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

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

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

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

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

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

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

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

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

TrustSpan algorithm Packet forwarding for one- and two-hop neighbors is monitored through AODV headers and MAC overhearing At most N trusted 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

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

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

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

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

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

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

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

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

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

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