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Modeling Secure Connectivity of Self-Organized Wireless Ad Hoc Networks. Chi Zhang, Yang Song and Yuguang Fang IEEE INFOCOM 2008. Computer Architecture Lab. Hanbit Kim 2008. 12. 4. Contents. Introduction Problem & Answer Network Model Problem Formulation Properties of Secure Graph
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Modeling Secure Connectivity of Self-Organized Wireless Ad Hoc Networks • Chi Zhang, Yang Song and Yuguang Fang • IEEE INFOCOM 2008 Computer Architecture Lab. Hanbit Kim 2008. 12. 4
Contents • Introduction • Problem & Answer • Network Model • Problem Formulation • Properties of Secure Graph • Conclusion • Discussion
Introduction • Wireless Ad Hoc Networks (WANET) • Wireless networks without the support of centralized network management
Introduction • Security architecture with self-organization • Users prefer to join and leave the network at random. • Without the trusted third party • How to exploit primary security associations (SA) for secure connectivity
Question & Answer • Question • What is the minimum fraction of primary SAs for securing all the links? • Answer • When the average number of authenticated neighbors of each node is Θ(1)
Network Model Physical Graph G(Χn, Εpl) Trust Graph G(Χn, ΕSA) Local Augmented Secure Graph G(Χn, Ε’sl) Isolated node Cluster Secure Graph G(Χn, Εsl) Cluster
Network Model • r • Communication range • Pf • Probability that two nodes which meet as neighbors will be friends • k • Pf • nπr2 • Expected value of the number of neighboring friends
Assumptions • Nodes are distributed uniformly at random. • SAs are always symmetric. • Physical Graph G(Χn, Εpl) is connected. • Trust Graph G(Χn, ΕSA) is connected.
Problem Formulation • Constructing a secure path between an arbitrary pair of nodes • What should k be? • We must avoid routing-security dependency loop.
Properties of Secure Graph • Theorem 1: • For secure graph G(Χn, Εsl), there is a critical threshold kc = log(n). • If k > kcthen G(Χn, Εsl) is connected.
Properties of Secure Graph • Theorem 2: • For secure graph G(Χn, Εsl), there is a percolation threshold kp . • Approximately, kp • If k > kpthen there is only one infinite-order cluster.
Properties of Secure Graph • Connected Phase • k > kc • The secure graph G(Χn, Εsl) is connected. • There is only one cluster.
Properties of Secure Graph • Supercritical Phase • kp < k <= kc • The secure graph G(Χn, Εsl) consist of one infinite-order cluster and isolated nodes. • Handling isolated nodes
Properties of Secure Graph • Subcritical phase • k < kp = 4.5 • The network consists of small clusters. • The network cannot achieve secure connectivity.
Conclusion • The secure graph is at least in the supercritical phase. • Achieve secure connectivity when the average number of authenticated neighbors is at least Ω(1).
Discussion • Not uniform distribution • Not connected trust graph