Security Challenges And Implementation Mechanism For Vehicular Ad Hoc Network

Abstract

Vehicular Ad Hoc Networks (VANET) is an emerging and promising technology, this technology is a fertile region for attackers, who will try to challenge the network with their malicious attacks. The security of VANET has mostly directed the attention of today research efforts, while comprehensive solutions to protect the network from adversary and attacks still need to be improved, trying to reach a satisfactory level, for the driver and manufacturer to achieve safety of life and infotainment. We discuss the need for robust VANET networks which is strongly dependent on their security and privacy features. VANET facing many challenges that been addressed in this research, we also discuss a set of solutions presented for these challenges and problems; and we made critics for these solutions.

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Security Challenges And Implementation
Mechanism For Vehicular Ad Hoc Network
Mostofa Kamal Nasir, A.S.M. Delowar Hossain, Md. Sazzad Hossain, Md. Mosaddik Hasan, Md. Belayet Ali
Abstract: - Vehicular Ad Hoc Networks (VANET) is an emerging and promising technology, this technology is a fertile region for attackers, who will try to
challenge the network with their malicious attacks. The security of VANET has mostly directed the attention of today research efforts, while
comprehensive solutions to protect the network from adversary and attacks still need to be improved, trying to reach a satisfactory level, for the driver
and manufacturer to achieve safety of life and infotainment. We discuss the need for robust VANET networks which is strongly dependent on their
security and privacy features. VANET facing many challenges that been addressed in this research, we also discuss a set of solutions presented for
these challenges and problems; and we made critics for these solutions.
Index Terms: - VANET, MANET, PKI, VLP, EPKI, EDR, ECC, PCKS
————————————————————
1 INTRODUCTION
VANET is a new type of network which is expected to support
a huge spectrum of mobile distributed applications that
operated in vehicles. The most significant services in VANET
on the roads are that it can give drivers safety in driving.
VANET can disseminate useful information about road and
traffic situation as well as other noticeable information for
people who drive in the range of the typical road. VANET is
part of Mobile Ad Hoc Networks (MANET), this means that
every node can move freely within the network coverage and
stay connected, each node can communicate with other nodes
in single hop or multi hop, and any node could be Vehicle,
Road Side Unit (RSU). VANET is differing from MANET in a
way that nodes in VANETs have improved processing and
storage capabilities. Hence with perpetual increase in
concentration of vehicles on roads and the ability to
communicate over wireless medium, VANETs an inspiring
platform for Intelligent Transportation Systems (ITS) for better
and safer commuting.
ITS applications have three broad categories such as safety,
non safety and infotainment. These applications further
categories to accidents, intersection, road congestion, user
application, internet connectivity and peer-to-peer application.
The security of VANETs is one of the most decisive issues
because their information is broadcast in open access
environments. It is necessary that all transmitted data cannot
be injected or changed by users who have malicious goals.
Moreover, the system must be able to detect the obligation of
drivers while still maintaining their privacy. These problems in
VANET are difficult to solve because of the network size, the
speed of the vehicles, their relative geographic positions, and
the randomness of the connectivity between them. It is critical
for VANET to meet robust security policy to ensure users
about issues that can make them worry. VANET security
should satisfy four goals, it should ensure that the information
received is correct (information authenticity), the source is who
he claims to be (message integrity and source authentication),
the node sending the message cannot be identified and
tracked (privacy) and the system is robust [1]. To guard
against misuse activities, the overall organization for VANET
security architecture must be carefully designed especially
when it is a worldwide implemented in VANET. Our paper
presents in section 2 Security of VANET in section 3 types of
attack in VANET, in section 4 VANET security challenges, in
section 5 security mechanism of VANET which is followed by
conclusion.
2 VANET SECURITY
The security of VANETs is one of the most critical issues
because their information transmission is propagated in open
access environments. It is necessary that all transmitted data
cannot be injected or changed by users who have malicious
goals. Moreover, the system must be able to detect the
obligation of drivers while still maintaining their privacy. These
problems in VANET are difficult to solve because In terms of
security implementation, there are several layers which are
used in proposed protocols to deploy security policies but one
of the most often-used levels is layer three for implementation
security [2]. There are several methods to assure security in
the network world which are also applicable in wireless
networks. An overview of 802.11p protocol’s Media Access
Control layer and the location of security sub-layer are
illustrated in Figure 1. Thus, most of protocol implementers
prefer using cryptography schemes such as public key. In
addition, there are other standard solutions for meeting
————————————————
 Mostofa kamal Nasir is working as an Asstant
Professor of the Department of Computer Science and
Engineering of Mawlana Bhashani Science and
Technology University, Santosh, Tangail, Bangladesh.
Email: kamal.mostofa@gmail.com
 A.S.M. Delowar Hossain is working as an Asstant
Professor of the Department of Computer Science and
Engineering of Mawlana Bhashani Science and
Technology University, Santosh, Tangail, Bangladesh.
Email: uzzal35@yahoo.com
 Md. Sazzad Hossain is working as an Asstant
Professor of the Department of Computer Science and
Engineering of Mawlana Bhashani Science and
Technology University, Santosh, Tangail, Bangladesh.
Email: sazzad_101@yahoo.com
 Md. Mosadddik Hasan is working as an Asstant
Professor of the Department of Computer Science and
Engineering of Mawlana Bhashani Science and
Technology University, Santosh, Tangail, Bangladesh.
Email: shohug_0301012@yahoo.com
 Md. Belayet Ali is working as an Asstant Professor of
the Department of Computer Science and Engineering
of Mawlana Bhashani Science and Technology
University, Santosh, Tangail, Bangladesh.
Email: belayet_2003@yahoo.com

