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Ayan Banerjee & Karthik Thangavel
Project GoalsStudy of present state of security in Body Area
Networks(BAN)
Cyber-Physical securityResource FootprintEnergy efficiencySustainability
Effect of security on present day BANs
Vision of security in future wearable sensor platformsIntel Atom based wearable platforms
Body Area Networks (BAN)
A network of low capability sensors (physiological, environmental and activity monitoring)
Sensors communicate with each other through wireless media
Base Station is a gateway for the sensors to the internet
SpO2
EKG
EEG
BP
Base Station
Motion Sensor
Base Station
Sensors
Environmental sensorsPhysiological sensorsActivity sensors
Why ?BANs deal with sensitive information
Wireless media open to security breaches
Requirements Integrity
Confidentiality
Authentication
Plug-n-Play
Security in BAN
Non intrusive and low deployment overhead Traditional Schemes not applicable Can a cyber–physical approach provide the solution?
Cyber-Physical Security
Interaction through sensing
Feedback
Use this to provide security
Signal Processing
Cryptographic primitives
Cyber-Physical Security
The term Cyber-physical implies interaction of computing world with the physical environment
PKA
Index
Peak V
alu
es
PV
FF
T V
alu
es
Peak V
alu
es
Index
PV
FF
T V
alu
es
SENSOR 1
SENSOR 2
Time Time
FFTFFT FFTFFT
Peak DetectionPeak Detection
Index
Peak DetectionPeak Detection
Index
QuantizeQuantize QuantizeQuantize
Polynomial Generation and evaluation
Polynomial Generation and evaluation
Fs = [fs1 fs
2 …….. fsn]
Fr = [fr1 fr
2 …….. fr
n]
fs1
p(fs1)
fsn
p(fsn)
p(fs2)
fs2
cfi,di
Adding ChaffAdding Chaff
Transmit VaultTransmit Vault R Receive VaultReceive Vault
p(x)Lagrangian Interpolation
Lagrangian Interpolation
TransmitAcknowledgement
TransmitAcknowledgement
ReceiveAcknowledgement
ReceiveAcknowledgement
Sensing Sensing
Extensive experiments with Plethysmogram data Data obtained from 10 volunteers
Data collected using Smith Medical pulse oximeter boards
Processing done in MATLAB environment
Related Work PKI based security [1]
The idea of using signals from environment to provide security was first proposed in [2] and [3]
[3] proposed an algorithm to generate security keys from localized measurements of Inter Pulse Interval signals.
[4] proposes a secure key agreement protocol PKA (Physiological value based Key Agreement)
Resource Usage ? Energy Efficiency ? Sustainability ?
1. D. J. Malan, M. Welsh, and M. D. Smith. A Public-Key Infrastructure for Key Distribution in TinyOS Based on Elliptic Curve Cryptography. pages 71–80, Oct 2004. In Proc. of IEEE 2nd Intl. Conf. on Sensor & Ad Hoc Comm. & Networks.
2. S. Cherukuri, K. Venkatasubramanian, and S. K. S. Gupta. BioSec: A Biometric Based Approach for Securing Communication in Wireless Networks of Biosensors Implanted in the Human Body. pages 432–439, Oct 2003. In Proc. of Wireless Security & Privacy Workshop 2003.
3. K. Venkatasubramanian and S. K. S. Gupta. Security for Pervasive Health Monitoring Sensor Applications. pages 197–202, Dec 2006. In Proc. of the 4th Intl. Conf. on Intelligent Sensing & Information Processing.
4. C. C. Y. Poon, Y.-T. Zhang, and S.-D. Bao. A Novel Biometrics Method To Secure Wireless Body Area Sensor Networks for Telemedicine And M-Health. IEEE Communications Magazine, 44(4):73–81, 2006.
5. K. K. Venkatasubramanian, A. Banerjee, and S. K. S. Gupta. Plethysmogram-based secure inter-sensor communication in body area networks. Military Communications Conference, 2008. MILCOM 2008. IEEE, pages 1-7, Nov. 2008.
Resource Footprint
Security
protocol
RAM
requirements
RAM Limit in
motes
Code Size ROM Limit Time (sec)
PVS ~ 7KB 10KB ~ 16 KB 16 KB ~ 20
PKI ~ 4KB 10KB ~ 10 KB 16 KB ~ 34
70% of RAM utilizationNear 100% ROM usage20 seconds to perform a single iteration
TelosB sensors 8 MHz clock10 KB RAMTinyOS operating system that supports NesC
Experimental Setup for power measurementBread board circuit for power measurement
Energy Efficiency & sustainability59 mW of power required for 20 seconds to
perform one iterationOffhand analysis of scavenging techniques
Body Heat – 200 mWRespiration – 420 mWAmbulation – 1500 mWSolar Power – 100 mW/cm2
PKA can be sustained using scavenged energy
Effect of security in present day BANPros
SecureEnergy efficientSustainable
ConsHigh memory usageApplications getting complexSecurity will be obtrusiveRequire more and more computing in sensor
nodes
Vision of a future BAN
Intel Atom based sensors as nodes ?High computing capability
1.6 GHz processor 512 KB L1 cache
PresentFuture
Open research questionsCan we guarantee energy efficient operation
of Atom based platforms?Can we sustain Atom operation through
scavenging of energy?What effect does the power dissipation in
Atom has on human body?Do we need changes in the security protocols
in order to sustain operation of Atom based platforms?
Off hand analysisAtom requires 2W of power at normal
operation and 0.5 W in deep sleep states.Source Power
Gain (mW)
Hrs of
scavenging
operation
in a day
Energy
stored
(J)
Energy
leaked
(J)
Available
energy
(J)
Hrs of
operating
ATOM in
deep
sleep
Hrs of
operating
Atom in
normal
mode
Fsleep
Body Heat 200 – 320 24 4.8 –
7.68
0.57 –
0.92
4.74 –
7.58
9.48 –
15.16
2.37 –
3.790.9
Respiration 420 4 1.68 0.02 1.64 3.28 0.82
Ambulation 1500 –
1600
6 9 - 9.6 0.11 –
0.12
8.89 –
9.48
17.78 –
18.96
4.45 –
4.74
Sun Light 100 – 200
(on a 1cm2
– 2cm2
photovoltai
c cell)
3 0.3 –
0.6
~0.01 0.3 – 0.6 0.6 – 1.2 0.15 –
0.3
ConclusionsSecurity has huge resource overhead on
present day wireless sensor platforms
Sensor node capability have to be increased in order to provide security along with complex applications
Atom based platforms are promising