The invention aims at ensuring the security of personal data from a remote server to a final user carrying out purchasing operations, for example. This is achieved by a system comprising a remote-control unit and a multimedia unit provided with means to be connected to a telecommunication network, said multimedia unit comprising a central unit, a non-volatile storage and an input for signals from the remote-control unit. The invention is characterised in that the remote-control unit comprises a unique identification code and means for encrypting data to be transmitted to the multimedia based on said unique code, the multimedia unit comprising means for decrypting the received data.