Secure & Energy Efficient Routing for Hierarchical WSNs

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					    International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 3, September – October 2012                                    ISSN 2278-6856

                      Secure & Energy Efficient Routing for
                              Hierarchical WSNs
                                 Mr. Navneet Verma1 , Mr. S.C. Gupta2, Ms. Pooja Sethi3

         1, 2, 3
                   PIET Engineering College, Department of Computer Science & Engineering, SAMALKHA, Paniapt, 132103,
                                                           HARYANA, India

Abstract: In this paper security is implemented in WSNs           becoming the cluster heads. The steady state phase is
protocol LEACH-C. In WSNs though, energy efficiency is an         same as for the LEACH [11], [12] protocol. Due to this
important performance metric, directly influencing the            centralized approach base station has the global
network lifetime. The other important factor for WSNs is          knowledge of the network area, so less energy is
security, as sensor nodes communicate sensitive data, so it is    consumed by the complete network.
necessary to ensure that any intruder or other neighboring
network could not get confidential information intercepting
the transmissions.
Keywords: wireless sensor             networks, low energy
adaptive clustering hierarchy.

Wireless sensor networks are an emerging technology for
low-cost, unattended monitoring of a wide range of
environments. In WSNs sensor nodes are densely
deployed either inside the phenomenon or very close to it.
The wireless sensor node, being a small device, can only
be equipped with a limited power source. In some
application it is impossible to replacement of power
resources. WSNs are designed to monitor events and
report this information to a central location [2], or sink
node. The information is required to efficiently travel                  Figure 1: Centralized Hierarchical Routing
through the network. It is the job of the routing protocol                                 Protocol
[5] to officiate this process. In networking concepts,            The desired features of WSNs are security, reliability,
routing refers to select paths in a network along which to        robustness, self-healing and scalability. So our goal in
send data. The other important factor for WSNs is                 this paper is to achieve the data confidentiality by using
security, as sensor nodes communicate sensitive data, so it       Homomorphic encryption scheme on Energy Efficient
is necessary to ensure that any intruder or other                 Centralized Routing Protocol for Hierarchical WSNs”.
neighboring network could not get confidential
information intercepting the transmissions. One standard          2. HURDLES TO WSN SECURITY
security method of providing data confidentiality is to
encrypt data and use of shared key so that only intended          The following sector is the limitations in sensor networks
receivers can get the sensitive data.                             [4], [8-9] which make the design more complicated.
Many Routing protocols are existent in the wireless
sensor network, but we are working with LEACH-C. As                    a) Node limitations
LEACH-C protocol uses a centralized clustering                             A typical sensor node processor is of 4-8 MHz,
algorithm [3], [6] and the same steady state phase as in                   having 4KB of RAM, 128KB flash and ideally
LEACH protocol. LEACH-C produce better clusters by                         916 MHz of radio frequency. Heterogeneous
dispersing the cluster head nodes throughout the network.                  nature of sensor nodes is an additional limitation
In setup phase of LEACH-C each node sends its geo                          which prevents one security solution.
graphical location (using GPS technique) and the residual
energy level [1] to the base station. By this information,             b) Network limitations
base station computes the average energy level of the                      Beside node limitations, sensor networks bring
nodes and the nodes having the energy below this average                   all the limitations of a mobile ad hoc network
energy level cannot be the cluster head for the current                    where they lack physical infrastructure, and they
round. The remaining nodes have the probability of                         rely on insecure wireless media.

Volume 1, Issue 3 September-October 2012                                                                           Page 51
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 3, September – October 2012                                    ISSN 2278-6856