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security patterns as IPSec for ensuring other aspects of
security. The main idea of the security issue besides trust is
allowing each car to constitute a local communication area
around itself . In this way, each car can exchange vital signs
with the neighboring vehicles. Security in VANETs can be
improved only after experiencing and issuing models as
Fig-1:
Overview
of VANET
s
e
cur
i
ty
discussed in [3]. First of all, the attacker must be identified and
the main principles that guide his attack and for this reason we
use basic assumptions about the attacker based on what we
can observe as damage from the attack.
3 TYPES OF ATTACK
First of all it is necessary to identify the threats that exist in
VANET's and the way those threats can affect the
performance and the integrity of the network. Describing
threats and certain attacks can be of real use when thinking
about the practical and theoretical solutions of these problems.
Therefore we categorize security threats into three groups
according to the application type that they target according to
the works like [4], [5], [6] and [7]. Possible attacks in the
network can be various types, active, passive, control of
movement, falsification of data etc.
3.1 Classification Based on Nature
Depending on the nature attacks can be classified according
to fig. 2.
 Active vs. passive: An active attacker is a node that can
generate packets and placing on the network, while
passive one is that can only push the message in the
network. False information: Attackers are spread wrong
information in the network to influence the behavior of
other vehicles [8].
 False position: Attackers use this technique of attack to
alter the fields related to their position, speed, and
direction of travel by broadcast messages. In the worst
case, the attacker can clone other vehicles, hiding in this
way their presence in case of accidents, and avoiding any
responsibility [9].
 Vehicle tracking: This is the scenario of like big brother,
where a global observer can control the routes of the
vehicles designated to use and the observed data for
various purposes (for example, some companies that rent
cars can trace their cars). To make such a control the
"global observer" could control infrastructure such as
roads or vehicles in a given geographical location. In this
case, the attack is the passive type. We assume that the
attacker does not use cameras or devices for tracking
physically of a vehicle which wants to discover the
identity. This assumption is made to create a scenario
feasible in terms of manufacturing cost even if the
application of devices such as cameras would give
considerable aid to the controls of vehicles.
 Internal vs. external: Any attacks by internal nodes are
part of the network. This means that the attacker node is a
member of the network. Whereas any attacks by external
nodes is considered by the network as an intruder.
Generally attacks by internal nodes are most effective as
they treats authenticated by the network.
 False GPS signal: The vehicles that use GPS are easily
vulnerable to various attacks such as the GPS signal.
 Denial of service: In this style of attack a node may want
to block the services offered by VANET or even may want
to cause an accident. Examples of attack can be flooding
the network with fake messages or blocking transmissions
in the network itself. This kind of attack has no intention to
make profit by the malignant node.
Fig.2: Classification of the attacks in VANET

