As an important concept in network security, trust is interpreted as a set of relations among agents participating in network activities. Trust relations are based on previous behaviors of agents as well as on trust documents. We present our results on distributed trust management in MANET. The trust information or evidence used to evaluate trustworthiness is provided by peers, i.e., the agents that form the network. We describe first a new trust document distribution scheme based on swarm intelligence. Then we describe various methods for distributed trust evaluation and the associated trust (and mistrust) 'spreading' dynamics. Under such dynamics the whole network evolves as the local interactions iterate from 'isolated trust islands' to 'a connected trust graph.' Our interest is to discover rules and policies that establish trust-connected networks using only local interactions, to find the conditions under which trust spreads to a maximum set, and to find the parameters (e.g., topology type) that speed up or slow down this transition. We analyze the dynamics induced by local interaction rules using algebraic graph theory and methods inspired by the statistical physics of spin-glass materials. We describe and explain the phase transition phenomena that we have found in these evolutions. We model the interactions among agents as cooperative games and show that trust can encourage agents to collaborate. We also describe a model for trust evaluation that uses pairwise iterated graph games between the agents to create a 'trust reputation' with evolution coupled to the game dynamics. Finally, we present a new modeling framework for trust metric evaluation as linear iterations over ordered semirings, by treating such evaluations as path problems in MANET. This allows us to formulate problems of resilience of trust metrics and trust evaluation to attacks.
Reception to follow in the second floor atrium, Siebel Center.
John S. Baras is the Lockheed Martin Chair in Systems Engineering in the Electrical and Computer Engineering Department, the Computer Science Department, and the Institute for Systems Research at the University of Maryland College Park. He received the B.S. in Electrical Eng. from the Nat. Techn. Univ. of Athens, Greece in 1970, and the M.S. and Ph.D. in Applied Math. from Harvard Univ. in 1971 and 1973.
He was the founding Director of the Institute for Systems Research (one of the first six NSF Engineering Research Centers) from 1985 to 1991. Since August 1973 he has been with the Electrical and Computer Engineering Department and the Applied Mathematics Faculty at the University of Maryland, College Park, where he is currently a Professor holding a permanent joint appointment with the ISR. In February 1990 he was appointed to the Lockheed Martin Chair in Systems Engineering. Since 1991 Dr. Baras has been the Director of the Maryland Center for Hybrid Networks (HYNET) (a NASA Research Partnership Center).
Among his awards are the 1980 Outstanding Paper Award of the IEEE Control Systems Society; 1978, 1983, and 1993 Alan Berman Research Publication Awards from NRL; 1991 and 1994 Outstanding Invention of the Year Awards from the University of Maryland; in 1998 the Mancur Olson Research Achievement Award, from the Univ. of Maryland College Park (award recognizes faculty whose research achievements have been extraordinary); 2002 Best Paper Award at the 23rd Army Science Conference, Orlando, Florida; and Best Paper Award at the 2004 Wireless Security conference. Dr. Baras is a Fellow of the IEEE.
His research interests include control, communication, and computing systems. He was the initial principal architect of the ISR M.S. program in Systems Engineering. More recently, he has been heavily involved in the development of new core courses for systems engineering. His efforts address the often-emphasized need for a new integrative approach to engineering (holistic rather than in parts), which in turn addresses the needs for modular design, systems thinking, and teamwork.
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