A%20Security%20Protocol%20for%20Sensor%20Networks

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A Security Protocol for Sensor Networks

• Khadija Stewart, Themistoklis Haniotakis and
  Spyros Tragoudas
• Dept. of Electrical and Computer Engineering
• Southern Illinois University

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Outline

• Abstract
• Previous work
• Proposed method
• Uncorrelating the bits
• Encryption scheme
• Reverse uncorrelation and decryption scheme
• 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

• 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

• Keyless methods target flexibility
• Rabin 1989
• Papadimitratos et al 2003

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Proposed Method Outline

• 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)
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Proposed Method Uncorrelating the bits

• 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

011 001 100 010 101 110 111
Example of an LFSR with k 3 and T 7
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Proposed Method Encryption Scheme

• For i0 to m-1
• Xi bi,0 XOR bi,1 XORXOR bi,2n-1
• For i0 to m-1
• For j0 to 2n-1
• Ci,j Xi XOR bi,j

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Proposed Method

• 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

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Proposed Method De-uncorrelation and
decryption Scheme

• Procedure decode
• For i0 to m-1
• Xi ci,0 XOR ci,1 XORXOR ci,2n-1
• For i0 to m-1
• For j0 to 2n-1
• bi,j Xi XOR ci,j
• Sub-messages reverse uncorrelated in a similarly
  designed LFSR

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Hardware Overhead

• The hardware requirements are
• An m bit LFSR
• Two levels of XOR gates
• 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
• 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
• No single intruder node was able to intercept
  a complete message

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Experimental Results Multiple intruders

• 70 motes

intruders of disjoint paths of disjoint paths of disjoint paths of disjoint paths
intruders 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 intruders intruders intruders intruders
motes paths 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
• Low resource requirements of proposed method
• Efficiency of proposed method in protecting
  secrecy of messages

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Questions?

• Thank you