications, the user card comprising a microprocessor (6) and ROM (7) for executing instructions pertaining to the applications. Each object contained in the user card data memory is associated with a first defined access control policy by a set of first access conditions. Each object is also associated with at least another access control policy defined by a set of at least one alternative access condition. Each alternative access condition is applicable, for the object, to group of at least on instruction pertaining to the application(s) using the other defined access control policy.