2. Please Cite this Article at: R.Kirubaburi et al, Journal of Current Engineering Research, 3 (3),May-June 2013, 1-7
2
1. non selfish nodes,
2. partially selfish nodes,
3. fully selfish nodes.
1.2.1 Reputation based technique
In reputation based technique each node
monitors the transmission of a neighbor node. Each
node in the networks runs the confidant protocol. If the
neighbor nodes does not relay the packet correctly it is
considered as a selfish nodes. Monitoring the nodes
transmissions by overhearing the channel is not energy-
efficient for transmitters. The extreme power
transmission is used instead of adapting the
transmission power according to the distance separating
the transmitter and the receiver to enable more
neighboring nodes to overhear the packet transmission.
In the reputation system maintains a list containing the
selfish nodes. When forwarding packets, nodes avoid
next nodes on the list. Finally it will drops the request
from selfish nodes. In reputation mechanism use the
more power consumption other than any method. Each
node will loss the energy frequently as they monitoring
the networks. There are two technique is used in the
reputation based technique they are
i. Watchdog Technique.
ii. Pathrater Technique.
i. Watchdog Technique
The Watchdog is one of the mechanisms which
detect selfish nodes by running a misbehaving node
locator on every host that maintains a buffer of recently
sent packets. If the count exceeds a threshold value, the
watchdog considers that host as a misbehaving
node[14].
ii. Pathrater Technique
A Pathrater is a mechanism which maintains a
rating for every other host in the network. To choose a
route that is considered to be reliable, it calculates a
path metric by averaging the rating of the nodes on the
paths and chooses the path with the highest metric. If
any node gets very low rating, it should be considered
as a selfish node and thus excludes them from
routing[14].
1.2.2 Credit-payment technique (incentive
mechanisms)
Butty´an and Hubaux proposed incentives to
cooperate by means of so-called nuglets that serve as a
per-hop payment in every packet in a secure module in
each node to support forwarding. The secure module is
required to ensure the correct number of nuglets is
withdrawn or deposited. They propose two technique
for payment of packet forwarding, the Packet Purse
Model and the Packet Trade Model. In the Packet Purse
Model the sender pays and thus loads the packet with a
number of nuglets. Each intermediate node takes one
nuglet when it forwards the packet. If there are no
nuglets left at an intermediate node, the packet is
dropped. If there are nuglets left in the packet once it
reaches the destination, the nuglets are lost. In the
Packet Trade Model, the destination pays for the packet.
Each intermediate node buys a packet from the previous
hop and sells it to the next for more nuglets.
1.2.3 Game theory based technique
Selfish nodes are sometimes called as freeloaders
getting resources from the network and did not upload
any resources to the network. Minimising the effects of
freeloaders require the services of some external
centralized authority. The inclusion of third party
produces overhead in tracking, storing and processing
the behaviour of other nodes. The behavior of selfish
user depends on the game rule of the games. The
mechanisms design in game theory is to design
appropriate game rule that leads to desirable outcome
which is cooperatively relay of packets in networks.
2. RELATED WORK
Tamper-Proof Device (TPD)-based incentive
mechanism used to manage the credits. The packet
purse and the packet trade models have been used. In
the packet purse model, only the source node pays by
loading some credits in each packet before sending it.
Each intermediate node acquires the amount of credits
that cover the packet’s relaying cost. In the packet trade
model, each intermediate node runs an auction to sell
the packets to the following node in the route. In this
way, each intermediate node earns some credits and the
destination node pays the total packet relaying cost[4].
In Sprite, a simple, cheat-proof, credit based system for
stimulating cooperation among selfish nodes in mobile
ad hoc networks. Our system provides incentive for
mobile nodes to cooperate and report actions honestly.
payments and charges from a game-theoretic
perspective, and they showed that system motivates
each node to report its behavior honestly, even when a
collection of the selfish nodes colludes[16].
