Smart Grid (SG) communication has recently received significant attentions to facilitate intelligent and distributed electric power transmission systems. The advent of the smart grid promises to user in an era that will bring intelligence, efficiency, and optimality to the power grid. Most of these challenges will occur as an Internet-like communications network is super imposed on top of the current power grid using wireless mesh network technologies with the 802.15.4, 802.11 and WiMAX Standards. Each of these will expose the power grid to security threats. Wireless communication offers the benefits of low cost, rapid deployment, shared communication medium, and mobility. It causes many security and privacy challenges. The concept of dynamic secret is applied to design an encryption scheme for smart grid in wireless communication. Between two parties of communication, the previous packets are coded as retransmission sequence, where retransmitted packet is marked as ―1‖ and the other is marked as ―0‖.During the communication, the retransmission sequence is generated at both sides to update the dynamic encryption key. Any missing or misjudging sequence would prevent the adversary from achieving key. A Smart Grid platform is built, employing the ZigBee protocol for wireless communication. The Simulation results show that the retransmission and packet loss in ZigBee communication are inevitable and unpredictable and it is impossible of the adversary to track the updating of dynamic encryption key. Even though the DES scheme can protect the encryption key from attackers, the hackers can obtain the keys some time, due to the block size 64 bits used by DES that makes the adversary (hacker) to hack the data. It introduces vulnerabilities and liner crypt analysis; this can be achieved by using AES scheme. The AES uses 128 bits block size for a single encryption key a data of 256 billion gigabytes can be transmitted thus its provide much more safety to user from hacker and it reduces the end to end delay and increases packet transmission rate.

1. INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
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Certain Investigations on Security Issues in Smart Grid
over Wireless Communication
S.Fathima1
1
PG Scholar, Department of Computer Science and Engineering
SNS College of Technology Coimbatore,
Dr.S.Karthik2
Dean & Professor, Department of Computer Science and Engineering
SNS College of Technology Coimbatore,
Abstract— Smart Grid (SG) communication has recently received significant attentions to facilitate intelligent and distributed electric power
transmission systems. The advent of the smart grid promises to user in an era that will bring intelligence, efficiency, and optimality to the
power grid. Most of these challenges will occur as an Internet-like communications network is super imposed on top of the current power
grid using wireless mesh network technologies with the 802.15.4, 802.11 and WiMAX Standards. Each of these will expose the power grid to
security threats. Wireless communication offers the benefits of low cost, rapid deployment, shared communication medium, and mobility. It
causes many security and privacy challenges. The concept of dynamic secret is applied to design an encryption scheme for smart grid in
wireless communication. Between two parties of communication, the previous packets are coded as retransmission sequence, where
retransmitted packet is marked as ―1‖ and the other is marked as ―0‖.During the communication, the retransmission sequence is generated at
both sides to update the dynamic encryption key. Any missing or misjudging sequence would prevent the adversary from achieving key. A
Smart Grid platform is built, employing the ZigBee protocol for wireless communication. The Simulation results show that the retransmission
and packet loss in ZigBee communication are inevitable and unpredictable and it is impossible of the adversary to track the updating of
dynamic encryption key. Even though the DES scheme can protect the encryption key from attackers, the hackers can obtain the keys some
time, due to the block size 64 bits used by DES that makes the adversary (hacker) to hack the data. It introduces vulnerabilities and liner crypt
analysis; this can be achieved by using AES scheme. The AES uses 128 bits block size for a single encryption key a data of 256 billion
gigabytes can be transmitted thus its provide much more safety to user from hacker and it reduces the end to end delay and increases packet
transmission rate.
Index Terms— Analyzing Module (AM), Clonal Rate(CR), Smart Grid(SG), WiMAX, ZIGBEE.
——————————  ——————————
1 INTRODUCTION
The Smart Grid (SG) is considered as a desirable infrastructure
for energy efficient consumption and transmission, where the build-
in information flow, facilitate significant penetration of renewable
energy sources into the grid, and empower consumer with tools for
optimized energy consumption. Essentially, its aim is to create a
more flexible, efficient, and reliable power grid. And at the heart of
smart grid infrastructure is the communications network.
