jected massive packets to exhaust the resources of no-
des, save, ed it, and then re-transmit packets as if they
had been sent by a user legitimate. In ad- hoc net-
works there are some very sophisticated attacks, such
as the wormhole attack, can only be co mmitted by
compromised nodes and are hard to avoid. The use of
cryptography does not solve the problem of these no-
des compromised by a simple authentication because
these nodes are legitimate participants in the routing
process prior to being controlled by the attacker, so
we have to especially considering other solutions to
this problem like detection approaches.
An Intrusion Detection System (IDS) is a mecha-
nism tha t monito rs a network or systems to identify
abnormal or suspicious activities. It allows having in-
formation of failed or successful intrusions attempts.
Solutions are proposed by IDS for detecting internal
attacks. In order to minimize the im pact of malicious
vehicles, VANETs demand the IDS that is capable of
detecting attacks that have broken down the network.
In order to ensure their nor mal operation, VANETs
will be able to respond and isolate the intruders using
the IDS system. But bef ore the IDS c an be applied to
the VANETs practically, there is a primary issue that
has to be solved is how to select the profitable a nd
optimal detection strategy.
Game theory is a mathematical tool that studie s
situations of conflict and cooperation between se-
veral involved players. It has been widely applied in
the field of network security, preventing DoS attac k
(Mohi et a l., 2 009), and intrusion detectio n (Reddy,
2009). When a game in a system with incomplete
informa tion has many stages, the sig naling game in
which the posterior probability can be updated dyn-
amically is always considered to model the system.
Briefly, the signaling game is a dynamic gam e that
studies the situation of incomplete inf ormation and
involving two players: the first one (called th e Sen-
der) is infor med and the second one (called the Re-
ceiver) is not. The strategy set of the Sender consists
of actio ns c ontingen t on its type while the strategy set
of the Receiver consists of actions con tingent on the
Sender’s ac tions. Generally, in a signaling game, the
Sender has a private information while the Receiver
has a common inf ormation.
The intrusion detection in VANETs can be mo-
deled as a signaling game. Gener ally, a classic IDS
for guaranteeing VA NET security is compo sed of the
monitor and decision modules. The monitor module
aims to check the VANE T events while the decision
module aims to dec ide whether an event is normal or
not. This dyna mic situation is an interac tion between
malicious vehicle nodes and the IDS that is designed
and implemented to make VANETs secure. Sig na-
ling game is considered as a tool that is very profita-
ble to depict the characteristic of interactive situations
above. This approach can ac hieve the consequence
of selecting the Defend strategy optimally, which will
improve IDS’ real positive outcomes.
In this paper, our work focused on the signaling
game approach to study and ana lyze the interacti-
ons between a malicious vehicle node and a CH-
IDS agent in VAN ETs. We set up th e distributed-
centralized network model, in which each vehicle has
been equipped with an IDS agent. Not all IDS agents,
but only the IDS a gent in coalition head (CH-IDS)
will launch to to reduce channel contention and pac-
ket collisions.
The rest of this pa per is organized as follows.
Section II presents related work based on the IDS’
solutions in VANETs. The Intrusion Detection G a me
model, the stage Intrusion Detection Game, its pure
and mixed strategy BNE are introd uced in Section III.
Finally, Section IV concludes this work.
2 RELATED WORK
The security issues on VANETs have become one of
the primary concerns. Because of the high no des mo-
bility, the shared wireless medium and the absence
of centralized security services in VANET, it is in -
herently very vulnerable to attacks than wired net-
work. Cryptographic solutions, can be used as the
first line of defense for redu cing the possibilities of
attacks. However, these techniq ues have limited pre-
vention and a re not efficient in gen e ral, and th ey are
designed for a set of previously known attacks. They
are unlikely to avoid most recent malicious attacks.
For this reason, there is a need of another technique
to “detect and notify” these newer attacks, i.e . “intru-
sion detection”. This section aims to present a cur-
rent techniques of Intrusion Detection System (IDS)
aware wireless networks. In (Pattnaik a nd Pattana-
yak, 2014), the authors have focused on some cha-
racteristics of VANETs with possible types of attacks
based on intrusion detection. Also they have discus-
sed the most suitable IDS techn ique like watchdog
with their effect in VANETs. The applica tion of VA-
NETs is a rising technolo gy which can provide the fu-
ture directions of research in vehicular environment.
In (Sen, 2010), th e authors have proposed a cluster-
based semi-centralized ap proach that integrates a lo-
cal intrusion detection in a node or in a cluster. In
the network architecture pr oposed in th is work, the
nodes are grouped into clusters which are monitored
by cluster head while the inter-cluster communication
takes place thro ugh gateways by using mobile agents