In MODSPIRITE system detects selfish node using
neighbor monitoring mechanism and enforce
cooperation among non cooperative node by providing
incentives to intermediate nodes. The architecture of
MODSPIRITE system contains several nodes and a
cluster head. All other nodes communicate with cluster
head and give receipt of forwarding data packet. Cluster
head selection criteria can base on ID, degree, residual
energy, low mobility and association with other nodes.
If data correctly reaches the destination, no credit is lost
or earned by the sender and intermediate nodes
respectively. If the data does not reach the destination, it
indicates that one of the intermediate nodes acts as a
selfish node and this selfishness is detected by Neighbor
Monitoring Mechanism[2].
In RISE, a Receipt-free Incentive SchEme, for MWNs.
The nodes submit lightweight payment reports
containing their alleged charges and rewards to the AC
to clear the payment, and store undeniable security
3. Please Cite this Article at: R.Kirubaburi et al, Journal of Current Engineering Research, 3 (3),May-June 2013, 1-7
3
tokens called evidences. The fair reports can be cleared
with almost no processing overhead. For the cheating
reports, the evidences are requested to identify the
cheating nodes and exclude them. Since cheating is
exceptional, RISE can significantly reduce the overhead
of processing and submitting the payment data
compared to the receipt-based schemes while achieving
the same security strength. Our analysis and simulations
demonstrate that RISE can secure the payment and clear
the payment with almost no processing overhead. For
the cheating reports, our scheme requests the evidences
to identify and evict the cheating nodes[3].
In FESCIM, a Fair, Efficient, and Secure Cooperation
Incentive Mechanism, to stimulate the node cooperation
in MCN. In order to efficiently and securely charge the
source and destination nodes, the lightweight hashing
operations are used in the ACK packets to reduce the
number of the public-key-cryptography operations. The
destination node generates a hash chain and signs its
root, and acknowledges message reception by releasing
a hash value from the hash chain. In this way, the
destination node generates a signature per a group of
messages instead of generating a signature per message.
Moreover, to reduce the overhead of the payment
cheques, one small-size cheque is generated per session
instead of generating a cheque per message, and
Probabilistic cheque submission scheme has been
proposed to reduce the number of submitted cheques
and protect against the collusion attack[1].
3. SYSTEM ARCHITECTURE
3.a Architecture of MWN
3.b Accounting Center
4. PROPOSED SYSTEM
4.1 Route Discovery Phase
All communications are unicast and the nodes
can communicate in both modes: pure ad hoc or hybrid.
The source node’s messages may be relayed in several
hops by the intermediate nodes to the destination node.
The source node transmits its messages to the source
base station (BSS), if necessary in multiple hops. If the
destination node resides in a different cell, the messages
are forwarded to the destination base station (BSD) that
transmits the messages to the destination node possibly
in multiple hops. In an ad-hoc network communication
between two nodes beyond the transmission range relies
on intermediate nodes to forward the packet. The
communication takes place using routing protocol
On demand routing protocol is designed to restrict the
bandwidth consumed by control packets in wireless
networks. Here DSR is used, which is a source routing
protocol and this protocol can react to topological
changes rapidly. DSR is a reactive routing protocol. In
order to establish the end-to-end routing communication
between nodes we are using DSR routing protocol.
There are two main operations in DSR. They are route
discovery and route maintenance. Each node gathers
information about the network topology by overhearing
other nodes’ transmissions. This is known as
indiscriminate mode of operation. Each node maintains
a route cache to remember routes that it has learnt about.
All of the routing protocols including DSR assume that
all nodes in the network are cooperative and forward
others’ messages.
In route discovery phase, the route request packet is
flooded in networks each node in network after
receiving the route request packet, it will rebroadcast the
packet to neighboring nodes. Route request packet
consist of sequence number generated by source nodes
and path it has traversed. A sequence number on packet
is used to prevent loop formation and to avoid multiple
transmission of same route request by intermediate node
and receives it through multiple paths. After receiving
the first route request from source nodes, the destination
nodes replies through reverse path to source nodes. In
pure adhoc mode the source and destination nodes
communicate without any base station and in hybrid
4. Please Cite this Article at: R.Kirubaburi et al, Journal of Current Engineering Research, 3 (3),May-June 2013, 1-7
4
mode as a minimum of one base station is required for
communications.