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An example of attack in VANET shows in Figure 3. In this
figure two vehicles A2 and A3 enter false information within a
network for changing the flow of traffic of the road and obtain a
useful result.
3.2 Classification of attacks according to the region
Attacks based on the area of interest are those attacks based
on geographical data. We define the attack nodes of an area
of interest by "victim nodes ". The area of interest may be
limited or extended. Characteristic of this kind of attack is the
potential expansion of the infected areas where there is the
presence of data corrupted by malicious nodes. The
expansion can take place in peripheral area when one or more
infected node passing bogus information into another area.
 Local attacks: Attackers unleashed by malicious nodes
to neighboring nodes by sending false data in order to
change the status of evaluation and decision of victim
node. Such attacks can be very effective located in the
vicinity of one or more malignant nodes. The victim node
cannot make comparisons with other nodes in the
network; therefore unable to test the veracity of the
received data is valid.
 Remote attacks: Attackers are attacks to targets node
that is distant from the malicious node. The message
sending by attackers node contain the fake information, it
can arise conflict on a qualitative level between the
message and the received message by neighboring
nodes to a target node.
Fig.3: Attack with false information A2 and A3 disseminate
false information to influence network.
 Rational vs. evil: A malicious attacker does not seek
personal benefits from attacks that push into network.
This attack in the network does not consider the financial
benefits; in contrast to a rational attacker seeks personal
profit. To gain a personal profit, a rational attacker much
more predictable than a malicious attack in terms of goals
and objectives.
3.3 Classification of attacks according to the objectives
They may be also guided by well-defined objectives. The
objectives can be traffic control in a given area, the control of
vehicle movement, the induction to change the trajectory of
vehicles, blocking a service or even block all the services
offered by the VANET.
3.4 Classification of attacks based on Impact
The attacks may have different impacts depending on the
technique and technology that the attacker uses. The
classification according to the impact is as follows:
 Non Detected: Attack is not detected by the target nodes.
A target node cannot detect an attack if it is isolated or
completely surrounded by the malignant nodes. It
continuously transmits false information and a victim node
accepts incoming fake messages. But as soon as the
victim node is in the vicinity of an honest node, can re-
evaluate the integrity of the data receive so far and then
correct the message.
 Detected: Attack detected by the target nodes. A victim
node can detect an anomaly attack, because of the small
amount of available correct data, remains in doubt about
the contents of the receive data. This doubt remains until
it encounters a sufficient number of honest nodes that
provide a sufficient amount of information for a correction
of the data.
 Corrected: A node detects a malicious node due to the
data received from node that are in contradiction with the
data of observations by honest nodes. Some nodes have
the opportunity to correct the false messages, in addition
to identifying the malicious node.
4 VANET SECURITY CHALLENGES
VANETs will be the largest real-life instance of a self-
organized ad- hoc network if implemented correctly. Thus, its
size will be of millions of nodes that each has certain
properties and can be divided in categories: like authorities,
normal cars, service providers, attackers, etc. The main
problem for such a large-scale network is the scalability,
mostly because these types of problems should be solved
in a way transparent to the driver (the normal node in such a
network). Besides scalability issues, one of the most important
aspects that have to be taken in consideration is the dynamics
of such a network. Most of the important attacks target the
different forms of privacy that a normal user of the VANET [10]
and [11]. Thus, one of the major consumer concerns about
this type of communication is the potential influence on
privacy. People are usually skeptical about the exchange of
information from persons the already know, but from
strangers on a highway. Although there are solutions that can
offer the possibility of providing the driver and the vehicle
anonymity, this may negatively affect the liability of the
network. Another key element is a security system is trust [12].
This is particularly emphasized in vehicular networks because
of the high liability required from safety applications. Because
of the large number of independent network members and the
presence of human factor, it is highly probable that
misbehavior will arise. Another important factor is that

