The current technological environment with the increasing growth of critical infrastructuresrelationships represents a hard challenge for security solutions. In order to achieve trust among devicesor other networked agents of a critical infrastructure, the definition of completely new methods isrequired. TITAN aims to cover this ground.In fact, it is daring to pursue absolute security for a system, while it is also expensive to implement such asolution. Instead of this approach, trust level assurance is presented as a more natural way to face up tothe problem. In that sense, this project will try to provide a rational model for trust, which could beincorporated to current solutions in order to be possible to implement this new approach for security.The main foreseen research challenges in TITAN are summarized as follows:1. Building trust assurance methodology:The TITAN targeted methodology will provide required steps covering end-to end trust estimationapplied to a critical infrastructure, from the observed system modelling till the trust presentation andmonitoring.2. Distributed Policy Elaboration:TITAN considers the observed infrastructure in a dynamic context which means that policies (at alllevels) will be in the core of the trust estimation processes.3. Multi-agent based Reputation mechanisms:Reputation mechanisms are needed to construct a reputation model to be exploited in the trustestimation4. Aggregation techniques and strategies:Trust values will be estimated based on the knowledge (reputation based) and the experience(learning mechanism) of the agents. Aggregation techniques are needed in order to obtain accuratetrust values.Experimentations will be conducted in specific business case like telecommunication infrastructures inorder to validate the approach.This project aims at enabling such multi-agent trust relationships in end-to-end services using a two-foldapproach:• To define an operational trust model in multi-entities, intra-entity and end-to-endcommunications.• To propose the technological and methodological solutions for the implementation of suchmodel.By its objectives and the proposed approach, the project is directly contributing to the objectives of theCITI department in terms of international recognition in the domain of Services Science as well as to itsopen innovation process in terms of sustainable services targeting the market.