4.2 Data Transmission and Relay Phase
In this phase source node select the shortest
path to the destination nodes based on number of hop
count in the different ways to reach the destination.
Route reply packet contain session identifier with
destination node signature. The session identifier contain
the identities of the nodes in the route. The source nodes
attaches its certificate to all the data packet to enable the
intermediate and destination nodes to verify the
signature. Each data packet is encrypted using hashing
function with signed signature from source nodes. Every
packet is hashed before it transmitted to neighbor nodes.
Before relaying each intermediate nodes verifies
signature to ensure its integrity and authenticity. Each
data packet has unique number for identification. Each
node the route restarts a timer each time the node
transmit a packet. The route is considered broken when
the time expires. After receiving the acknowledgement
of the last message the source nodes sends end-of-
session packet to close the session. The Source Node
will calculate the RRT (Round Trip Time) of each node
when they packet relayed to destination nodes. The RRT
is used to calculate the trust value of each nodes during
data transmission and which is used to find most trusted
nodes to submit the cheques to accounting center.
4.3 Cheque Composition Phase
In this phase source nodes, destination nodes and
intermediate nodes submit cheques to Accounting
center. The cheque contain descriptor and digital
certificate. The descriptor shows the hashed value of the
message and its unique number. The digital certificate
shows the hashed signature of node identity. The source
node cheque consist of hashed value of last sent data
packet and source and destination node signature. The
destination node cheque consist of hashed value of last
received data packet and source & destination node
signatures. The source node sending token to any one
of the intermediate node that will submit cheque to AC.
Cheques are transmitted to AC once per route.
For each route one cheque containing the data
for all the intermediate nodes can be composed. A
cheque contains two main parts: Descriptor (D) and
Security Token (St). The Descriptor contains Si that has
the identities of the data transmitted and the data
delivered, and TS,. The Descriptor also contains the
messages’number (X), the hash value of the last
received message, the hash chains’ roots and seeds, and
the last released hash value . The Security Token is an
undeniable proof that prevents repudiation and
manipulation, and thus ensures that the cheque is
undeniable, unmodifiable, and unforgeable. In order to
significantly reduce the cheque size, the Security Token
is composed by hashing the source and destination
nodes’ signatures instead of attaching the large-size
signatures. The base station submits the cheque to the
AC for redemption, but the nodes submit the cheque if
the base station belongs to a different operator. The
nodes also submit the cheque if the route is not
complete, i.e., the EOS packet is not received, and the
base station does not have correct information. Finally,
the AC clears the cheque according to the charging and
rewarding policy.
4.3.1 Token based cheque submission
Moreover reducing the overhead of payment
cheques by all intermediate nodes, the token based
cheque submission scheme is proposed. In token based
cheque submission scheme is used to avoid collusion
attacks and reducing the number of cheques sent to
accounting center by all intermediate node at same time.
Token is consist of identities of intermediate nodes,
signature of source and destination nodes and also
contain which intermediate node to possess the token.
The node which have token allowed to send cheque to
accounting center. Source node selects the intermediate
node based on their high credits and trusted value and
send token to that particular intermediate node. Based
on token based scheme the cheque is composed by
intermediate nodes. Trust value is estimated by Trusted
RTT algorithm.
