A generic framework towards trust building in self-organized, peer, networks

1. A generic framework towards trust building in self-organized, peer, networks Giannis F. Marias, Vassileios Tsetsos, Odysseas Sekkas and Panagiotis Georgiadis Dept. of Informatics and Telecommunications, University of Athens SecPerU 2005 July 14 2005 Santorini, Greece

2. Presentation Structure • Introduction • ATF Architecture • Simulations, Future Work and Conclusions SecPerU 2005, Santorini, Greece

3. Self-organized networks • MANETs • Ad hoc collaborations • No infrastructure available • Many threats from selfish, malicious or hacker nodes • Advanced needs for QoS and security SecPerU 2005, Santorini, Greece

4. Trust Management • A new paradigm for security and QoS solutions in open systems • Involves (among others): • recommendations exchange • reputation building/fading • Does not require central authorities • Many different trust management schemes have been proposed SecPerU 2005, Santorini, Greece

5. Motivation • Trust management schemes seem suitable for ad hoc collaborations • Those proposed for MANETs are too specialized • Those proposed for middleware services are too complex to apply to MANETs • Belief networks, probabilistic methods • A lightweight flexible framework is needed for assessing the trustworthiness of nodes  ATF (Ad hoc Trust Framework) SecPerU 2005, Santorini, Greece

6. Presentation Structure • Introduction • ATF Architecture • Simulations, Future Work and Conclusions SecPerU 2005, Santorini, Greece

7. Trust Builder Trust Policy Trust Matrix TS1 TS2 RFTS Reputation Manager Network and Application Stack Overall Architecture ATF is a trust evaluation and advertisement framework NOT a cooperation enforcement technique NOT a security framework SecPerU 2005, Santorini, Greece

8. Trust Sensors • Every node provides functions to other nodes • Packet forwarding, routing, naming services, … • Trust Sensors evaluate the quality of these functions in a node’s neighborhood – i.e., capture the direct evidence • Observation of neighbors’ behavior • Comparison to reference/ideal behavior • Quantification of the difference to Success/Failure SecPerU 2005, Santorini, Greece

9. Reputation Manager • On-demand recommendations exchange • The nearest and most trustworthy recommenders are selected based on the TrustSpan Algorithm • Recommendations are requested only when there are insufficient direct evidences SecPerU 2005, Santorini, Greece

10. TrustSpan algorithm • Packet forwarding for one- and two-hop neighbors is monitored through AODV headers and MAC overhearing • At most Ntrusted recommenders are selected • They are detected with a special TS, called RFTS (Rec. Function Trust Sensor) • The algorithm is invoked periodically and only for target nodes with less than M direct interactions SecPerU 2005, Santorini, Greece

11. Trust Builder • Main components: • Direct evidence (DE) • Recommendations (REC) • History of interactions • Subjective factor (SUB) • The values for all open parameters are defined in the Trust Policy of each node • Trust Values are assigned per (node, function) in a Trust Matrix SecPerU 2005, Santorini, Greece

12. Trust Computation (I) • Time is discrete and counts separately for each (node, function) according to the direct evidence • w and H are defined in Trust Policy so as to decrease the trust fluctuations without losing sensitivity SecPerU 2005, Santorini, Greece

13. Trust Computation (II) α, b, SUB:defined in Trust Policy SecPerU 2005, Santorini, Greece

14. SUB • SUB is a time function in the range [0,2] • It allows for the introduction of subjective criteria in trust assessment • SUB=0  distrust always • SUB=1  use the default ATF trust scheme • SUB=2  be enthusiastic • Ideally used for modeling more complex time-variant behaviors and trust strategies • Example strategy: do not trust the function X of any node until there are W successful interactions SecPerU 2005, Santorini, Greece

15. Presentation Structure • Introduction • ATF Architecture • Simulations, Future Work and Conclusions SecPerU 2005, Santorini, Greece

16. Simulations (I) • We have already performed some simulations using J-Sim and AODV as the routing protocol • We deal with the packet forwarding function • The first results are quite satisfactory regarding overheads of TrustSpan and identification time for selfish nodes • Simulation results will be published soon SecPerU 2005, Santorini, Greece

17. Simulations (II) f = packet forwarding #nodes = 50 max speed = 1.2 m/s packet rate = 4 pkts/s area = 300x300 m2 Averaged identification times for 10 selfish nodes SecPerU 2005, Santorini, Greece

18. Future Work • Test ATF with more high-level functions/protocols • Assess its robustness and accuracy through extensive simulations • Investigate the effects of individual trust strategies in the trust establishment process (implemented through the SUB component) SecPerU 2005, Santorini, Greece

19. Conclusions • ATF is a generic framework in a sense that is function-agnostic • It is lightweight as it entails only simple mathematical computations • It involves a subjective component as dictated by trust-related research in other disciplines • e.g., psychology, cognitive science • The large number of Trust Policy parameters enable flexibility in trust building SecPerU 2005, Santorini, Greece

20. The end Thank you for your attention!!! Questions??? SecPerU 2005, Santorini, Greece