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consumers because highly concerned about their privacy [13].
Drives do not make an exception; therefore the level of trust
in vehicles as well as service providers will be low. Also,
besides driver and service providers there will be a
considerable presence of governmental authorities in such
network. Because of the skepticism of most members in such
network, the trust in these authorities will be only partial. Cost
is another important aspect in the deployment of inter-
vehicular communications . The first cost that we encounter in
the deployment of such network is the introduction of new
communication standards for vehicular communication that
will require manufacturers to install new hardware modules
on all vehicles, thus increasing the cost of the consumers.
Also, another cost is the one for the inter-vehicular
communication: mostly it the communication is based on
text messages through GSM service. Another important cost
is the permanent technical support for the hardware installed
on the roads. Last important cost is for the infrastructure
that will allow vehicles to access online authorities as part of
security services. The time span of inter-vehicular
communication until it reaches considerable penetration is
around a decade. This means that only a small proportion
of vehicles will contain the enhanced features of inter-
vehicular communication over the next couple of years.
The gradual deployment is an important factor that has to be
taken in consideration also from the security point of view.
5 SECURITY MECHANISM OF VANET
5.1 Requirement

A
uthe
nti
ca
ti
on
:
Vehicle reaction to events should be
based legitimate messages. Therefore we need to
authenticate the senders of the messages.

Verification
of d
ata consistency:
The legitimacy of
messages also encompasses their consistency with
similar ones, because the sender can be legitimate while
the message contains false data

Availability:
Even assuming a robust communication
channel, some attacks can bring down a network. It is
very important to point out that the network cannot be
brought down, and if the VANET is brought down it can be
restored through another way.

Privacy:
people are increasingly wary of “The Big
Brother Phenomenon” and also about the privacy of such
networks.
 R
ea
l
ti
me
constraints:
At the very high speeds
typical in VANETs, strict time constraints should be
respected Security Mechanism

Electronic
L
i
ce
n
s
e
Plates
(EL
P):
ELPs are unique
cryptographically verifiable numbers that will be used as
equivalents of traditional license plates. The advantage of
ELPs is that will automate the paper-based document
of checkup of vehicles. These types of license plate
maybe issued by governmental transportation authorities.
Hence, the authorities should have the cross- certification
agreements that will allow them to verify the ELPs issued
by the other authorities.
 Vehicular
P
K
I:
A public key infrastructure, also known as
PKI is the typical architecture used for networks where the
presence of online authorities is not always guaranteed.
Given the properties of large scale and initially low
penetration of vehicular communications infrastructure, a
PKI is a good choice for enabling inter-vehicular
communication [14]. There are some problems that
can occur while using this type of architecture, although it
seems very convenient for VANETs. The first problem is
the key distribution; another problem is the certificate
revocation by which the CA invalidates some
private/public keys pairs due to their discovery by an
attacker.
 Event data
r
eco
r
d
i
n
g
(EDR): Similar to the black
boxes on an airplane, EDRs will be used to in vehicles to
register all important parameters, especially in situation
like accidents
 Tamper proof
h
a
r
dw
a
r
e
: Vehicles will store
cryptographic material such as ELPs and VPKI private or
public keys in tamper-proof hardware that will keep this
material safe from attackers, thus decreasing the
possibility of information leakage.
 Data
co
rr
e
l
a
ti
o
n
:
The bogus information attack cannot
be easily discovered, like other attacks like DoS ones. The
main solution to this problem is to use data correlation
techniques that will collect data received from different
sources and thus allowing the vehicle to make a decision
on the level of credibility, consistency and relevance of
the received information.