Trusted RTT algorithm
BEGIN;
N, n ≠ 0; // N→Maximum Capacity of network //
n ≤ N; // n→ No. of nodes in routing //
T ϵ n; // T→ trust value //
If (n = = Ack) // if source node receives
acknowledgement //
Set the timer;
else if (n≤ RTT) // Round Trip Time (RTT) //
n++ ; // Increment the trust value //
else if (n ≥ RTT)
n- - ; // Decrement the trust value //
else
node selects next neighbor node to send packets;
END;
4.3.1.1 Round-Trip Time (RTT)
Round-Trip Delay time (RTD) or Round-Trip
Time (RTT) is the length of time it takes for a packet to
be sent plus the length of time it takes for an
acknowledgment of that packet to be received. This
time delay therefore consists of the transmission times
between the two points of a signal. In this Trusted RTT
algorithm starts when number of nodes is less than the
capacity of network. Trust value is belong to routing
nodes. Until the node received with the
acknowledgement, it will compare the response time of
node with Round Trip Time. RTT value is greater than
node response time the node is trusted else the node is
less trusted. The RTT was originally estimated in TCP
by
RTT = (α · Old_RTT) + ((1 − α) ·
New_Round_Trip_Sample)
Where α is constant weighting factor(0 ≤ α < 1).
Choosing a value α close to 1 makes the weighted
average immune to changes that last a short time (e.g., a
single segment that encounters long delay). Choosing a
5. Please Cite this Article at: R.Kirubaburi et al, Journal of Current Engineering Research, 3 (3),May-June 2013, 1-7
5
value for α close to 0 makes the weighted average
respond to changes in delay very quickly. This was
improved by the Jacobson/Karels algorithm, which
takes standard deviation into account as well.
The Source node calculate the trust value of each
intermediate node on routing based on Trusted RTT
algorithm. The intermediate node response time is less
than or equal to RTT (Round Trip Time) are considered
as trusted node. If the time it takes for an
acknowledgment of that packet to be received is higher
than RTT value that it is considered as less trusted
nodes. The trusted node will get the token from source
node and send cheque to accounting center. The source
node selects the intermediate node, to send token to that
node based on their high trust value and high credits.
4.4 Cheque Clearance Phase
In this phase the cheques are evaluated and
credited in node’s account by accounting center. The
accounting center will have some components. They are
classifier, eviction, credit update and trust monitor. The
classifier will check the cheque that is previously
deposited to accounting center and it will classify the
source, destination node and intermediate nodes
cheques. After classification of cheques that will be sent
to eviction process. In eviction process each cheque is
validated by their hashed signatures. Cheque is valid if
the resultant hash value is identical to cheque. If the
given cheque is correct it will credit the node account
increase the trustworthy of node in AC, if the given
cheque is invalid the accounting center will not credit
the node account and decrease the trustworthy in node
account. Trust monitor is used to analyses the node
performance and their trusted values and nodes credit
accounts. Trust monitor will remove the low trusted
node from future data transmission from network based
on their past activities. The source and destination nodes
will be credited for every transmitted messages even if
does not reach the destination but intermediate nodes
rewards only for delivered messages. Here the trust
value of nodes calculated by Source Node during data
transmission will be finally sent to Accounting Center
and these values are updated in trustworthy monitor will
used for future analysis of nodes in routing . The trust
update for node trust value is updated by aggregating its
session rating with its old trust value. Moreover, a node
is identified as malicious when it spends consecutive
sessions in the suspicious state because the node receives
negative ratings more than the normal rate. A node is
also identified as malicious when the difference between
the spent times in the honest and the suspicious states is
less than β because the node receives positive ratings
less than the normal rate. The payment clearance and
trust update delay is the elapsed time from a session’s
occurrence until the payment is cleared and the trust
values are updated. AC provides certificate with unique
identity for each nodes in the networks.
5. SECURITY ANALYSIS
Since the mobile nodes are autonomous and
self-interested, the attacker has full control on his node,
and thus he can change its operation. The hackers work
individually or collude with each other under the
control of one authority to launch sophisticated attacks.
The attackers are rational in the sense that they
misbehave when they can achieve more benefits than
behaving honestly. Specifically, the attackers attempt to
steal credits, pay less, and communicate freely. Since
each node in an Ad-hoc network is constrained by
limited energy, bandwidth and computational resources,
a node may not be willing to forward packets that are
not directly beneficial to it or node attack on routing
protocol to disrupt network performance. Such nodes
are known as Non-cooperative or misbehaving nodes.
Some Common Attacks in Multi-Hop Wireless
Networks
Filtering Attack – In this type of attack, the adversary
can observe and modify both the input and the output of
each device he controls, but he cannot extract the secret
information from these devices.
