Method for the secure exchange of data over an ad-hoc network implementing an xcast broadcasting service and associated node

A method, implemented in an ad-hoc network implementing an Xcast broadcasting service for a secure exchange of a data from a sender node, sending the data, to a list of receiver nodes, receiving the data, a communication topology of the network being defined by a communication graph, wherein the method comprises:

• providing a security graph of the network, that defines a security topology for the network;
• routing, on the basis of the security graph, the data between the sender node sending the data and each receiver node receiving the data along a secure route on the security graph;
• generating, between a relay node and a subsequent relay node of the secure route, an appropriate message, containing the data protected in accordance with a security association shared between the said relay node and the subsequent relay node;
• and
• routing, on the basis of the communication graph, the message from the relay node to the subsequent relay node along a communication route on the communication graph.