Cryptography is a method of storing and transmitting data in a
particular form so that only those for whom it is intended can read
and process it. Cryptography is closely related to the disciplines of
cryptology and cryptanalysis. Cryptography includes techniques
such as microdots, merging words with images, and other ways to
hide information in storage or transit. Cryptography is most often
associated with scrambling plaintext (ordinary text, sometimes
referred to as clear text) into cipher text (a process called
encryption), then back again (known as decryption). Individuals who
practice this field are known as cryptographers. Cryptography plays
a significant role in improving the integrity and confidentiality of the
data in SG. Symmetric cryptographies, such as DES (Data
Encryption Standard), Triple AES (Advanced Encryption Standard),
are widely employed in SG to effectively defend against possible
threats.
Zigbee is a specification for a suite of high-level communication
protocols used to create personal area networks built from small,
low-power digital radios. Zigbee is based on an IEEE 802.15
stanadard. Zigbee is a low-cost, low-power, wireless mesh network
standard targeted at wide development of long battery life devices in
wireless control and monitoring applications. Zigbee devices have
low latency, which further reduces average current. Zigbee chips are
typically integrated with radios and with microcontrollers that have
between 60-256 KB flash memory. Zigbee operates in the industrial
scientific and medical (ISM) radio bands. Data rates vary from 20
kbit/s (868 MHz band) to 250 kbit/s (2.4 GHz band).
1.1 Characteristics of Smart Grid
The principal characteristics of the Smart Grid include the
following,
 Self-healing
 Empowers and incorporates the consumer
 Tolerates security attacks
 Provides enhanced power quality
 Accommodates a wide variety of generation
options
1.2 Advantages of Smart Grid
 The Smart Grid helps determine the life cycle of power
generation and transmission equipment, schedule
preventive maintenance on time.
 The use of robust two-way communication, advanced
sensors, and distributed computing technology improves all
round efficiency, reliability, and safety of energy
transmissions.
 It is greatly helpful to the users in remote areas to get in
touch through wireless communication.
 A modernization of Smart Grid improves the end-use
devices and appliances.
 It decreased customer discontent, greater personal and
economic security, and greater confidence in public
governance.
2. RELATED WORK
Yichi Zhang et al. proposed that a distributed intrusion detection
system for smart grid (SGDIDS) by developing and deploying an
intelligent module, the analyzing module (AM), in multiple layers of

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the smart grid. Multiple AMs is embedded at each level of the smart
grid to improve detection and classify malicious data and possible
cyber attacks. In this paper it achieves effective analysis of
communication traffic and detects the type of attack, its occurrence
into the communication system. But the paper not proposed the
optimal combination of different classification techniques and
different Intrusion Detection System (IDS) for achieving a higher
overall accuracy for intrusion detection. Thus, the scheme is
subjected to vulnerabilities. AffinityThresholdScalar(ATS), Clonal
Rate(CR), Hyper mutation Rate(HR), Stimulation Threshold(ST)
were the parameters considered.
Merits
 Effective analysis of communication traffic.
 It is possible to detect the type of attack, it’s occurrence
into the communication system
Demerits
 The scheme is subjected to vulnerabilities
3. DYNAMIC ENCRYPTION SCHEME FOR SMART GRID IN WIRELESS
COMMUNICATION
Integrating information network into power system is the key
for realizing the vision of smart grid (SG), but also introduces many
security problems. Smart grid is a network of computer and
infrastructures to monitor and manage energy usage. Wireless
communication offers the benefits of low cost, rapid deployment,
shared communication medium, and mobility; at the same time, it
causes many security and privacy challenges during transmission.
The concept of dynamic secret is applied to design an encryption
scheme for smart grid wireless communication. Synchronous data
transmission between sender and receiver using OTF (One Time
Frame), within the time data transmission and acknowledgement
from receiver will be completed, that is treated as OTF. A node
which doesn’t produce the ACK within the time can cause packet
loss where retransmission of packet/data again is done. During the
communication, the retransmission sequence is generated at both
sides to update the dynamic encryption key. Any missing or
misjudging in retransmission sequence would prevent the adversary
from achieving the keys. The retransmission and packet loss in
ZigBee communication are inevitable and unpredictable, and it is
impossible for the adversary to track the updating of the dynamic
encryption key.