Collusion Attack – Attackers may work together to
improve their attacking ability.
False Rumour – In false rumor misbehavior, a node
floods the false and negative information regarding
other nodes by claiming that they are misbehaving but
actually they are not.
Collusion Attack – In this attack, two or more nodes
collude in order to influence the reputation rating. Here
a node can recommend others node as cooperative or
can give negative information of cooperative node.
Double-Rewarding attack – The attacker attempts to
illegally increase its rewards by submitting a check
multiple times.
Double-Spending attack – The attacker attempts to
generate identical checks for different sessions to pay
once. Two checks cannot have the same identifier
because it contains the identities of the session nodes
and time stamp.
Free-Riding attacks – Two colluding intermediate
nodes in a legitimate session manipulate the session
packets to piggyback their data to communicate freely.
Impersonation attack – The attackers attempt to
impersonate other nodes to communicate freely or steal
credits.
Denial of Service – Attackers cause denial of service by
preventing the calculation and dissemination of
reputation values.
6. Please Cite this Article at: R.Kirubaburi et al, Journal of Current Engineering Research, 3 (3),May-June 2013, 1-7
6
6. RESULTS & DISCUSSION
The Main aim is to thwart the selfishness attack and
collusion attacks multi-hop wireless networks. In order
to prevent cheque submission collusion attacks we
using a token based cheque submission method. In this
method, node which posses the token which is allowed
to send cheque to accounting center. Source node
which is responsible for the generating token and select
the any of intermediate node in the routing network.
More number cheques is reduced effectively when
compared to existing systems. Trustworthy nodes of
each nodes in routing is monitored by accounting
center , so that the untrusted nodes are removed from
future communications.
Finally, which is used to indentify irrational and
malicious nodes in the networks and this method solves
the several attacks in Multi-hop Cellular Networks.
Impersonation Attack is not possible because the nodes
use their private keys to sign the packets, and the
attackers cannot compute other nodes’ private keys.
Free Riding Attacks is thwarted by, the integrity of the
packets should be checked at each node, and thus, the
first node after the first colluder can detect the packet
manipulation and drop the packet. DOS Attack is
thwarted by token based submission scheme. Incentives
Mechanism is used to prevent the nodes from selfish
behavior. Incentives are used to compensate for nodes
to cooperation in networks.
7. CONCLUSION
Multi-hop Wireless Networks exhibits new
vulnerabilities to malicious attackers and denial of node
cooperation. The attackers collude with each other to
launch sophisticated attacks. The proposed token based
cheque submission scheme to reduce the overhead of
the payment cheques to accounting center and thwart
the collusion attacks. Overall cheque submission to AC
by all the participating nodes routing is reduced by
instead of submitting all intermediate node, the source
node will select any one of the high trusted intermediate
node submit cheques to AC to update credits of routing
nodes based on their high credit and trusted value.
Usually the nodes in the network have some default
credits then only they able to participate in the routing.
Trust value is calculated of each node by Trusted
RTT( round trip time). Token possessed node only able
to send cheque to accounting center. Trustworthy
checker in Accounting center will precisely differentiate
the honest nodes and irrational packet droppers and
remove the selfish nodes from networks. Cheques are
generated per session instead of generating per
messages. Finally we have significantly reduced the
overhead of storing, submitting and processing of
cheques in nodes and accounting center of the multi-
hop wireless networks.
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2
1. non selfish nodes,
2. partially selfish nodes,
3. fully selfish nodes.
1.2.1 Reputation based technique
In reputation based technique each node
monitors the transmission of a neighbor node. Each
node in the networks runs the confidant protocol. If the
neighbor nodes does not relay the packet correctly it is
considered as a selfish nodes. Monitoring the nodes
transmissions by overhearing the channel is not energy-
efficient for transmitters. The extreme power
transmission is used instead of adapting the
transmission power according to the distance separating
the transmitter and the receiver to enable more
neighboring nodes to overhear the packet transmission.
