An apparatus and associated methodology are provided for distributing individual keys for deciphering scrambled digital data transmitted by a broadcasting system to a plurality of terminals connected to a data exchange network. The broadcasting system includes at least one portal designed to provide the individual keys, at least one scrambling platform and at least one server designed to broadcast the scrambled data. The scrambling period of the data is divided and transmitted into a succession of encoding periods CP.sub.i, each defining a period of validity of an individual key Ki. A set of individual keys are supplied at each connection of a terminal to the portal. The set of individual keys includes at least one key corresponding to the encoding period CP.sub.i, and at least one key corresponding to the encoding period CP.sub.i+1. The terminal has also provided the date of a future connection to collect a set of deciphering keys corresponding to at least a future encoding period if the continuation of the access is authorized.