Energy Efficient Secured Leach Protocol for WSN
Rashim Rana Er. Anoopa Arya(Pursuing M. Tech, CSE) (Assistant Professor, CSE)
Maharishi Ved Vyas Engineering College Kurukshetra University, Kurukshetra, India
Abstract- The aim of this Paper is to reduce the energy consumption while providing security.The encryption scheme that perform operation on the cipher text is most important for the WSN and for LEACH protocol also. In LEACH amount of energy is very less and it is a limitation of LEACH. The designing of confidentiality scheme in WSN is important so that data can be transmitted to receiver efficiently and securely and at the same time consume minimum amount of energy. For this purpose we proposed LEACH_HE_MH in this min- heap for load balancing and homomorphic encryption for confidentiality is added to LEEACH protocol. In this min-heap is used for finding the energy efficiency and as well as better cluster head management and in homomorphic encryption data can be aggregated mathematically without decryption so energy consumption is reduce. Simulation results are obtained in terms of four metrics- amount of data transmitted throughput total energy consumed and number of nodes alive. It is observed that the performance of LEACH_HE_MH is somewhat better to LEACH.
Keywords: Wireless sensor network, base station, Low-Energy Adaptive Clustering Hierarchy, Cluster head, Homomorphic Encryption, Min –heap, Time division multiple access.
The Wireless Sensor Network (WSN) is a distributed network which is made up of small, lightweight wireless nodes. WSNs consist of inexpensive, small, battery powered sensing devices which are fitted with wireless transmitters and spatially scattered in nature. Sensors have the ability to communicate through wireless channels, and their memory, energy, computational power and are constrained . The WSN illustration is shown in figure 1.
Fig 1 Basic Wireless Sensor Network 
WSN contains a large number of sensor nodes in an area which is targeted for performing surveillance tasks such as military surveillance, environmental, monitoring, animal tracking, agriculture, industry, and home applications. At present, it shows a great charm in target tracking, disaster salvage, security monitoring and other areas. These sensor nodes consist of communication, data sensing, and data processing units. WSN is a special kinds of clustered ad-hoc network that usually includes cluster heads, sensor nodes and sink nodes. Each sensor nodes collects data by sensing its surrounding region and transmit this data to other nodes hop by hop and after multi hop this data is reach will reach the sink (also called a base station)[3,6]. In WSN, operation of sensor nodes on limited batteries, which make the energy resources the major bottleneck.
WSN has many advantages, such as high precision monitoring, wide coverage, self-organization, fault tolerance and so on. The nodes are deployed in a hostile environment, so the energy consumption is high and it has limited battery life. If the battery is dead the node stop working so it is impossible for people to replace or charge the battery because it has high cost. However, the number of nodes in such network is considerably high and monitoring of these nodes is quite difficult, especially when the nodes are distributed in the regions far away from a city.
Fig 2: Architecture of Sensor Node 
16 node perform aggregation of data and reduce the consumption
of energy. The data is analyzed by the sink node for some specific event or action. Data is sensed by the network and the energy of the nodes is dissipated. Whenever the nodes receive some data, they send it further to other nodes or BS.
Designing of routing protocols for WSN is challenging task. These networks have various constraints such as limited bandwidth limited computing power and limited energy supply. The main designing aim of WSN is to carry out data communication and increasing the life time of network.
Routing protocol is an important factor which affecting the energy consumption of sensor nodes. There are three routing protocols of wireless sensor network
Flat Based Routing Protocol: In flat based routing the same role and functionality of transmitting and receiving the data is played by all the nodes. In this the selection of specific set of sensor nodes to be queried is very typical due to lack of global identification with random deployment of sensor nodes. The query is send to different part of the field by BS and wait for resulted data from only selected parts of field. This method is called data centric routing.
Hierarchical Routing Protocol: In this nodes are having different roles like cluster heads, members of clusters, etc. Hierarchical routing is a two layer architecture where one layer is for the assignment of cluster head selection and the other layer is for routing.
Location Based Routing Protocol: In this location of nodes play a main role. Sensor nodes are addressed by means of their locations. The distance between nodes can be estimated on the basis of incoming signal strengths. To save energy, some location-based schemes demand that nodes should go to sleep if there is no activity.
