Abstract: System for protecting data on a data carrier on which is stored an accessible medium code and data only accessible after presenting an access code, comprises: a) an apparatus incorporating, a programmed processor, a user interface, a mobile telephone incorporating a SIM-card, b) a central station incorporating a further programmed processor cooperating with a number of memories storing valid medium SIM and access codes. The processor can be connected through the telephone and a suitable communication network to the further processor in the central station whereby the SIM-code of the telephone and the medium code of the carrier are transferred to the further processor to be processed into an access code. The resulting combination of codes is compared with codes stored in memories, and in case of a valid code combination a coded access permission is sent to the processor enabling the software to read data from the data carrier.