ادغام امن اطلاعات در شبکه های حسگر بی سیم Secured data aggregation in wireless sensor networks

1. Introduction A wireless sensor network (WSN) is deployed in an open and sensitive environment like health monitoring, military surveillance, industrial monitoring, landslide detection and so on. It consists mainly of two types of nodes: sensor nodes and sink nodes. The sensor nodes are similar to that of a small computer, but they have limited processing capability, memory and battery power. Due to the resource constraint nature of sensor nodes, the direct transmission of raw data from the sensor nodes to the sink nodes consumes more energy and leads to a lot of congestion in the network. To reduce energy consumption, data aggregation is introduced in a WSN, as shown in Figure 1. More powerful sensor nodes act like aggregators (cluster head) or, in some cases, regular nodes act as aggregators (Castelluccia et al., 2009). These aggregators collect and process the data coming from the other sensor nodes of the network. For example, the aggregation functions like sum, min and max are useful in calculating temperature readings. The aggregator collects the data from n sensor nodes, calculates the sum of all n values and forwards it to the sink node. The sink node, after receiving the sum value, calculates the average temperature by dividing the value by n. The data aggregation saves the energy of sensor nodes and, thereby, increases the lifetime of the network (Papadopouloset al., 2012). Security of data aggregation is a challenging task in WSNs. False aggregation may lead to a large damage in the sensor network. For example, in the case of health-related applications, the attacks on sensor nodes may affect the person’s life, and in the case of military applications, it may lead to a national security threat. Various attacks like node compromise attack, eavesdropping, collision attack, Sybil attack, blackhole attack, sinkhole attack, selective message forwarding and attacks on data aggregation occur. (Xing et al., 2005). So, the secure data aggregation needs the following key properties: confidentiality, integrity, authentication and freshness of data (Papadopouloset al., 2012). The objective of the present study on Secured Data Aggregation (SDA) in WSNs is to securely transmit the aggregated data to the base station by reducing the energy consumption of sensor networks. The Paillier additive homomorphic cryptosystem is used to encrypt the data, and Boneh et al.’s aggregate signature method is used to generate the signature at each sensor node (Boneh et al., 2003).