Transcript A Security Protocol for Sensor Networks

A Security Protocol for Sensor
Networks
Khadija Stewart, Themistoklis Haniotakis
and Spyros Tragoudas
Dept. of Electrical and Computer
Engineering
Southern Illinois University
Outline
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Abstract
 Previous work
 Proposed method
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Uncorrelating the bits
Encryption scheme
Reverse uncorrelation and decryption scheme
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Hardware overhead
 Experimental results
 Conclusions
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Abstract
Sensor networks are extensively used in
military and rescue operations
Need for secure communications
 Memory, computational and energy
resource constraints
 Security protocol must use minimal
resources
 Available security schemes are either
inefficient or expensive
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Previous Work
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Key based schemes
Frankel et al 1989
 Eshenaur et al 2002
 Chan et al 2003
 Liu et al 2003
 Du et al 2005
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Previous Work
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Keyless methods target flexibility
Rabin 1989
 Papadimitratos et al 2003
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Proposed Method: Outline
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Message split into 2n sub-messages
Sub-messages uncorrelated using an LFSR
Sub-messages encrypted
Encrypted sub-messages are routed through
transmission disjoint routes
At the destination, sub-messages are
decrypted and uncorrelation is reversed
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Proposed Method:
Splitting of the message
a0
a1
a2
a3
a4
a5
a6
a7
a8
a9
a10
a11
Number of columns of array B = Number of node disjoint paths
b0,0(a0)
b0,1(a1)
b0,2(a2)
b0,3(a3)
b1,0(a4)
b1,1(a5)
b1,2(a6)
b1,3(a7)
b2,0(a8)
b2,1(a9)
b2,2(a10)
b2,3(a11)
Globecom 05
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Proposed Method:
Uncorrelating the bits
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LFSRs primarily used in circuit testing to produce
pseudo-random patterns
A different LFSR chosen for each sub-message i
Characteristic polynomial and ti are encoded and
appended to the outgoing sub-message
Example of an LFSR with k = 3 and T = 7
011
001
100
010
101
110
111
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Proposed Method:
Encryption Scheme
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For i=0 to m-1
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Xi = bi,0 XOR bi,1 XOR…XOR bi,2n-1
For i=0 to m-1
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For j=0 to 2n-1
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Ci,j = Xi XOR bi,j
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Proposed Method
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Sub-messages are routed through node
disjoint routes
 Routes only need to be node disjoint due to
the use of directional antennas
 A mote can overhear transmission if and only
if it is within transmission range and in angular
span of sending node
Globecom 05
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Proposed Method:
De-uncorrelation and decryption Scheme
Procedure decode
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For i=0 to m-1
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For i=0 to m-1
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Xi = ci,0 XOR ci,1 XOR…XOR ci,2n-1
For j=0 to 2n-1
 b
i,j = Xi XOR ci,j
Sub-messages reverse uncorrelated in a similarly
designed LFSR
Globecom 05
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Hardware Overhead
The hardware requirements are:
 An m bit LFSR
 Two levels of XOR gates
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One level is used for encryption and the
other is used with the LFSR
Three levels of multiplexers
2x1 multiplexers at the inputs of XOR gates
 4nx2n multiplexers to initiate LFSR
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Experimental Results:
Area and power requirements
Power consumption of RSA chip is in the
order of 500 mW
 Power and area of ECC module is over
300 mW and 24,000 square microns
 Security module designed and
synthesized in VHDL for a 512 bit ckt
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Power consumption 5 micro Watts
 Area less than 25 square microns
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Experimental Results:
Performance measurements using OPNET
Experiments conducted on networks of
60, 70, 80, 90 and 100 motes with 90
degree directional antennas
 Wireless transmission range set to 25
meters
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Experimental Results:
One intruder
Experiments ran 10 times for each
network size. In each run, a random
node chosen as intruder
 Number of paths = maximum even
number of node disjoint paths
 Used destinations at least two hops
away
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No single intruder node was able to
intercept a complete message
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Experimental Results:
Multiple intruders
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70 motes
# intruders
# of disjoint paths
2
4
6 max
2
6
3
0 0
4
8
6
2 1
6
10
8
4 2
8
12
8
6 2
Percentage of messages intercepted for different numbers of paths
As the number of paths increases, the
number of intercepted messages decreases
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Experimental Results:
Performance of scheme in presence of several intruders
# motes
# paths # intruders
2
4
6
8
10
60
4
0
2
4
4
4
70
6
0
1
2
2
4
80
8
0
1
3
3
4
90
10
0
1
2
2
3
100
12
0
1
2
2
3
Percentage of messages intercepted in the presence of
different numbers of collaborating nodes
Low interception rates even for large number
of intruders
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Conclusions
An encryption method and uncorrelation
scheme for secure message
transmission in sensor networks
 Experimental results show
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Low resource requirements of proposed
method
 Efficiency of proposed method in protecting
secrecy of messages
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Questions?
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Thank you
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