In the reputation system maintains a list containing the
selfish nodes. When forwarding packets, nodes avoid
next nodes on the list. Finally it will drops the request
from selfish nodes. In reputation mechanism use the
more power consumption other than any method. Each
node will loss the energy frequently as they monitoring
the networks. There are two technique is used in the
reputation based technique they are
i. Watchdog Technique.
ii. Pathrater Technique.
i. Watchdog Technique
The Watchdog is one of the mechanisms which
detect selfish nodes by running a misbehaving node
locator on every host that maintains a buffer of recently
sent packets. If the count exceeds a threshold value, the
watchdog considers that host as a misbehaving
node[14].
ii. Pathrater Technique
A Pathrater is a mechanism which maintains a
rating for every other host in the network. To choose a
route that is considered to be reliable, it calculates a
path metric by averaging the rating of the nodes on the
paths and chooses the path with the highest metric. If
any node gets very low rating, it should be considered
as a selfish node and thus excludes them from
routing[14].
1.2.2 Credit-payment technique (incentive
mechanisms)
Butty´an and Hubaux proposed incentives to
cooperate by means of so-called nuglets that serve as a
per-hop payment in every packet in a secure module in
each node to support forwarding. The secure module is
required to ensure the correct number of nuglets is
withdrawn or deposited. They propose two technique
for payment of packet forwarding, the Packet Purse
Model and the Packet Trade Model. In the Packet Purse
Model the sender pays and thus loads the packet with a
number of nuglets. Each intermediate node takes one
nuglet when it forwards the packet. If there are no
nuglets left at an intermediate node, the packet is
dropped. If there are nuglets left in the packet once it
reaches the destination, the nuglets are lost. In the
Packet Trade Model, the destination pays for the packet.
Each intermediate node buys a packet from the previous
hop and sells it to the next for more nuglets.
1.2.3 Game theory based technique
Selfish nodes are sometimes called as freeloaders
getting resources from the network and did not upload
any resources to the network. Minimising the effects of
freeloaders require the services of some external
centralized authority. The inclusion of third party
produces overhead in tracking, storing and processing
the behaviour of other nodes. The behavior of selfish
user depends on the game rule of the games. The
mechanisms design in game theory is to design
appropriate game rule that leads to desirable outcome
which is cooperatively relay of packets in networks.
2. RELATED WORK
Tamper-Proof Device (TPD)-based incentive
mechanism used to manage the credits. The packet
purse and the packet trade models have been used. In
the packet purse model, only the source node pays by
loading some credits in each packet before sending it.
Each intermediate node acquires the amount of credits
that cover the packet’s relaying cost. In the packet trade
model, each intermediate node runs an auction to sell
the packets to the following node in the route. In this
way, each intermediate node earns some credits and the
destination node pays the total packet relaying cost[4].
In Sprite, a simple, cheat-proof, credit based system for
stimulating cooperation among selfish nodes in mobile
ad hoc networks. Our system provides incentive for
mobile nodes to cooperate and report actions honestly.
payments and charges from a game-theoretic
perspective, and they showed that system motivates
each node to report its behavior honestly, even when a
collection of the selfish nodes colludes[16].
In MODSPIRITE system detects selfish node using
neighbor monitoring mechanism and enforce
cooperation among non cooperative node by providing
incentives to intermediate nodes. The architecture of
MODSPIRITE system contains several nodes and a
cluster head. All other nodes communicate with cluster
head and give receipt of forwarding data packet. Cluster
head selection criteria can base on ID, degree, residual
energy, low mobility and association with other nodes.
If data correctly reaches the destination, no credit is lost
or earned by the sender and intermediate nodes
respectively. If the data does not reach the destination, it
indicates that one of the intermediate nodes acts as a
selfish node and this selfishness is detected by Neighbor
Monitoring Mechanism[2].
In RISE, a Receipt-free Incentive SchEme, for MWNs.
The nodes submit lightweight payment reports
containing their alleged charges and rewards to the AC
to clear the payment, and store undeniable security](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)