    c) Physical limitations                                   [16]. In this paper our goal is to achieve the onfidentiality
        Sensor networks deployment nature in public           of sensing data and Minimum Energy Consumption.
        and hostile environments in many applications
        makes them highly vulnerable to capture and           4. HOMOMORPHIC ENCRYPTION
        vandalism. Physically security of sensor nodes
                                                              A Homomorphic Encryption [7] scheme allows arithmetic
        with tamper proof material increases the node
                                                              operations on cipher texts. One example is a
                                                              multiplicatively homomorphic scheme, where the
                                                              decryption of the efficient manipulation of two cipher
    d) Memory limitations
                                                              texts yields the multiplication of the two corresponding
        In wireless sensor network, nodes have limited
                                                              plaintexts. Homomorphic encryption schemes are
        memory capability, having 4KB of RAM, 128KB
                                                              especially useful whenever some party not having the
                                                              decryption key(s) needs to perform arithmetic operations
                                                              on a set of cipher texts.
    e) Computational limitations
        Due to limited power supply to the sensor nodes,
                                                                4.1 ENCRYPTION SCHEME USING RANDOM
        complex computational algorithms that are used
        on normal computers may not be directly
                                                              The main idea is to replace the xor (exclusive-OR)
        applicable to the WSNs.
                                                              operation typically found in stream ciphers with modular
                                                              addition. The basic scheme is as follows:
                                                              Basic Additively Homomorphic [3] Encryption Scheme:-
The aim of security principles in WSNs is to secure the       Encryption:
information and resources from attacks and misbehavior.        (1) Represent message m an integer m Є [0, M -1]
The security requirements [7], [9] in WSNs include:                 where M is the modulus.
                                                               (2) Let k be randomly generated key stream, where k
    a) Availability, which ensures that the desired                 Є [0, M - 1].
        network services are available even in the             (3) Compute c = Enc k (m) = m+ k mod M.
        presence of denial-of-service attacks.
    b) Confidentiality, which ensures that a given            Decryption:
        message cannot be understood by anyone other             (1) Deck(c) = c - k mod M.
        than the desired recipients.
    c) Integrity, which ensures that a message sent from      Addition of Cipher texts:
        one node to another, is not modified by                  (1) Let c1 = Enc k1 (m1)
        malicious intermediate nodes.                                 and c2 = Enc k2 (m2).
    d) Authorization, which ensures that only
        authorized sensors, can be involved in providing      Aggregated cipher text:
        information to network services.                         (2) cl = c1 + c2 mod M = Enc k (m1 + m2) Where k
    e) Authentication, which ensures that the                         = k1 + k2 mod M.
        communication from one node to another node is
        genuine, that is, a malicious node cannot             The correctness of aggregation [3], [15] is assured if M is
        masquerade as a trusted network node.                 sufficiently large.
    f) Non-repudiation, which denotes that a node             The reason is as follows:
        cannot deny sending a message.                        c1 = m1 + k1 mod M and c2 = m2 + k2 mod M. Then cl
    g) Freshness, which implies that the data is recent       = c1 + c2 mod M = (m1 + m2) + (k1 + k2) mod M =
        and ensures that no adversary can replay old          Enck1+k2 (m1 + m2).
        messages. Moreover, as new sensors are                For k = k1+k2, Dec k(cl ) = cl -k mod M =
        deployed and old sensors fail, we suggest that        (m1+m2)+(k1+k2)-(k1+k2) mod M = m1 +m2 mod M.
        forward and backward secrecy should also be
        considered: Forward secrecy: a sensor should not      We assume that m < M. Note that, if n different ciphers ci
        be able to read any future messages after it leaves   are added, M must be larger than ni=1mi. Otherwise,
        the network. Backward secrecy: a joining sensor       correctness does not hold. In fact, if n i=1mi > M,
        should not be able to read any previously             decryption produces m < M.
        transmitted message.                                  Note that this basic scheme is provided for illustration
The security principles in WSNs are usually focused on        purposes only and does not represent the actual
cryptography. However, due to the constraints in WSNs,        construction. Since the encryption key k, is assumed to be
many already existing secure algorithms are not practical     randomly chosen by each sensor node in every reporting
                                                              session, a secure channel has to be maintained at all times

Volume 1, Issue 3 September-October 2012                                                                         Page 52
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 3, September – October 2012                                    ISSN 2278-6856

between each sensor node and the sink. In the actual
construction, such a secure channel is not required.          Figure 2: A Comparison of LEACH-C’s Avg. Energy

5. ADVANTAGES AND DISADVANTAGES OF                          Table 1: Energy consumption [14] by sensor for same no
HOMOMORPHIC ENCRYPTION                                                           of rounds

    a) Trapdoor Encryption: Homomorphic Encryption                       LEACH-C                Secure LEACH-C
        makes it possible to give user a way to perform               (energy in joules)        (energy in joules)
        some operation on encrypted data without                            .07j                       .12j
        decryption key. So we are using the same                             .14j                       .25j
        property in this paper, the cluster head is doing
        aggregation operation [8] on encrypted data.                         .25j                       .33j
    b) Secret Sharing: In cryptography, secret sharing                       .32j                       .44j
        means that a secret is sharing between several                       .39j                       .55j
        parties in such a way that no single party can
        retrieve the secret.                                                 .64j                       .85j
                                                                             .75j                       .95j
Disadvantage of using homomorphic encryption function
is that nodes have to maintain more data base and also it                    1.16j                     1.42j
is energy consuming task.                                                    1.57j                     1.75j
                                                                             1.70j                     1.85j
The sole criterion for evaluation is based on the amount
of energy consumption for achieving the security by
Homomorphic encryption scheme for LEACH-C. In this          7. CONCLUSION & FUTURE SCOPE
paper we are using the Homomorphic additive function        In this paper, we look at routing protocols, which can
for encryption. The figure 1.2 shows the comparison of      have a significant impact on the overall reliability and
average energy dissipation by LEACH-C [10] (with and        energy dissipation of these networks. In LEACH-C, the
without encryption) for the same numbers of rounds.         base station first collects information about the logical
Throughout the simulations we consider network node         structure of the network and residual energy of each node.
configuration with 100 nodes where, each node is            So, with the global information about the network, base
assigned an initial energy of 2 Joules. Figure 1.2 shows    station does cluster formation better in the sense that it
the average energy dissipation of the protocols under       has information about the residual energy of each node.
study over the number of rounds of operation. This plot     Finally, secure LEACH-C is compared with LEACH-C
clearly shows that LEACH-C (without security) has a         protocol. In future scope we can try to achieve others
much more desirable energy expenditure curve than that      principles of security like data availability, integrity,
of secure LEACH-C. On average, secure LEACH-C               authentication and non-repudiation etc.
consumes 05 percent extra energy to achieve encryption
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Volume 1, Issue 3 September-October 2012                                                                       Page 53
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 3, September – October 2012                                    ISSN 2278-6856

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Description: International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: Email:, Volume 1, Issue 3, September – October 2012 ISSN 2278-6856