Trust and Reputation Methods and its Applications Carmen Fernandez -Gago

1. Trust and ReputationMethods and itsApplicationsCarmen Fernandez-Gago Department of Computer Science University of Málaga Málaga (Spain)

2. Outline • Concepts of Trust and reputation. Trust and reputation management systems • Applications • Social networks • WSN • Critical Infrastructures

3. Trust and Trust Management Systems • Concept derived from social or economical environments. • Trust is usually specified in terms of a relationship between a • Trustor, the subject that trusts an entity and, • Trustee, the entity that it is trusted. • Trust management systems: • Term used to define a coherent framework for security policies, credentials and trust relationships. Originally designed for access control (PolicyMakerv or KeyNote) • Thereis not a standard way to design a trust management system. Therefore, there are many different systems depending on the context where they are applied to.

4. Reputation Systems • Accordingtothe Oxford dictionary Reputation is what is generally said or believed about a person or thing’s character or standing • Examples of reputationsystems: eBay reputationsystem, … • Relationshipbetweenreputation and trust: • Reputationis a more objective concept • Reputation can beused as an output in orderto derive trust

5. Trust Metrics • Trust metrics: the way to quantify trust: • Our approach: • To caractherize which metrics are more convenient depending on the nature of the problem to solve. • Depending also on the properties that the metrics or operations hold. (task, confidence level) (task, confidence level) (task, confidence level)

6. Trust and Reputation in Social Networks • We plan to use the “measurements” in order to compute trust or reputation value for controling access of users to systems and resources within them • Application to social networks: a user who is a member of different social networks holding a trust or reputation value associated to them: • Objetctive: to compute a unique value to be used in a new social network where the user pretends to gain access

7. Trust in Wireless Sensor Networks • Key aspect for WSN. Very useful for • Detecting faulty or malicious behaviour of peers • Deciding which is the best neighbour to collaborate with • Our approach • To identify the features needed in order to define a good trust management system for WSN • Best practices: use of base station, considering reputation, …

8. Reputation Module for SCADA Systems • The reputation manager will monitor and compute reputation values. Introduction of AAM (Adaptive Assignment Manager) • Reputation will increase or decrease depending on how the operator manages an incidence. It also depends on the criticality of the incidence

9. Conclusions and Future Work • Conclusions • Trust and reputation management systems as a way to control access to systems and resources • Applications: social networks, WSN, Critical infrastructures • Future work • To investigate the use of our metrics in the behavioir of different social networks • Unification of users in different social networks • To test our best practices for WSN in a testbed case • To provide reputation methods at another levels od the critical infrastructures