Veronica EyoSharvari Joshi

• The nodes are left unattended• An Adversary can physically compromise the

nodes

Solution?Solution? Authentication and cryptographic mechanisms

alone can not solve this problem

The trust system was used for security in the Wireless sensor network

These systems identify malicious nodes, computes a trust rating of the node and exclude the nodes from the network.

First trust based model designed and developed for sensor networks.

It makes use of the watchdog mechanism to collect data and monitor different events going on in the node, to build reputation(Rij)of the node and then get the trust rating (Tij)of the node.

Tij = Pj + 1

Pj + Nj + 2

Pj = Positive outcome Nj = Negative outcome

RFSN can not distinguish between negative and positive events in the node.

• Addressed the uncertainty issue but still cooperated with the malicious nodes.

• Has one value of trust rating for different events.

• Event based trust framework is proposed to detect malicious sensor nodes

• A new protocol ESTN is developed• A new direction in trust system for wireless

sensor network is proposed

The trust rating is dependent on different events in the node

Each event on the sensor node has a different trust rating

A sensor node has several trust ratings stored in its neighbor nodes

The agent node

Classifies all the events and then builds a reputation table of the nodes

A trust table is then computed from the reputation table and broadcast to all the nodes.

Event E happened in sensor nodes. Let E={e1 ,e2 ,e3 ,....en }

Event function. F={F(ei )| ∀ei ∈E,F(ei) ≥1,F(ei )∈N}

Positive outcome pi

Negative outcome ni

<p ,n > is binary event for a certain event ei of sensor node.

Define reputation space of event ei

RS(ei )={<pi ,ni>|ti=pi+ni;pi=F(ei ) or ni=F(ei ) ∀ei∈E}

P<pi ni> (x)= (pi+ni+1)! Xi ^(pi) (1-Xi)^ni

pi! ni!

Reputation: Reputation: opinion of one entity about another

Trust: Trust: Expectation of one entity about another.

Reputation space to Trust Reputation space to Trust spacespace

Let Ti (<pi ,ni >)=(pti ,nti ,uti ) be the transformation from binary event <pi ,ni > to trust rating (pti ,nti,uti )

while True For all the nodes s and t in the agent node radio range For event e1 to en Agnet node gets the binary event <pi ,ni > Agent computes the trust rating Tsti; If (Tsti) < a certain value Break; End if End for The agent broadcasts the trust rating Tsti; End for If the time is the begin of window time The agent broadcasts all the trust rating Tsti; End If End While

Modules used:◦ Wireless sensor networks (xA, xB…xN)

◦ Agent nodes (xi)

◦ Intruder nodes (xm)◦ Traffic data ()◦ Events generator

Need to design a special Agent node Higher processing power for the agent node Complex architecture Protection of agent node

Protect agent node from discovery. Broadcast trust rating to the remote

monitoring facility.

This trust model can be used in large scale wireless networks

It provides a more accurate guarantee along with cryptographic mechanisms in detecting malicious nodes of different events in sensor networks

Questions?Questions?