Method of Selective Protection of the Satellite Rebroadcasting of Data Broadcast Publicly and Collected by the Satellite

摘要

The AIS (Automatic Identification System) is a communication system between ships, for example fishing boats, which is used to limit collisions between these ships and that allows maritime traffic in sight of the coasts to be monitored by virtue of coastal stations that listen to the communications. The collection by satellite of these data allows for maritime monitoring far from the coasts and allows the data transmitted to be checked by analysis of the received signal. The maritime monitoring authorities do not want the data concerning, for example, the position of the ships in their territorial waters, collected by satellite, to be broadcast globally. This is because this would enable a user, by listening to the satellite, to know the AIS messages exchanged far from these coasts. The AIS messages contain the position of the transmitting ship, and its identifier, its direction, etc. The invention consists in putting in place an encryption of the data returned from the satellite based on the content of these data. The encryption of the data also enables the authorities to supply the AIS data as a service, possibly a paying service.