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