3.1 Methodology
The dynamic secret based encryption in smart grid is employed
for securing wireless communication. The basic idea of dynamic
secret is that the legitimate users dynamically generate a shared
symmetric secret key utilizing the inevitable transmission errors and
other random factors in wireless communication.
3.1.1 Smart Grid
The smart grid (SG) is considered as a desirable infrastructure
for energy efficient consumption and transmission, where the built-in
information networks support two-way energy and information flow,
facilitate significant penetration of renewable energy sources into the
grid, and empower consumer with tools for optimized energy
consumption.
3.1.2 Dynamic Secret:
The sender and receiver monitor the error retransmission in link
layer to synchronously select a group of frames. These frames are
hashed into dynamic secret to encrypt the data.
This part is a brief introduction of dynamic secret as follows,
i) Retransmission analysis /OTF set generation:
On the link layer’s communication, error retransmission
happens unavoidable and randomly at both side of the sender and the
receiver. According to Stop-and-Wait (SW) protocol, the sender
transmits a frame and waits for the corresponding acknowledgement
before sending a new frame. If a frame is only transmitted once and
its acknowledgement frame is received in time, this frame is named
as one time frame (OTF).
ii) Dynamic secret generation:
The number of OTF set ¥ reaches the threshold ((length of RS),
the sender and receiver agree on a uniformly random choice of
universal-2 hash functions to compress into the dynamic secret.
Then, the set ¥ is reset to empty.
iii) Encryption/Decryption:
When a new dynamic secret is generated, it will be applied to
update the encryption key at both sides of communication. This
symmetric encryption key is used to encrypt the data at sender and
decrypt the cipher at receiver. To reduce the computation
consumption, the XOR function is used for encryption and
decryption.
3.1.3 DSE Scheme for SG Wireless Communication:
Dynamic secret-based encryption (DSE) scheme is designed to
secure the wireless communication between the smart devices and
control center.The DSE scheme consists of retransmission sequence
generation (RSG), DS generation (DSG), and encrypt/decrypt.
i. Retransmission Sequence Generation (RSG):
This module is applied to monitor the link layer error
retransmission. The communication packets which have been
retransmitted are marked as ―1‖ and the nonretransmitted packets
are marked as ―0.‖ The pervious packets are coded as 0/1 sequence
¥, named as retransmission sequence (RS).In DSE, RS is applied to
replace the OTF set for dynamic secret generation due to the
limitation of computation capability and storage resources.
ii. Dynamic Secret Generation (DSG):
Once ¥ reaches the threshold (length of RS), it would be compressed
to a DS in DSG module. Considering the limitation on computation
power, the hash functions are recommended in DSG module.
a) Encrypt/Decrypt:
The new dynamic secret is applied to update the dynamic
encryption key (DEK) by
DEK(k) is generated at both sides of communication
synchronously. The sender applies it to encrypt the Data, and the
receiver applies it to decrypt the Cipher. XOR function, as one of the
most light-weight and easy-implementation algorithm, is applied to
update the DEK and encrypt/decrypt the data on both sides. If DEK
is shorter than the data, DEK(k) is replicated and padded circularly to
generate whose length is equal to the raw data or cipher text.
DSE scheme is an appropriate solution for securing SG wireless
communication. It can prevent eavesdropping and forging by
utilizing the inevitable errors in wireless communication; can reduce
the cost on computation and storage by applying the simple
algorithms; can self-organize and self-manage.