Hierarchical-based routing protocols are also called as cluster based routing protocols. In order to avoid redundancy hierarchical routing protocols are the best. Nodes are grouped into clusters in hierarchical routing protocol. Each cluster has a CH the election of which is based on different election algorithms. The CH are used for higher level communication, reducing the traffic overhead. In the routing hierarchy many advantages are present. It reduces the size of routing tables providing better scalability. To attain better performance the concept of hierarchical routing is utilized to perform energy-efficient routing in wireless sensor network. A variety of protocols have been discussed for prolonging the life of WSNs and routing the correct data to the base station. Some of the energy aware routing protocols are:- Low energy Adaptive Cluster Hierarchy routing protocol (LEACH), Power efficient gathering in sensor information system (PGASIS), Threshold sensitive energy efficient sensor network protocol (TEEN), Hierarchical power aware routing, Virtual Grid Architecture,
Base station controlled dynamic clustering protocol [4,8]
A. LEACH protocol:
LEACH (Low Energy Adaptive Clustering Hierarchy) is the most popular hierarchical cluster-based routing protocol which includes distributed cluster formation as shown in figure 3. The main idea in LEACH is to form clusters of the sensor nodes. These cluster are made based on received signal strength. In this a local cluster head is selected which communicate with the sink. In this protocol energy is saved because transmission is done by the CH rather than the all other nodes. For the reducing the inter cluster collisions LEACH uses a TDMA/ code division multiple access (CDMA) MAC.
Fig 3: LEACH protocol  The LEACH protocol operate on two phases:
• The Setup Phase: In this phase the clusters are organized in the network and CH are selected. In this CH change randomly over time for balancing the energy dissipation of nodes. Cluster head compress, accumulates and forward the data to the base station. This decision is made by the node choosing a random number between 0 and 1.If random number is less than a threshold value, T (n) for the current round the node will become cluster head.
Fig 4: Period of LEACH 
• The Steady state phase: In this phase sensor nodes start sensing and transmitting data to the CH. The CH node receive all the data from their nodes and aggregates it before sending it to the BS. For minimizing the overhead, the time period of the steady state phase is longer than the time period of the setup phase. Each node that is not a CH selects the closest CH and joins that cluster. After that the CH creates a schedule for each node in its cluster to transmit its data.
17 1. As LEACH use a Hierarchical Topology, so it is a
fundamental algorithm design. 2. Energy utilization is better 3. Life time of the system is better.
4. The algorithm provides prolonged network coverage (low latency).
1. Network simulator is necessary for the simulation
2. Fault-tolerance issues – when nodes fail or behave unexpectedly
3. In this paper we work in homogenous WSN and assumes all the nodes begin with same energy – this assumption may not be realistic 
B. Homomorphic Encryption
Homomorphic encryption is an encryption technique in which plain text is converted to cipher text by apply encryption. Aggregation on cipher text is done in the homomorphic encryption scheme. In HE the arithmetic operations are apply on the plain text like addition, multiplicative, subtractive etc. In this the function f is applu on the plain text for efficient computation of the cipher text. The function f is apply for confidential purpose of the data. We take one example of multiplicative HE in this decryption of the manipulation of two cipher text gives the multiplication of the two plain text. The encryption and decryption function are cumulative in nature. HE is useful when someone not having the decryption key so the person only needs to apply arithmetic operation on the cipher text. Full homomorphic encryption has many application like search on encrypted data, enables private queries to search engine etc. Fully homomorphic encryption improves the efficiency of secure multiparty computation
C. Min Heap
A min heap binary tree is an almost complete binary tree. In this keys and objects are stored at the nodes. The node with the smallest key value is called the root node and node’s key is greater than or equal to its parent’s. The name “heap” is chosen because it is described as a sort of objects with the smallest ones at the top. The maximum depth of the heap is O (log2n), so provided our If we provide our operations just move “up and down” the tree, should run in O (log n) time as required.
Fig. 5: Min-Heap Tree
At each round the rooted CH from the min-heap is picked the CH which has the minimum number of sensor nodes allotted to it and make this a CH. After making that node a CH assign sensor nodes to that CH. So that the load is distributed over minimum loaded CH in this way. The balancing of the load of the CHs is shown in the figure 2. Energy consumption and distance between two nodes are related to each other. At each round of the sensor node that sensor node which is nearest to the minimum loaded CH selected and assigned, thereby reducing the energy consumption of the sensor nodes. The min-heap algorithm considers both the issues, i.e., load balancing of the CHs and the energy efficiency of the sensor node .
A. S. Poornima et al (2010) In WSN large number of nodes are consist of with limited communication capabilities, sensing and computation. In such network resource constrained nodes are present and transmission of data in this is a energy-consuming operation. By reducing the number of bits transmitted on a network the lifetime of a network is increased. The data aggregation method is used for reducing the data transmission. The issues of security such as confidentiality, data integrity and freshness in data aggregation become essential when the WSN is deployed in a remote or hostile environment where sensors are prone to node failures. For achievement of security in data aggregation we use secure data aggregation schemes. In this paper the author propose a Secure Data Aggregation scheme which provides end-to-end data privacy. In this 30%-50% of the average number of bits transmitted are reduced .
