  In this paper, we propose and evaluate a distributed protocol to manage trust
diffusion in ad hoc networks. In this protocol, each node i maintains a \trust
value" about an other node j which is computed both as a result of the
exchanges with node j itself and as a function of the opinion that other nodes
have about j. These two aspects are respectively weighted by a trust index that
measures the trust quality the node has in its own experiences and by a trust
index representing the trust the node has in the opinions of the other nodes.
Simulations have been realized to validate the robustness of this protocol
against three kinds of attacks: simple coalitions, Trojan attacks and detonator
attacks.
