CLUSMA-A Mobile Agent based clustering middleware for Wireless Sensor Networks

CLUSMA: A Mobile Agent based clustering middleware forWireless Sensor NetworksUsman Sharif1, Abid Khan1, Mansoor Ahmed1, Waqas Anwar2, Ali Nawaz Khan3,1Department of Computer ScienceCOMSATS Institute of Information Technology, Islamabad, Pakistanitseen@{abidkhan,mansoor}@.pk2 Department of Computer ScienceCOMSATS Institute of Information Technology, Abbottabad, Pakistanwaqas@.pk3 Department of Electrical Engineering, COMSATS Institute of Information Technology, Lahore, Pakistanankhan@.pkABSTRACTThis paper proposes CLUSMA: a middleware framework for communication between sensor nodes in Wireless sensor network. Our proposed technique is based on clustering technique (CLUS) and it uses Mobile Agent (MA).This paper gives a sketch of the middleware and the actual implementation of the framework are in progress. The main objective of this middleware is to utilize the networks functions and resources in an effective way. Because the proposed framework is based on MA it will work in homogenous as well as heterogeneous environment. Previous such frameworks used symmetric secret key for sensor nodes authentication. The proposed framework will provide security in heterogeneous environment by using mobile agents in a cluster which will communicate with agents in other cluster.KeywordsMiddleware, clustering algorithm, mobile agents, Program Integrity Verification (PIV), symmetric secret key, heterogeneous environment1.INTRODUCTIONWireless Sensor Networks (WSN) is becoming important for many emerging applications such as military surveillance, alerts on terrorists and burglars. The security of sensor networks is of utmost importance [1]. Due to resource constraints on sensor nodes, it is not feasible for sensors to use traditional pair-wise key establishment techniques such as public key cryptography and key distribution centre [2].To protect the sensors from physical tampering and manipulation of the sensor programs, [16] proposed a soft tamper-proofing scheme that verifies the integrity of the program in each sensor device, called the program integrity verification (PIV). In PIV protocol the sensors rely on PIV servers (PIVSs) to verify the integrity of the sensor programs. The sensors authenticate PIVSs with centralized and trusted third-party entities, such as authentication servers (ASs), in the network. Distributed authentication protocol of PIVSs (DAPP) DAPP is a solution to the problem of authenticating PIVSs in a fully distributed manner without the ASs. This paper is organized as following, section II talks about the related work, section III describes design of proposed middleware framework with clustering technique, PIV implementation over middleware framework is included in IV section and last section concludes the paper.2.RELATED WORKA security model for low-value transactions, especially focusing on authentication in ad hoc networks is presented in [3]. They used the recommendation protocol from the distributed trust model [4] to build trust relationships and extend it by requesting for references in ad hoc networks. Each node maintains a local repository of trustworthy nodes in the network, and a path between any two nodes can be built by indirectly using the repositories of other nodes. They also introduced the idea of threshold cryptography [5] in which, as long as the number of compromised nodes is below a given threshold, the compromised nodes cannot harm the network operation. Some threats and possible solutions for basic mechanisms and security mechanisms in mobile ad hoc networks are presented in [6]. They developed a self-organizing public-key infrastructure. In their system, certificates are stored in local certificate repositories and distributed by the users. In contrast, our work focuses on authentication of servers, while their work features admission control and pair wise key establishment.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.FIT’09, December 16–18, 2009, CIIT, Abbottabad, Pakistan.Copyright 2009 ACM 978-1-60558-642-7/09/12 (10)3.Design principle for WSN MiddlewareThe software design for WSNs should follow several basic principles. We re-interpret those principles for the design of middleware as follows: The middleware should provide Data-centric mechanisms for data processing and querying within the network. Due to its simplicity, flexibility, and robustness, cluster-based network architecture has been widely used in the design and implementation of network protocols and collaborative signal processing applications for WSNs, such as [8-10]. Intuitively, cluster-based architecture is suitable for hosting the data-centric processing paradigm from both geographical and system design perspectives [9,10]. While designing any middleware for WSN the followings aspects must be addressed properly (1) Heterogeneity (2) Localized Algorithms (3) Energy and Resource management (4) Data Aggregation (5) Encoding and Compression (6) Scalability (7) Security3.1HeterogeneityLike in regular distributed systems, heterogeneity is a phenomenon also seen in WSN, which should be managed by the middleware. Sensor nodes can be heterogeneous by construction, that is, some nodes have larger batteries, farther-reaching communication devices, or more processing power. Middleware should have the knowledge about the nodes’ states, dispatching tasks based on its knowledge concerning their remaining energy, their communication devices, and their computational resources.3.2Localized AlgorithmsSince the cluster-based architecture localizes the interaction of sensor nodes and hence the coordination and control overhead within a restricted vicinity, it is reasonable to regard each cluster as a basic function unit of the middleware. Both principles data-centric and localized algorithms strongly motivate cluster-based architectures. In fact, such architectures have been widely investigated in