3.1.4 Attack case in Smart Grid
A smart grid platform is constructed to investigate how the
attacker intercepts the communication of smart meter and injects bad
data into smart meter.
a) Smart grid Platform

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It established with three sides: Smart Terminal (ST), Control
Center (CC), and Adversary. IEEE 802.15.4 standard defines the
physical and MAC layers of ZigBee, while the ZigBee Alliance
defines the network and application layers. Since it is designed as a
low cost, low rate, low power and low complexity personal area
network.
b) Smart terminal
Smart meters are applied to monitor a micro power grid
including various electronic devices for displaying, storing, and
monitoring all relevant system parameters, such as voltages, currents
et al.
c) Control Center(CC)
Several computers are deployed as the CC . On the CC, the
ZigBee module is set as normal mode to communicate with ST.
d) Adversary
On the Adversary, it is set as promiscuous mode to eavesdrop
the communication between the ST and CC.
e) Smart grid attack cases
Most terminal devices in smart grid are connected into intranet,
such as smart sensors and intelligent applications. It is believed that
the malicious users could not access them without the intranet and
Mac address of these devices. The Adversary obtains the address of
the smart meter by monitoring their communication and then injects
the false data into the meter. The Adversary can capture the packet
sent from ST through Zigbee. The address of ZigBee module on
Smart Meter and the short address of coordinator on control center
the measurement can be decoded from the data part of the packet.
Using the captured address, attacker can access the smart meter and
inject false data.
f) Analysis
To analyze the security of DSE, the difference between the RS
on the CC and Adversary should be listed. Then, retransmitted
packet ratio (RPR), packet loss ratio (PLR) and length of RS (L_RS)
are investigated to guide the design of DSE. The number of packets
is transmitted per seconds; the attacker can capture the data without
knowing the packet loss. Control center again retransmit the loss of
data to the terminal. Then attacker can generate the dynamic secret
with the false data and fail to track the DEK without knowledge of
retransmission again he could not start it from the beginning. Thus it
is difficult for the attacker to brute force crack the RS. If the
Adversary tries to crack the RS, the complexity is related to three
key factors: the number of retransmitted packets, the lost packets of
the Adversary and the length of the RS.
4. PARAMETERS
The performance of network were evaluated using the following
metrics,
4.1 Retransmitted Packet Ratio(RPR):
The complexity of RS is determined by the number of the
retransmitted packet. For example, if there is no retransmitted or
non-retransmitted packet, the RS is all-zeroes or all-ones; if there is
only 1 retransmitted packet, the Adversary can easily crack the RS
using brute force. Thus, we need enough retransmitted and non-
retransmitted packets to prevent against the brute force cracking. The
number of retransmitted packet is determined by two factors: the
RPR and the L_RS.
4.2 Packet Loss Ratio
It is the ratio of the number of data packets loss occurs when
one or more packets of data travelling across a computer network fail
to reach their destination.
4.3 Packet Delivery Ratio
It is the ratio of the number of data packets successfully
received by the CBR destinations to the number of data packets
generated by the CBR sources.
4.4 Average End – to – End Delay
It represents the average delay of successfully delivered CBR
packets from source to destination node. It includes all possible
delays from the CBR sources to destinations.
5. RESULTS AND DISCUSSIONS
The evaluation of performance of the Secure Smart Grid (SSG)
protocol was evaluated by comparing it with AODV protocol using
NS - 2 Simulator. The security mechanism in Smart Grid makes use
of data transmission. Here, the analysis is done for security in data
transmission. For comparing the security performance of SSG
protocol, a dynamic secret based encryption scheme is used for
reducing the security issues of data packet during data transmission.
5.1 Performance Analysis for Retransmitted Rate between
AODV Vs. SSG
In AODV protocol due to packet loss which leads to excessive
packet transmission. It is severe when the number of nodes increases.
It is important to reduce retransmission and packet drops. Compared
with AODV protocol, the SSG protocol reduces the rate of
Retransmission.
Figure 3.2: Performance Analysis for Retransmission Rate between
AODV Vs. SSG
5.2 Performance Analysis for Packet Delivery Ratio between
AODV Vs. SSG
The SSG protocol can increase the packet delivery ratio due to
the reduction in security issues and also parallely reduces the packet
drops. On average the packet delivery ratio in SSG protocols is
improved when compared with the AODV protocol.
Figure 3.3: Performance Analysis for Packet Delivery Ratio between
AODV Vs. SSG
5.3 Performance Analysis for Average End – to – End Delay
between AODV Vs. SSG
The SSG protocol reduces the average end – to – end delay due
to a decrease in number of packet drops. The retransmission
increases delay due to too many collisions and interferences thus
leading to excessive packet drops and also increases the number of

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retransmissions. Thus, reducing the retransmission of data packets
the delay can be decreased.
