# Key Distribution and Route Selection in Wireless Sensor Networks

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21 Νοε 2013 (πριν από 4 χρόνια και 7 μήνες)

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Key Distribution and Route Selection
in Wireless Sensor Networks

Nathan Lewis, Noria Foukia

{
ndlewis,nfoukia
}@
infoscience.otago.ac.nz

Information Science Institute

University of Otago

Dunedin, New Zealand

Objectives

Efficiency of distribution of pair
-
wise
encryption keys

Reliability of route selection

Overview

Key Distribution

Trust

Neighbor
-
based key distribution

Route Selection

Trust and Cost

Expenditure

Avoiding Loops

Testing routes

Key Distribution

By Base Station

All keys created by the Base Station

Nodes must communicate with the Base Station
-
wise keys

Nodes may be many hops from the Base Station

Key Distribution

By Neighbor

Common trusted neighbor can create a key

Initial trust calculation

Communications savings

Number of transmissions/node required for all nodes to
acquire pair
-
wise keys with their immediate neighbors.

40
50
60
70
80
90
100
100
200
300
400
500
Key Distribution by Neighbors - Degree = 10
Key Distribution by BS - Degree = 10
Key Distribution by Neighbors - Degree = 15
Key Distribution by BS - Degree = 15
Route Selection

Trust and Cost

Route Trust
(TR) is the minimum of the trust
values that each node has for the next hop on the
route

Route Cost
(CR) is the sum of the costs of each
hop to the destination

TR
A→B →BS

= min(TN
A →B
, TR
B →BS
)

CR
A →B →BS

= CN
A →B

+ CR
B →BS

Route Selection

Expenditure

How much we expect to pay to use a given route

E
A

= CR
A

+ (1

TR
A
)CR
B

CR
A

is the cost to use route A

(1

TR
A
) is the probability of route A failing

CR
B

is the cost to use route B

E
B

= CR
B

+ (1

TR
B
)CR
A

Compare two routes

Calculate E
A

and E
B

and select route with smaller
Expenditure

Multiple routes (C, D, ...)

Avoiding Loops

Loss of route information messages

Inconsistent picture of the state of the neighborhood

Possibility of selecting route that causes a loop

First send route test message

If message is received at destination then route does
not contain loop

If message returns to sender then sender knows a
loop exists and can avoid using that route

Summary

Neighbor
-
based pair
-
wise key distribution
reduces communications with large numbers
of nodes

Route selection requires only local
information, has simple calculation and only
requires a single pass through the list of
available routes

Reliable method of avoiding loops

Future work

May not need to test whole route, limit
number of hops