A Test-bed for Secure Hierarchical Data Aggregation in
Wireless Sensor Networks
Students: Vimal Kumar,
Joshua McCarville-Schueths
(Computer Science Department )
Faculty Advisor: Dr. Sanjay Madria, Computer Science Department
INTRODUCTION
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IMPLEMENTATION
Wireless sensors are small battery powered devices with
wide applications in areas such as battlefield surveillance,
wildlife monitoring, healthcare, etc.
Since the biggest reason of power consumption on sensors
is wireless communication, we focus on minimizing it.
The Platform used was nesC on Tinyos 1.1.15
MICA2
TELOSB
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Code was implemented on Mica2 and TelosB motes.
MPR400CB
TI MSP430
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8 bit Microcontroller
16 bit Microcontroller
Used TinyECC library for Elliptic curves with160 bit curve
secp160r1. This provides160-bit encryption keys.
Program flash
128kB
48kB
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RAM
4kB
10kB
Clock Speed
7.3827 MHz
8 MHz
Data is encrypted by Elliptic curve ELGamal (ECEG) and
signed by our modified version of Elliptic curve digital
signature algorithm (ECDSA).
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ECEG is a homomorphic encryption scheme and the
modified ECDSA is an aggregate digital signature scheme.
Processor
The challenge on wireless sensors is to devise algorithms
which require least energy so as to make the sensors last
longer.
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Security operations are power intensive. In a secure
protocol, such operations should be kept to a minimum
while maintaining optimum security.
Traditional Encryption
Enc[Message1] + Enc[Message2] ≠Enc[Message1 + Message2]
DATA AGGREGATION
Base
Station
Base
Station
Intermediate nodes aggregate data
Homomorphic Encryption
Enc[Message1] + Enc[Message2] = Enc[Message1 + Message2]
I see 6 soldiers
Digital Signatures
Sign[Message1] + Sign[Message2] ≠ Sign[Message1 + Message2]
Additive Digital Signatures
Sign[Message1] + Sign[Message2] = Sign[Message1 + Message2]
MICA2
Operation
Encryption
Sign
Addition of ciphertext
Addition of signatures
Keeping soldier count using data aggregation
Time Taken (ms)
4406.207
2477.036
335.2
0.09
Addition of Public keys 157.67
Data aggregation helps conserving energy by reducing the
number of messages sent with in the network.
OBJECTIVES
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Develop a secure end to end data aggregation scheme with
lesser power consumption.
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Propose security operations(encryption, digital signatures)
to support the end to end communication.
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Write an efficient implementation of these security
operations.
Write a reconfigurable implementation which can be easily
customized to fit various platforms and motes.
Energy Consumed (mJ)
105.75
59.44
8.04
0.002
3.78
Time Taken (ms)
10573.63
5890
406.59
0.2
200
Energy Consumed (mJ)
57.09
31.80
2.19
.001
1.08
RESULTS
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The results obtained by the implementation of the code on Mica2
motes are summarized in the table above.
The scheme replaces the decrypt, verify, encrypt and sign
operations on the intermediate nodes, with the three operations ,
namely the addition of ciphertext, signatures and the public keys.
Energy Saving at Aggregators
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MICA2
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TELOSB - 100.39 mJ
SUM-Enc(101)
SUM-Sign(101)
SUM-PK(21,17)
TELOSB
- 97.74 mJ
The code for TELOSB is in the process of optimization. Its
execution times and energy consumption can be further reduced.
Children transmit
the encrypted data
, signature, and the
public key to the
parent
Enc( 58)
Sign(58)
PK(21,19)
Enc( 24)
Sign(24)
PK(13,11)
Enc( 19)
Sign(19)
PK(11,10)
FUTURE WORK
 Extend the network lifetime by further optimizing the code.
 Minimize the redundancy of the messages in the network by
implementing data compression at the source nodes.
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Implementation of the algorithm on GumStix
ACKNOWLEDGEMENTS
This research is partly supported by Intelligent Systems Center.
REFERENCES
Vimal Kumar, Joshua McCarville-Schueths and Sanjay
Madria, “A Test-bed for Secure Hierarchical Aggregation in
Wireless Sensor Networks, Demo paper in MASS 2010