29-12-2012, 06:15 PM
Security in Wireless Sensor Network: A survey
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Abstract
Wireless Sensor Network is an emerging
technology that shows great promise for various futuristic
applications both for mass public and military. The sensing
technology combined with processing power and wireless
communication makes it lucrative for being exploited in
abundance future. The inclusion of wireless communication
technology also incurs various types of security threats.
However, like any other system, security is one of the
important issues in any WSN application. The intent of this
paper is to investigate the security attacks and mechanism that
apply to wireless sensor network. It also discusses Trust
Management issue that is important in security.
INTRODUCTION
Wireless Sensor Network is composed of large number of
sensor nodes that are scattered in harsh environment. This
network is like any other network is prone to various
security issues. So understanding security of wireless sensor
network is important issue. There are so many mechanisms
are developed to provide the security to sensor network or
node. One of the important issue in security of wireless
sensor network is trust management.
This paper organized as follows: Section II contain
Introduction to wireless sensor network and its security.
Section III describes security mechanism that applies to
wireless sensor network. Section IV contains classification
of security and Section V consists of Trust Management.
Section VI concludes the paper.
SECURITY IN WIRELESS SENSOR NETWORK
A wireless sensor network is a composed of large
number of nodes that are densely deployed either inside the
phenomenon or very close to it. It is spatially distributed
autonomous devices using sensors to cooperatively monitor
physical or environmental conditions, such as temperature,
sound, vibration, pressure, motion or pollutants, at different
locations. Wireless Sensor Network may operate in hostile
environment, so security is needed to ensure the integrity
and confidentiality of sensitive information.
Security is important field in WSNs, which is quite
different from traditional security mechanism. This is
because of two major reasons. Firstly, there are severe
constraints on these devices namely their minimal energy.
Key establishment and trust setup
The primary requirement of setting up the sensor
network is the establishment of cryptographic keys.
Generally the sensor devices have limited computational
power and the public key cryptographic primitives are too
expensive to follow. Key-establishment techniques need to
scale to networks with hundreds or thousands of nodes.
Sensor nodes may need to set up keys with their neighbors
and with data aggregation nodes. The disadvantage of this
approach is that attackers who compromised sufficiently and
many nodes could also reconstruct the complete key pool
and break the scheme. [2]
Secure data aggregation
The sensed values must be aggregated to avoid
overwhelming amounts of traffic back to the base station.
For example, the system may average the temperature of a
geographic region, combine sensor values to compute the
location and velocity of a moving object, or aggregate data
to avoid false alarms in real-world event detection.
Depending on the architecture of the wireless sensor
network, aggregation may take place in many places in the
network. All aggregation locations must be secured. [3]
Intrusion detection
Intrusion detection as it applies to detecting attacks on
the sensor network itself, rather than the popular intrusion
detection application being researched for such uses as
perimeter monitoring, and so forth. Wireless sensor
networks are susceptible to many forms of intrusion.
Resilience to node capture
One of the most challenging issues in sensor networks is
resiliency against node capture attacks. In most applications,
sensor nodes are likely to be placed in locations easily
accessible to attackers. Such exposure raises the possibility
that an attacker might capture sensor nodes, extract
cryptographic secrets, modify their programming, or replace
them with malicious nodes under the control of the attacker.
Tamper-resistant packaging may be one defense, but it’s
expensive, since current technology does not provide a high
level of security. Algorithmic solutions to the problem of
node capture are preferable. [2]
Data Confidentiality
Data confidentiality is the most important issue in
network security. Every network with any security focus
will typically address this problem first. In sensor networks,
the confidentiality relates to the following:
A sensor network should not leak sensor readings to its
neighbors. Especially in a military application, the data
stored in the sensor node may be highly sensitive. In many
applications nodes communicate highly sensitive data, e.g.,
key distribution; therefore it is extremely important to build
a secure channel in a wireless sensor network. Public sensor
information, such as sensor identities and public keys,
should also be encrypted to some extent to protect against
traffic analysis attacks.
Data Integrity
With the implementation of confidentiality, an adversary
may be unable to steal information. However, this doesn’t
mean the data is safe. The adversary can change the data, so
as to send the sensor network into disarray. For example, a
malicious node may add some fragments or manipulate the
data within a packet. This new packet can then be sent to the
original receiver. Data loss or damage can even occur
without the presence of a malicious node due to the harsh
communication environment. Thus, data integrity ensures
that any received data has not been altered in transit.
Data Freshness
Even if confidentiality and data integrity are assured, we
also need to ensure the freshness of each message.
Informally, data freshness suggests that the data is recent,
and it ensures that no old messages have been replayed. This
requirement is especially important when there are sharedkey
strategies employed in the design. Typically shared keys
need to be changed over time. However, it takes time for
new shared keys to be propagated to the entire network. In
this case, it is easy for the adversary to use a replay attack.
Also, it is easy to disrupt the normal work of the sensor, if
the sensor is unaware of the new key change time. To solve
this problem a nonce, or another time-related counter, can
be added into the packet to ensure data freshness.
Sybil Attack
In many cases, the sensors in a wireless sensor network
might need to work together to accomplish a task, hence
they can use distribution of subtasks and redundancy of
information. In such a situation, a node can pretend to be
more than one node using the identities of other legitimate
nodes (Figure 4). This type of attack where a node forges
the identities of more than one node is the Sybil attack.
Sybil attack tries to degrade the integrity of data, security
and resource utilization that the distributed algorithm
attempts to achieve. Sybil attack can be performed for
attacking the distributed storage, routing mechanism, data
aggregation, voting, fair resource allocation and
misbehavior detection.
Denial of Service
The simplest DoS attack tries to exhaust the resources
available to the victim node, by sending extra unnecessary
packets and thus prevents legitimate network users from
accessing services or resources to which they are entitled.
DoS attack is meant not only for the adversary’s attempt to
subvert, disrupt, or destroy a network, but also for any event
that diminishes a network’s capability to provide a service.
In wireless sensor networks, several types of DoS attacks in
different layers might be performed. At physical layer the
DoS attacks could be jamming and tampering, at link layer,
collision, exhaustion, unfairness, at network layer, neglect
and greed, homing, misdirection, black holes and at
transport layer this attack could be performed by malicious
flooding and resynchronization. The mechanisms to prevent
DoS attacks include payment for network resources,
pushback, strong authentication and identification of traffic.
CONCLUSION
In this paper, we have presented the general concept of
wireless sensor network and security in wireless sensor
network. Current research so far focuses on the security of
wireless sensor network. There is various mechanism of
security that applies in our network so our network is more
prone to failure. We have also described so many attacks
that occur in sensor network and also apply to sensor node.
Additionally, the most important issue in security is Trust
management is also described. In future, so many attacks
will be introduced that are harm the sensor network and
sensor node, mechanism to prevent it.