ad hoc networks since they “promote more efficient use of resources in controlling large dynamic networks”[11]. Compared with mobile networks that incur a high cost for maintaining clusters throughout the network, WSNs usually consist of stationary sensor nodes with less dynamics. Hence, the cost for superimposing cluster architecture over the physical network is affordable, given the potential advantages offered by clusters in designing scalable and localized data centric algorithms. [12]3.3Energy and resource managementRecent researches in microelectronics have made it possible to produce very tiny sensor devices, sometimes on the order of one cubic cm. Due to their small size, sensor nodes suffer from limited resources like energy, computing power, memory, and communication bandwidth. Therefore, the middleware on top of those devices should be lightweight, energy efficient, smartly managing restrained resources in order to provide the required services while maximizing the device’s life. Most of the time, it is nearly impossible to recharge these sensory devices, because of their huge number, their small size, and because they are scattered in the field so it is hard also to find all of them. 3.4Data AggregationWhen organizing a network in a distributed fashion, the nodes in the network are not only passing data or executing applications programs, they are also actively involved in taking decisions about how to operate the network. This is a specific form of information processing that happens in the network, but is limited to information about the network itself. When the concrete data transported by the network is also taken into account into this information processing, that’s in-network processing. In-network processing has different forms: data aggregation and data encoding and compression. Perhaps one of the most used techniques of in-network processing is data aggregation [13], also called data fusion. The benefit of this technique -mainly power saving- comes from the fact that transmitting data is considerably more expensive than even complex computations. This form of in-network processing is called aggregation since data collected from different nodes along the way between the source and the sink is aggregated into a condensed form while satisfying some conditions for the result to be meaningful.3.5Encoding and CompressionSince sensor nodes are deployed in physical environments, the readings of the adjacent ones are going to be very similar, they are correlated. The compression and encoding techniques exploit such correlation, which can be a spatial one (in adjacent nodes) or a temporal one (readings at the same moment). Middleware should provide data aggregation and data compression algorithms, giving the applications above the ability to choose the algorithm that best suits.3.6ScalabilityMiddleware should support scalability by maintaining acceptable levels of performance as the network grows. Some network architectures have been investigated and proven suitable for growing networks such as clustered networks [13], and data-centric models. Moreover, scalability provides robustness and fault tolerance for the network.3.7SecurityIt obvious that security measures in WSN shouldn’t be considered in the same way as other kinds of networks for many reasons: WSN infrastructure is made of small, cheap nodes scattered in a potentially hostile area, therefore it’s impossible to prevent the sensor nodes to be physically accessed by attackers. In that case, an attacker could achieve full control over the captured node, so he can reads its memory or alter its software. Some cryptographic algorithms are hard to implement because of the memory and computational constraints. When performing in-network processing, several nodes access the data to change it, and therefore there are a large number of parties involved in end-to-end information transfers. The limited energy of a node is particularly attracting for attackers, they can force it to exhaust its energy and die.4.Middleware Framework with clustering technique using mobile agent (CLUSMA)We are designing a unified framework for WSN that contains predefined parameters regarding efficient utilization of network resources, to reduce the communication overhead, to remove the bottleneck of authentication server. The designing of this framework is better approach to introduce integrity between sensor nodes and between sensors and servers in a more effective way. Security constraints that effect networks resources so badly can be controlled in more effective way by implementing this framework. We intend to implement program integrity verification (PIV) protocol in our middleware.4.1Pre-defined parametersAs mentioned earlier that the framework works with its predefined parameters. First of all, the number of sensor nodes is decided that will remain part of the pre-defined network with predefined area covered by that nodes. Their transmission coverage or range will also be pre-assigned. With that pre-assigned range all the nodes will perform their functions of sensing and communication. There will be lot of areas with so many sensor nodes exist in their own network and will perform their functions in their specific pre-assigned area.4.2Interconnection between sensorsEvery sensor node can communicate to a sensor node in the same network directly or indirectly but what will happen if one sensor of a network wants to communicate with any other sensor of some other networks? There are a number of solutions to this kind of problems in wireless networks like Ad hoc networks. Mobile agent is one of possible solutions. It will reside one a node with bit high processing and transmission power, belong to a network and can communicate to the mobile agent of another network because of its high transmission power. Mobile agent middleware introduces extensibility of the network functions, e.g. bandwidth, frequency. Mobile agent middleware’s