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Abstract
Wireless sensor networks (WSNs) are vulnerable to several types of attacks including passive eavesdropping, jamming, compromising (capturing and reprogramming) of the sensor nodes and insertion of malicious nodes into the network. Widespread adoption of WSNs, particularity for mission-critical tasks, hinges on the development of strong protection mechanisms against such attacks. Due to the scarcity of resources, traditional wireless network security solutions are not viable for WSNs. The life span of a sensor node is usually determined by its energy supply which is mostly expended for data processing and communication. Therefore, security solutions which demand excessive processing, storage or communication overhead are not practical. In particular, due to their high computational complexity, public key ciphers are not suitable for WSNs. An important application of WSNs, involves decentralized detection whereby the sensors send their measurements to an ally fusion center (AFC) which attempts to detect the state of nature using the data received from all the sensors .Due to the broadcast nature of the wireless media, the sensors data are prone to interception by unauthorized parties . Considering the problem of secure detection in wireless sensor networks operating over insecure links. It is assumed that an eavesdropping fusion center (EFC) attempts to intercept the transmissions of the sensors and to detect the state of nature. The sensor nodes quantize their observations using a multilevel quantizer. Before transmission to the ally fusion center (AFC), the sensor nodes encrypt their data using a probabilistic encryption scheme, which randomly maps the sensor’s data to another quantizer output level using a stochastic cipher matrix. The communication between the sensors and each fusion center is assumed to be over a parallel access channel with identical and independent branches and with each branch being a discrete memory less channel. Employ J-divergence as the performance criterion for both the AFC and EFC. The optimal solution for the cipher matrices is obtained in order to maximize J-divergence for AFC, whereas ensuring that it is zero for the EFC. With the proposed method, as long as the EFC is not aware of the specific cipher matrix employed by each sensor, its detection performance will be very poor. The cost of this method is a small degradation in the detection performance of the AFC. The proposed scheme has no communication overhead and minimal processing requirements making it suitable for sensors with limited resources. Numerical results showing the detection performance of the AFC and EFC verify the efficacy of the proposed method.