Sec
u
r
e
p
o
s
iti
o
n
i
n
g
: There is a real need for secure
position verification, thus vehicles or base-stations may
want to verify the position of other vehicles or base-
stations “on the fly”. The most common solution for this
issue is the GPS system that is very convenient but also
has a lot of security leaks.
5.2 Privacy and Authentication:
Drawing from the analogy with existing administrative
processes and automotive authorities a large number of
certificate authorities (CAs) will exist. Each of them is
responsible for the identity management of all vehicles
registered in its region. The deployment of secure
vehicular communication is also influenced by the hierarchical
structure within each CA and cross-certification among CA
(secure vehicular communication could still be handled
locally to a great extent). At the same time, vehicles registered
with different CAs can communicate securely in the network as
soon as they validate the certificate of one CA on the public
key of another CA. The deployment of such networks
emphasize that CA manages long- term identities, credentials
and cryptographic keys for
ve
hi
cl
e
s
.
As a basic guideline
that can be found in [15], processes and policies for
privacy protection should be defined, with minimum
private information disclosure on a need-basis and fine-
grained control mechanisms for regulating private information
disclosure. Nonetheless, signed messages can be trivially
linked to the certificate of the signing mode: thus, the
removal of all information identifying the user from node
certificate does make communication anonymous[16]. Yet, as

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the vehicle can change pseudonyms, linking messages
signed under different pseudonyms becomes increasingly
difficult over time. The change of a pseudonym should be
accompanied by a change of the node identifiers used by
underlying networking protocols.
Fig.4:
Security Mechanism of VANET
If such identifiers do not change along with the pseudonym,
messages generated but a node could be trivially linked
according to the address used by the node's hardware and
software
.
On the other hand, the network operation may
require that node identifiers remain unchanged for a specific
period of time. This implies that a change of pseudonym
would be ineffective and thus meaningless throughout the
period a protocol identifier must remain changed.
5.3 Security Analysis
Authentication of message legitimacy is provided by the
digital signature of the sender and the corresponding CA
certificate. The only guarantee that this provides is that
the message comes from a vehicle that was trusted, at least
when the keys were issued. Availability can be totally
guaranteed. Even though the availability of vehicles and the
network is almost totally guaranteed, the ways in which an
attacker can disrupt the network service are limited: outsiders
can only mount jamming attacks. Starting from the initial
assumptions we have the following facts: Vehicles cannot
claim to be other vehicles since they only interact with their
anonymous public keys vehicles cannot cheat about their
position and related parameters if a secure positioning solution
is used a vehicle cannot deny having sent a message because
it is signed by an anonymous key that belongs exclusively to
the sender
.
Using these facts, the security of a VANET is more
a certainty than an assumption. Yet, many problems can
occur when trying to solve the basic issues of security in IVC.
In order to preserve the driver's anonymity and minimize the
storage costs of public keys, a key changing algorithm that
adapts to the vehicle speed can be propose. Also the
algorithm takes into account key correlation by the attacker
.
On one hand the anonymous key set size should be small to
reduce storage space on vehicles, but also on the other hand
the certificate lifetime should be short to reduce the
vulnerability window of the system if an anonymous public or
private key is compromised. Therefore, a tradeoff must be
made between the two. The life time certificate uses the
following aspects: each anonymous key should be used only
with a sequence of consecutive messages. Also, the lifetime
certificate should be short, around one day, to limit in the
effects of a possible key compromise. On the other hand,
driving duration changes from day to day, hence some days a
larger number of keys may be required. To account for
this, the lifetime certificate should be stretched over
several days. Another important aspect that has to be taken in
consideration is that a vehicle should change its anonymous
key only after having used it for a certain number of
messages. As we propose using a PKI for supporting security
in VANETs, it is important to choose a Public Key
Cryptosystem (PCKS) with an acceptable duration overhead in
vehicular context like the following: RSA sign: the key and
signature sizes are large (256 bytes).
ECC (Elliptic Curve Cryptography): it is more compact that
RSA (28 bytes), faster in signing but slower in verification.
NTRU Sign (a recent cryptosystem) the key size is of
approximately 197 bytes, but it is much faster than both in
both signing and verification.
4 CONCLUSION
The security of VANET of the road condition information
transferring system is crucial. For example, it is essential to
make sure that life-critical information cannot be inserted or
modified by an attacker. The system should be able to help
establish the liability of drivers; but at the same time, it should
protect as far as possible the privacy of the drivers and
passengers. In fact, there are very few academic publications
describing the security architecture of VANETs. So integrate
the characteristics of ad hoc network itself, in the ITS of this
paper, we concern the security issues of VANETs from only a
few aspects based on some referential papers and provide the
appropriate solving measures.
REFERENCES
[1] G. Samara, et al., "Security issues and challenges of
Vehicular Ad Hoc Networks (VANET)," in 4th International
Conference on New Trends in Information Science and
Service Science (NISS), 2010, pp. 393-398.
[2] B. K. Chaurasia, et al., "Attacks on Anonymity in VANET,"
in International Conference on Computational Intelligence
and Communication Networks (CICN), 2011, pp. 217-221.
[3] G. Samara, et al., "Security Analysis of Vehicular Ad Hoc
Networks (VANET)," in Second International Conference
on Network Applications Protocols and Services
(NETAPPS), 2010, pp. 55-60
[4] M. Burmester, et al., "Strengthening Privacy Protection in
VANETs," in IEEE International Conference on Wireless
and Mobile Computing Networking and Communications,
WIMOB '08., 2008, pp. 508-513.
[5] Chim, TW, Yiu, SM, “SPECS: Secure and Privacy
Enhancing
Communications Schemes for VANETs,” Ad
Hoc Networks, Volume 9, Issue 2, March 2011, pp. 189-
203.

INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 2, ISSUE 4, APRIL 2013 ISSN 2277-8616
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IJSTR©2013
www.ijstr.org
[6] F. Kargl, P. Papadimitratos, L. Buttyan, M. Müter, E.
Schoch, B. Wiedersheim, Ta-Vinh Thong, G. Calandriello,
A. Held, A. Kung, J.-P. Hubaux, Secure vehicular
communication systems: implementation, performance,
and research challenges, IEEE Communications
Magazine, vol. 46, no. 11, pp. 110-118, November 2008
[7] S. Tsugawa, "Issues and Recent Trends in Vehicle Safety
Communications Systems" IATSS Research, Vol.29,
No.1pp.7-15(2005.2)
[8] P. Golle, D. Greene, “Detecting and Correcting Malicious
Data in VANETs”. In Proceedings of the First ACM
Workshop on Vehicular Ad Hoc Networks, pp. 29-37,
2004.
[9] N. Sastry, U. Shankar and D. Wagner. “Secure
Verification of Location Claims”. In ACM Workshop on
Wireless Security. WiSe 2003.
[10] M. Raya, P. Papadimitratos, and J.-P. Hubaux, Securing
Vehicular Communications, In IEEE Wireless
Communications Magazine, Special Issue on Inter-
Vehicular Communications, October 2006
[11] M. Raya and J.-P. Hubaux, Security Aspects of Inter-
Vehicle Communications, In Proceedings of STRC 2005
(Swiss Transport Research Conference), March 2005
[12] P. Papadimitratos, V. Gligor, and J.-P. Hubaux. Securing
Vehicular Communications - Assumptions, Requirements,
and Principles, In Proceedings of the Workshop on
Embedded Security in Cars (ESCAR) 2006, November
2006.
[13] V. Paruchuri, "Inter-vehicular communications: Security
and reliability issues," in International Conference on ICT
Convergence (ICTC), , 2011, pp. 737-741.
[14] A. Wasef, et al., "Complementing public key infrastructure
to secure vehicular ad hoc networks [Security and Privacy
in Emerging Wireless Networks]," IEEE Wireless
Communications, vol. 17, pp. 22-28, 2010.
[15] P. Papadimitratos, L. Buttyan, T. Holczer, E. Schoch, J.
Freudiger, M. Raya, Z. Ma, F. Kargl, A. Kung, J.-P.
Hubaux, Secure vehicular communications: design and
architecture, IEEE Communications Magazine, vol. 46, no.
11, pp. 100-109, November 2008
[16] J. Freudiger, M. Raya, M. Félegyházi, P. Papadimitratos,
and J.-P. Hubaux, Mix-Zones for Location Privacy in
Vehicular Networks, In Proceedings of WiN-ITS, August
2007