Advanced languages and techniques for trust negotiation.

The Web is quickly shifting from a document browsing and delivery system to a hugely complex ecosystem of interconnected online applications. A relevant portion of these applications dramatically increase the number of users required to dynamically authenticate themselves and to, on the other hand, to identify the service they want to use. In order to manage interactions among such users/services is required a flexible but powerful mechanism. Trust management, and in particular trust negotiation techniques, is a reasonable solution. In this work we present the formalization of the well known trust negotiation framework Trust-X, of a rule-based policy definition language, called X-RNL. Moreover, we present the extension of both the framework and of the language to provide advanced trust negotiation architectures, namely negotiations among groups. We also provide protocols to adapt trust negotiations to mobile environments, specifically, we present protocols allowing a trust negotiation to be executed among several, distinct, sessions while still preserving its security properties. Such protocols have also been extended to provides the capability to migrate a ongoing trust negotiation among a set of known, reliable, subjects. Finally, we present the application of the previously introduced trust negotiation techniques into real world scenarios: online social networks, critical infrastructures and cognitive radio networks.