18 Alisha Gupta et al (2013) Encryption schemes which are
operated over cipher text are of extreme importance for WSN & especially in LEACH protocol. Energy is the salient limit of LEACH. Due to this limitation, the designing of a confidentiality scheme for WSN is important by doing this the sensing data can be transmitted to the receiver efficiently and securely and at the same time energy consumed must be minimum. Hence the author proposed LEACH-HE in which homomorphic encryption is added to LEACH protocol. The homomorphic encryption is the confidentiality scheme in LEACH-HE. In this encryption technique algebraically aggregation of data is occur. The decryption of data is not occure hence energy consumption is less. In this proposed work results are obtained in terms of three forms - amount of data transmitted, total energy consumed and number of nodes alive. The performance of LEACH_HE is somewhat similar to LEACH .
Muneer Alshowkan et al (2013) Working with WSN is a challenging task because in this many challenges are present such as the limited resource in processing power, energy and storage. The security maintenance in WSN is a challenging task due to presence of limited energy. The aim of the paper is reducing the power consumption and improving the current security mechanisms in WSN. The energy routing protocol is provided by LEACH and it do not cover the security requirements. Alternatively, this paper aims to design LS-LEACH (Lightweight Secure LS-LEACH) which is more secure and energy efficient routing protocol. Authentication algorithm is added to this for assuring availability, authenticity and data integrity. Furthermore, this paper shows the improvement over LEACH protocol which make it more secure and tell how the energy efficiency is increased .
A. Babu Karuppiah et al (2013) Clustering is used for load balancing in WSN. The efficient technique for improving the lifetime and scalability of WSN is clustering algorithm. In this paper the author proposed a technique which is used for finding the energy efficiency and load balancing. In this paper min heap based clustering algorithm is used. In this the Efficiency of WSN is measured in terms of the total distance between the nodes to the base station and the amount of data transferred. The cluster head is responsible for creating the clusters and the cluster nodes affect the performance of the cluster. The result of the proposed work is efficient in terms of energy efficiency, load balancing and the number of senso nodes that die during the network time .
Sheetal Chhabra.et.al (2014) In this paper author proposed a clustering algorithm for load balancing. This enhanced algorithm improve the network lifetime and the scalability of the WSN. In this enhanced algorithm an efficient load balancing clustering technique is proposed. This technique is used for finding energy efficiency and better cluster head management. This algorithm is based on min heap algorithm and we use this for measuring performance analysis of
Network life time, Average no of cluster formation in each round, load balancing and data transmitted. Cluster head is a main part which creates clusters and the cluster nodes affect the performance of cluster. The result show that proposed algorithm is efficient in terms of amount of data to be transmitted, energy efficiency number of alive nodes in each round .
Nikhil Marriwala.et.al(2012)- In WSN small devices are present called sensor nodes these are fitted with sensors to monitor the physical and environmental conditions such as speed pressure, humidity, temperature, motion, etc. The nodes in WSN are dependent on battery so this is the issue of the WSN. Maximizing network lifetime and Minimizing energy dissipation are important issues in the designing of sensor networks, its applications and its protocol. In this the author improve the lifetime of the WSN in terms of the alive nodes in the network by using a different method for selecting the cluster head. The cluster head is selected on the basis of maximum residual energy and minimum distance and chooses a optimal path between cluster heads for transmitting the data to the base station .
In this paper we proposed a protocol LEACH_HE_MH on the basis of LEACH protocol and use Homogenous WSN. This proposed protocol overcome the issues of LEACH like security and energy consumption. In this proposed protocol we use the same round as in LEACH. The amount of energy consumption is a important factor in hierarchical routing protocol which affect the performance of the routing protocol when the communication is held between BS and CH. Energy used in this node much more than the other nodes. The limited amount of data is transmitted to the BS because aggregation function is applied to the data at CH before sending to the BS. If we apply public key cryptography scheme, the data is first decrypt by the CH and then apply aggregation function for removal of the redundant data and CH again encrypt the data and send to the BS. Hence in this method a lot of energy is consumed for encrypting and decrypting the data at CH. The LEACH_HE_MH is balance the energy consumption as well as provide security by implementing the homomorphic encryption and min-heap in LEACH protocol. Homomorphic encryption allows mathematical functions to be applied on data. In HE no need to decrypt the data. Hence with this encryption scheme the decryption of data by CH before applying aggregation function is not perform so energy wastage is not done. Min-heap allows better cluster head management to achieve load balancing. LEACH_HE_MH follows same Set-up phase as the simple LEACH. The only difference lies in steady state phase of LEACH_HE_MH.