Figure 3.4: Performance Analysis for Average End – to – End Delay
between AODV Vs. SSG
5.4 Performance Analysis for Packet Loss between AODV Vs.
SSG
The SSG protocol significantly reduces the security issues
during the packet transmission. By applying security mechanism to
transmission it reduces the congestion and collision. Thus, compared
with AODV protocol it’s reduces the number of packet loss during
transmission.
Figure 3.5: Performance Analysis for Packet Loss between AODV
Vs. SSG
6. CONCLUSION
A dynamic secret-based encryption scheme is designed to secure
the wireless communication of SG. The DSE scheme can protect the
users against eavesdropping by updating the dynamic encryption key
with retransmission sequence in communication, even the attackers
know the details of DSE scheme and obtain the encryption key at
some time. It is self-contained, that is, it is dynamically generated
during the normal communication without additional traffic and
control command. The generated simulation results depicts the
security issues thus reducing the retransmission of packets due to
packet loss and increase the packet delivery ratio and thus decreasing
the end – to – end delay. But the performance gets reduced, since the
security issues do not properly overcome by Dynamic secret based
encryption. The problem is overcome by using Electing trust head
which reduces the retransmission rate and increased packet delivery
ratio and decreased end to end delay during transmission.
REFERENCES
1. R.Moghe, F. C. Lambert, and D. Divan, ―Smart ―Stick-on‖
sensors for the smart grid,‖ IEEE Trans. Smart Grid, vol. 3, pp. 241–
252, 2012.
2. M. M. Fouda, Z. M. Fadlullah, N. Kato, L. Rongxing, and S.
Xuemin,―A lightweight message authentication scheme for smart
grid communications,‖IEEE Trans. Smart Grid, vol. 2, pp. 675–685,
2011.
3. Z. Yichi, W. Lingfeng, S. Weiqing, R. C. Green, and M. Alam,
―Distributed intrusion detection system in a multi-layer network
architecture of smart grids,‖ IEEE Trans. Smart Grid, vol. 2, pp. 796–
808,201.
4. J. Xia and Y.Wang, ―Secure key distribution for the smart grid,‖
IEEE Trans. Smart Grid, vol. 3, pp. 437–1443, 2012.
5. L. Rongxing, L. Xiaohui, L. Xu, L. Xiaodong, and S. Xuemin,
―EPPA:An efficient and privacy-reserving aggregation scheme for
secure smart grid communications,‖ IEEE Trans. Parallel Distrib.
Syst., vol.23, pp. 1621– 1631, 2012.
6. Zhong Fan, Parag Kulkarni, Sedat Gormus, Costas Efthymiou,
Georgios Kalogridis, Mahesh Sooriyabandara, Ziming Zhu,
Sangarapillai Lambotharan, and Woon Hau Chin, ―Smart Grid
Communications: Overview of Research Challenges, Solutions, and
Standardization Activities,‖ IEEE Communications surveys &
Tutorials, vol.15,No. 1, First Quarter 2013.
7. Y. Ye, Q. Yi, and H. Sharif, ―A secure data aggregation and
dispatch scheme for home area networks in smart grid,‖ in Proc. 2011
IEEE Global Telecommun. Conf., pp. 1–6.
8. H. Li, S. Gong, L. Lai, Z. Han, R. Q. Qiu, and D. Yang,
―Efficient and secure wireless communications for advanced
metering infrastructure in smart grids,‖ IEEE Trans. Smart Grid, vol.
3, pp. 1540–1551, 2012.
9. T. Liu, Y. Gu,D.Wang, Y. Gui, and X. Guan, ―A novel method to
detect bad data injection attack in smart grid,‖ in Proc. IEEE
INFOCOM
Workshop Commun. Control Smart Energy Syst..
10. S.Fathima, Dr.S.Karthick, Mrs.R.M.Bhavadharani, ―Overview
on Network Security and its Vulnarabilities‖,International Journal of
Recent and Innovation Treands in Computing and Communicatiion,
vol.2,Issue:8,August 2014.