The present invention exploits the multiple-broadcast capabilities of networks associated with a reliable connection-oriented protocol. The inventive method allows a file to be transferred only once. The data, which represent a large volume of information, use multiple-broadcast channels, whereas the interchanges relating to the control of the quality of the communication use a reliable medium in connected mode. In order to eliminate the unnecessary transfers (network) and activity (server and client), a calculation worked out from all of the file data is performed to identify it definitely.