19 aggregation function. The homomorphic encryption provide
security in LEACH.
2. The Min heap algorithm balance the load on network and provide energy efficient clusters.
The proposed algorithm: Set-Up Phase
1. Ch ══> n: idCh, Crc, Adv
2. Ni ──> CH: idNi, idCh, Crc, Join_Req
3. CH ══> n: idCh ,(… ,( idNi , TNi)…) , Crc ,Sched
Steady State Phase
4. Call Min-Heap
Ni ──> Ch : idCh ,Ci , Crc
Ci = E(mi , Pk)
(Sk , Pk) = KeyGen(γ)
5. Ch ──> BS: idCh , idBS , FHE((…,Ci,….) , Pk), Crc
FHE= Add (C1, C2, Pk) or
6. After receiving data from all the cluster heads, base station
decrypt the data to obtain the original data.
Dec(C, Sk) = mi ◊ mi+1
C=Ci + Ci+1 or C= Ci * Ci+1
◊= + or *
The symbol used in proposed algorithm denotes:
Ch, BS, Ni,: Cluster Head, , base station, ordinary node
n: Set of all nodes in the network
Adv,Join_Req,Sched: Message types string identifiers
Crc : Cyclic Redundancy Check
Ci ,mi: cipher text, plaintext
γ : Security Parameter
idCh, idNi , idBS : CH ,Nodes Ni, BS id’s respectively
<Y, TY>: A node id Y & its active slot TY in the clusters
══>, ──>: broadcast transmissions, Unicast, respectively
In this section we examine the performance of LEACH_HE_MH through NS 2.34 simulator. A network of 100 nodes is deployed in an area of 100m*100m with BS at
(50,175). The main parameters of the simulation experiments are described in Table 1.
TABLE I: PARAMETERS USED IN THE SIMULATION EXPERIMENT
Simulation Time 500Sec
No. of Nodes 100
BS location (65, 175)
Numbers of CH Variable
value 1000 M
Initial node power 2.5 J
Traffic Type CBR
MAC Protocol 802.11
Mobility Model Two Way Random
Routing Protocol LEACH
Consumed Energy, Data
and Alive nodes.
We compare LEACH_HE_MH protocol with LEACH, and use three performance metrics for the comparison, the consumption of the network’s energy numbers of nodes alive & the data amounts transmitted by the two different protocols. We also check the throughput of the LEACH_HE_MH.
Fig. 6 Energy Consumed vs. Time
20 and hence LEACH_HE_MH consumes less energy as
consumed by LEACH.
Fig. 7 Data Transmitted (bits) vs. Time
The figure 7 shows that data transmitted in LEACH_HE_MH is more as compared to LEACH initially but after some time it little bit decrease and last the equal amount of data is transmitted in LEACH_HE_MH and LEACH. This clearly shows that the min heap addition improve the performance.
Fig. 8 Nodes Alive vs. Time
The figure 8 shows that numbers of nodes alive in LEACH_HE_MH are more as compared to LEACH at 500 sec but at the completion of simulation the number of nodes alive are equal in both protocol. So it shows that LEACH_HE_MH performance is better than LEACH.
Fig. 9 Throughput vs. Time
Throughput means no. of bits transmitted per seconds. The figure 9 shows that the throughput of the LEACH_HE_MH is increases after every seconds. So it means that the the transmission rate of the LEACH_HE_MH is increases with the time and min heap better the performance and homomorphism did not degrade the performance.
In this paper, we proposed a LEACH protocol with homomorphic encryption and min-heap for providing confidentiality and proper load balancing scheme for energy efficient LEACH protocol. If we use public key cryptography then large amount of energy is consumed. We have analyzed the behavior and different performance metrics for LEACH_HE_MH and LEACH. Graphs of performance comparison in figure 6-9 shows that LEACH_HE_MH
consumes less energy as consumed by LEACH.
LEACH_HE_MH transmits more number of bits as compared to LEACH_HE. Adding homomorphic encryption and min-heap to LEACH does not reduce the network lifetime nor does it consume extra energy. Hence these performance parameters depicts that adding homomorphic encryption and min heap to LEACH increases the performance. Research in the area of LEACH protocol in WSN is very huge and work on this is actively done. Due to the time constraint and code limitations the present work i.e. simulation of LEACH protocol with homomorphic encryption and min-heap was only focused on evaluating some selected performance metrics. The evaluation of LEACH_HE_MH discussed in this paper with some more performance metrics like average energy consumed, stability etc will be considered as future research work.
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