Date of Publication :16th October 2017

Abstract: A wireless Sensor Network (WSN) is a distributed network of small sensor nodes deployed in large numbers to monitor the environment or other systems by the measurement of physical parameters such as temperature, pressure, or relative humidity. These nodes by monitoring collect detailed information about the physical environment in which they are installed, and then transmit the collected data to the Base Station (BS). BS is a gateway from sensor networks to the outside world. It passes the data it receives from sensor nodes to the server from where end-user can access them. Security in WSN is a greater challenge due to the processing limitations of sensor nodes and nature of wireless links. Extensive use of WSNs is giving rise to different types of threats. To defend against the threats proper security schemes are required. Traditionally security is implemented through hardware or software and is generally achieved through cryptographic methods. Limited area, nature of links, limited processing, power and memory of WSNs leads to strict constraints on the selection of cryptographic techniques. The Sybil attack is one of the dangerous attacks against sensor and ad-hoc networks, where a node illegitimately claims multiple identities. A Sybil attacker can cause damage to the ad hoc networks in several ways. For example, a Sybil attacker can disrupt location-based or multipath routing by participating in the routing, giving the false impression of being distinct nodes on different locations or paths. In wireless sensor networks, a Sybil attacker can change the whole aggregated reading outcome by contributing many times as a different node. In voting-based schemes, a Sybil attacker can control the result by rigging the polling process using multiple virtual identities. In vehicular ad hoc networks, Sybil attackers can create an arbitrary number of virtual nonexistent vehicles and transmit false information in the network to give a fake impression of traffic congestion in order to divert traffic.

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