A survey of security issues in wireless sensor networks <s> Protocol operations <s> Secure data transmission and data aggregation are critical in designing cluster-based sensor networks. This paper presents an Energy-efficient and Secure Pattern-based Data Aggregation protocol (ESPDA) for wireless sensor networks. ESPDA is energy and bandwidth efficient because cluster-heads prevent the transmission of redundant data from sensor nodes. ESPDA is also secure because it does not require the encrypted data to be decrypted by cluster-heads to perform data aggregation. In ESPDA, cluster-head first requests sensor nodes to send the corresponding pattern code for the sensed data. If multiple sensor nodes send the same pattern code to the cluster-head, then only one of them is permitted to send the data to the cluster-head. Hence, ESPDA has advantages over the conventional data aggregation techniques with respect to energy, bandwidth efficiency and security. Simulations results show that as data redundancy increases, the amount of data transmitted from sensor nodes to cluster-head decreases up to 45% when compared to conventional algorithms. <s> BIB001 </s> A survey of security issues in wireless sensor networks <s> Protocol operations <s> Wireless sensor networks consist of many inexpensive wireless nodes, each having sensing capability with some computational and communication power. Asymmetric cryptographic algorithms are not suitable for providing security on wireless sensor networks due to limited computation, power, and storage resources available on sensor nodes. Therefore, the energy-efficient security protocol proposed in this paper uses symmetric cryptographic algorithms to support security. To mitigate the drawbacks of symmetric cryptographic algorithms, the session key is changed dynamically, in addition to employing code-hopping technique in non-blocking OVSF codes. <s> BIB002 </s> A survey of security issues in wireless sensor networks <s> Protocol operations <s> In wireless sensor networks, sensor nodes are spread randomly over the coverage area to collect information of interest. Data fusion is used to process these collected information before they are sent to the base station, the observer of the sensor network. We study the security of the data fusion process in this work. In particular, we propose a witness-based solution to assure the validation of the data sent from data fusion nodes to the base station. We also present the theoretical analysis for the overhead associated with the mechanism, which indicates that even in an extremely harsh environment the overhead is low for the proposed mechanism. <s> BIB003 </s> A survey of security issues in wireless sensor networks <s> Protocol operations <s> Sensor networks are often deployed in unattended environments, thus leaving these networks vulnerable to false data injection attacks in which an adversary injects false data into the network with the goal of deceiving the base station or depleting the resources of the relaying nodes. Standard authentication mechanisms cannot prevent this attack if the adversary has compromised one or a small number of sensor nodes. In this paper, we present an interleaved hop-by-hop authentication scheme that guarantees that the base station will detect any injected false data packets when no more than a certain number t nodes are compromised. Further, our scheme provides an upper bound B for the number of hops that a false data packet could be forwarded before it is detected and dropped, given that there are up to t colluding compromised nodes. We show that in the worst case B is O(t/sup 2/). Through performance analysis, we show that our scheme is efficient with respect to the security it provides, and it also allows a tradeoff between security and performance. <s> BIB004
Cipher-based aggregation upstream stage requires that a pairwise key be shared between an aggregator and its sensor nodes. Çam et al. proposed an energy-efficient secure patternbased data aggregation (ESPDA) protocol for wireless sensor networks in BIB001 BIB002 . ESPDA is applicable for hierarchy-based sensor networks. In ESPDA, a cluster head first requests sensor nodes to send the corresponding pattern code for the sensed data. If multiple sensor nodes send the same pattern code to the cluster head, only one of them is permitted to send the data to the cluster head. ESPDA is secure because it does not require encrypted data to be decrypted by clusterheads in order to perform data aggregation. Further, the authors introduced a secure differential data aggregation (SDDA) scheme based on pattern codes  . SDDA prevents redundant data transmission from sensor nodes by implementing the following schemes: SDDA transmits differential data rather than raw data, SDDA performs data aggregation on pattern codes representing the main characteristics of sensed data, and SDDA employs a sleep protocol to coordinate the activation of sensing units in such a way that only one of the sensor nodes capable of sensing the data is activated at a given time. In the SDDA data transmission scheme, the raw data from sensor nodes is compared to reference data with the difference data being transmitted. The reference data is obtained by taking the average of previously transmitted data. Du et al. proposed a witness-based data aggregation (WDA) scheme for WSNs to assure the validation of the data sent from data fusion nodes to the base station BIB003 . In order to prove the validity of the fusion result, the fusion node has to provide proofs from several witnesses. A witness is one who also conducts data fusion like a data fusion node, but does not forward its result to the base station. Instead, each witness computes the message authentication code (MAC) of the result and then provides it to the data fusion node who must forward the proofs to the base station. Wagner studied secure data aggregation in sensor networks and proposed a mathematical framework for formally evaluating their security  . In BIB004  , the authors proposed two data fusion schemes for the filtering of injected false data in sensor networks, which will be introduced below.