Trust management for distributed heterogeneous systems by using linguistic term sets and hierarchies, aggregation operators and mechanism design

The current trend in system development is integrating already-existing systems in order to realize largescale infrastructures. Several of these infrastructures exhibit stringent security requirements that must be handled by properly managing the trust relationships within both the different systems involved, and all the external entities interacting with the integrated infrastructure. Trust management is made complex by the intrinsic heterogeneity characterizing the integrated systems. To handle such a heterogeneity, we propose the application of fuzzy logic, combining it with proper means to deal with heterogeneous fuzzy sets. We present a technique to combine qualitative and quantitative specifications of trust scores aiming at periodically computing a new trust degree, by also considering reputation scores collected from other systems within the infrastructure. Last, we applied the game theory in order to promote truth-telling behavior during the process of reputation information collection. We finally present some experimental results showing the effectiveness of our approach in heterogeneous distributed environments.