برقراري يك مدل اعتماد توزيع شده مقاوم جهت بكارگيري در شبكه هاي اقتضايي متحرك

چكيده انگليسي :

Robust and distributed trust model for mobile ad hoc networks Sadeq Bonari b sadeq@ec iut ac ir Date of Submission 2012 12 25 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Mehdi Berenjkoub and Mohammad Dakhilalian brnjkb mdalian @cc iut ac ir Abstract A mobile ad hoc network MANET is a self organizing network comprised of mobile nodes that communicate with each other via wireless links without any fixed infrastructure Securing the exchanges in such network is required to guarantee a widespread development of services for this kind of networks Inherent vulnerability of mobile ad hoc networks introduces new security problems which are generally more prone to physical security threats The possibility of eavesdropping spoofing denial of service and impersonation attacks increases Similar to xed networks security of mobile ad hoc networks is considered from different points such as availability con dentiality integrity authentication non repudiation and access control However security approaches used to protect the xed networks are not applicable due to the salient characteristics of mobile ad hoc networks such as weak secure wireless links unpredictable and freely movement of mobile devices and dynamic topology of network The deployment of any security service requires the de nition of a trust model that de nes who trusts who and how In wired networks such as Internet a centralized trusted third party TTP is responsible for determine security policies However centralized TTP can cause some problems such as single point of failure and some limitations for accessibility Therefore it is proposed use of distributed TTP The threshold cryptography is a good solution to the problem of deployment a TTP in MANET In a distributed TTP the functionality of TTP is distributed between some special nodes using a threshold secret sharing scheme In threshold secret sharing schemes a secret is distributed to multiple nodes in a manner that the secret is disclosed only if a threshold number of shareholders are compromised Secret sharing alone does not defend against mobile adversaries which attack compromise and control one server for a limited period before moving to another The defense here is proactive secret sharing whereby servers periodically create a new independent secret sharing and then replace old shares with new ones In this thesis at first we indicate a specific attack to the pervasive proactive secret sharing scheme proposed by Herzberg in 1995 and show that this scheme and its successors are inapplicable for using in MANETs Then a secure and scalable proactive secret sharing scheme is presented to eliminate the weaknesses of Herzberg scheme In comparison to Herzberg scheme and its successors in the proposed scheme server nodes in every subset comprised of threshold number of server nodes can refresh their shares independently Moreover in the proposed proactive secret sharing scheme server nodes can verify the correctness of received shares without requirement to broadcasting witnesses It leads to lower communication and computation overhead no need to knowledge of global network topology and compatibility with dynamic network topology Therefore our proposed proactive secret sharing scheme will be scalable and efficient Then a robust and distributed trust model for mobile ad hoc networks is proposed in which the proposed proactive secret sharing is used to defend against mobile adversary Keywords Mobile ad hoc networks Distributed trust model Distributed certificate authority Threshold cryptography Proactive secret sharing

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برقراري يك مدل اعتماد توزيع شده مقاوم جهت بكارگيري در شبكه هاي اقتضايي متحرك

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