Sécurité du réseau

Résumé

La sécurité du réseau comprend les politiques et les pratiques adoptées pour empêcher et surveiller l'accès non autorisé, l'utilisation abusive, la modification ou le refus d'un réseau informatique et des ressources accessibles sur le réseau. Références Catégorie:Sécurité du réseau informatique

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The Byzantine failure model allows arbitrary behavior of a certain fraction of network nodes in a distributed system. It was introduced to model and analyse the effects of very severe hardware faults in aircraft control systems. Lately, the Byzantine failure model has been used in the area of network security where Byzantine-tolerance is equated with resilience against malicious attackers. We discuss two reasons why one should be careful in doing so. Firstly, Byzantine-tolerance is not concerned with secrecy and so special means have to be employed if secrecy is a desired system property. Secondly, in contrast to the domain of hardware faults, in a security setting it is difficult to compute the assumption coverage of the Byzantine failure model, i.e., the probability that the failure assumption holds in practice. For this latter point we develop a methodology which allows to estimate the reliability of a Byzantine-tolerant solution exposed to attackers of different strengths.

2003

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Within the realm of network security, we interpret the concept of trust as a relation among entities that participate in various protocols. Trust relations are based on evidence created by the previous interactions of entities within a protocol. In this work, we are focusing on the evaluation of trust evidence in ad hoc networks. Because of the dynamic nature of ad hoc networks, trust evidence may be uncertain and incomplete. Also, no preestablished infrastructure can be assumed. The evaluation process is modeled as a path problem on a directed graph, where nodes represent entities, and edges represent trust relations. We give intuitive requirements and discuss design issues for any trust evaluation algorithm. Using the theory of semirings, we show how two nodes can establish an indirect trust relation without previous direct interaction. We show that our semiring framework is flexible enough to express other trust models, most notably PGP's Web of Trust. Our scheme is shown to be robust in the presence of attackers.

2006

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Trust Evaluation in Ad-Hoc Networks

Georgios Theodorakopoulos

An important concept in network security is trust, interpreted as a relation among entities that participate in various protocols. Trust relations are based on evidence related to the previous interactions of entities within a protocol. In this work, we are focusing on the evaluation process of trust evidence in Ad Hoc Networks. Because of the dynamic nature of Ad Hoc Networks, trust evidence may be uncertain and incomplete. Also, no pre-established infrastructure can be assumed. The process is formulated as a path problem on a directed graph, where nodes represent entities, and edges represent trust relations. Using the theory of semirings, we show how two nodes can establish an indirect trust relation without previous direct interaction. The results are robust in the presence of attackers. We give intuitive requirements for any trust evaluation algorithm. The performance of the scheme is evaluated on three topologies.

ACM Press2004

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