communication with each other in different clusters where the cell’s frequency reuse implementation facilitate WSN environment in more effective way.4.3ClusteringA cluster consists of number of nodes. As in our proposed idea, the sensors will be scattered into clusters on some pre-defined basis. All the sensors belong to a cluster can communicate with every node in a cluster. Same, every node in cluster can communicate to the nodes of different clusters through middleware or agent (As shown in the figure) that have high processing than normal sensor nodes but these agents cannot perform very crucial functions like maintaining data of every node or the complex computations related to key generation and distribution.Inter-Cluster Coordination: In the proposed middleware, information exchange between clusters is necessary for both information sharing and coordination. For instance, data gathered at one cluster can be requested by either the base station or other clusters across the network. [14]. This tradeoff of energy against application fidelity is also important for inter-cluster routing. For instance, an energy efficient packet scheduling scheme over an existing data gathering substrate is described in [15]. Similar techniques can be applied for information dissemination among clusters.Middleware or AgentSensor nodeFig.1. CLUSMA MiddlewareIntra-Cluster coordination: Another issue arises when multiple clusters overlap with each other. For instance, two separated objects initially tracked by two different clusters may move across or eventually move together, which leads to the overlap of the two clusters. In such a case, multiple clusters may compete for resources. It is therefore important to establish necessary mechanisms for detecting the existence of overlapped clusters and coordinating between clusters to avoid unfairness, starvation or deadlock during resource competition. It is sometimes helpful to perform cluster combination if two clusters overlap on a large portion of geographical area and will co-exist for a long time period. Cluster combination can be used to achieve reduced coordination overhead and increased resource utilization, while necessitating high scalability of the cluster control protocol and resource management algorithms. The counterpart of cluster combination is cluster splitting. Cluster splitting is needed when two close objects tracked by a single cluster begin to move toward opposite directions. However, cluster splitting can also be regarded as the procedure of reducing the application load on the original cluster that tracks one object and forming another cluster for tracking the other object.5.PIVS OVER CLUSMAPIV program is installed on every node. Within a cluster, every PIV Senor node will communicate to other PIV node, the integrity of the nodes can be achieved in this way. PIV protocols are there in between these communication entities. The same PIV is installed on all PIVSs servers that communicate with their nodes in clusters. PIVSs will be performing all critical operations related to key generation and distributions, maintaining data and information of every node in a cluster etc in order to achieve more reliability, and these PIVSs will be replicated. As discussedearlier, if a sensor node of a cluster wants to communicate with some other node of another cluster, then node will first contact to its PIVS, PIVS inform that node about the destination node with its exact location and clusters. One of the important aspect of PIVs is that it will be replicated on inter and intra cluster basis. PIVs information will be distributed on all the clusters. After knowing the information about the destination node, source node contacts to its mobile agent middleware that will communicate to the mobile agent having destination sensor node. Integrity and authentication of the nodes within a cluster or outside the cluster are major challenges to be tackled down. We are of the view that this middleware framework performs well to overcome these security issues. The information about all the nodes of all the clusters is distributed on the PIVSs. The verification of the nodes can be achieved simply by the verification procedure that takes place in the initiation of communication of one node to another. Every node contains pre-loaded key generation material [17], on the basis of that code; symmetric key is generated that is pairwise key sharing between sensor nodes. In [17] key server randomly generated a symmetric bivariate k-degree polynomial f(x,y) that is a secret known only to the key server. Any two nodes in the network generate a pairwise key by substituting x and y by their nodes IDs. Authentication of the middleware mobile agents is also an issue that is solved in our proposed framework. There should be key sharing process between mobile agents. They will authenticate each other on the basis of secret keys that will be shared by PIVSs. PIVSs will hold key generation function to be used to generate pair wise key.6.CONCLUSIONThe proposed middleware framework incorporates clustering techniques to reduce the amount of communication between sensor nodes. We know that sensors are usually deployed in hostile and unattended environments and hence are susceptible to various attacks, including node capture, physical tampering, and manipulation of the sensor program. CLUSMA framework will be able to provide security in the homogeneous and heterogeneous WSN environment by using one or more middleware mobile agents in a cluster. Authentication of the middleware mobile agents is also an issue that is solved in our proposed framework. There should be a key sharing process between mobile agents so that they can authenticate each other on the basis of secret keys. PIVSs will hold key generation function, on the basis of that function pairwise key will be generated.7.REFERENCES[1]S. A. Camtepe and B. 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