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Adaptive key pre-distribution model for distributed sensor networks

Author: C.-S. Laih, M.-K. Sun, C.-C. Chang and Y.-S. Han Source: IET Communications, vol. 3, no. 5, pp.723-732, 2009. (Impact Factor = 0.751)Presenter: Yung-Chih LuDate: 2010/08/20

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Outline

Introduction Proposed Scheme Performance Evaluation Security Analysis Conclusion

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Introduction(1/3)

Distributed Sensor Network

Base station

location finding system

mobilizer

transceiver Unit

sensing unit processing unit

sensordigital/analogconverter

microprocessor

storage device

power unit

Powergeneration

Sensor Architecture

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Introduction(2/3)

key agreement protocol Key pre-distribution:

Keys are distributed to all sensor nodes prior to deployment.

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Introduction(3/3)

Constraints Limited energy consumption Low transmission range Limited Memory overhead

Requirements High network connectivity Robust resilience against node capture Low communication overhead

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Eschenauer-Gligor Scheme(1/3) Key pre-distribution phase

Key poolKeys

Key identifier

Key poolKeys

Key identifier

Key ring(k keys)

H-sensor

Key identifier = key mod 232

Kci = EKx(ci) Kx = K1 ,…, K⊕ ⊕ k

ci = H-Sensor ID

H-Sensor : L-Sensors ID 、 L-Sensors key identifiers and Kci

L-Sensor : k keys 、 key identifiers and Kci

:L-Sensor

L-Sensor : Low-end sensorH-Sensor : High-end sensor

L. Eschenauer and V. Gligor. “A Key-Management Schemefor Distributed Sensor Networks.” In Proc. 9th ACM Conference on Computerand Communication Security, pp.41-47, Nov. 2002.

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Eschenauer-Gligor Scheme(2/3) Shared-key discovery

Key ring(k keys)

H-sensor

:L-Sensor

Step1: Each L-sensor Broadcasts a list of key identities.

Step2: L-sensor runs a challenge-response protocol if L-sensor find the common key.

Eki(α)

Eki(α)

α = Dki[Eki(α)]

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Eschenauer-Gligor Scheme(3/3) Path-key establishment

Key ring(k keys)

H-sensor

:L-Sensor

Ekc(kp)

Ekc(kp)

Ekp(α)

α = Dkp[Ekp(α)]

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Proposed Scheme(1/5)

Shamir’s threshold scheme

PT: prime number PT ≧ a0

t : degree of polynomial a0 : group key

Example:

t=3 ; a0=1234 ; n = 6

g(x) = 94x2+166x+1234

(1,1494);(2,1942);(3,2578);

(4,3402);(5,4414);(6,5614)

g(x)

= 94x2+166x+1234

g(0) = 1234

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Proposed Scheme(2/5)

Key poolKey pool

S1S1

S2S2

SvSv

Sub-key pool

……

……

……

….

|S| :the number of keys in key pool v :the number of sub-key poolsGK: group key|d| = |S| / v

sk = sub-keyID = sub-key identifierskij = gi(IDij) i=1,2,…,v j=1,2,…,|d|

g1(x) GK1

g2(x) GK2

gv(x) GKv

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Proposed Scheme(3/5)

Key pre-distribution phase

Key ring

(τ keys and key ID)

S1S1

S2S2

SvSv

……

……

……

Sub-key pool

sensor

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Proposed Scheme(4/5)

Shared-key discovery phase

H-sensor

:L-Sensor

Step1: Each L-sensor Broadcasts a list of key ID.

Step2: L-sensor runs a challenge-response protocol if L-sensor find the communication key.

q’: the number of common keysEski(α)

Eski(α)

α = Dski[Eski(α)]

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Proposed Scheme(5/5)

Shared-key discovery phaseStep1 ︰ Each L-sensor computes their respective bonus key rings

Step2: Each L-sensor Broadcasts a list of group key ID.

Step3: L-sensor runs a challenge-response protocol if L-sensor find the communication key.

q’: the number of common keys

Key ring

(τ keys and key ID)

bonus key ring

(w group keys And group key ID)

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Performance Evaluation(1/4)

a. number of groups v ＝ 30,size of the key pool |S| = 10000, size of key rings τ = 75

b.value of threshold t = 2, size of the key pool |S| = 1000, size of key rings τ = 40

Connectivity

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Performance Evaluation(2/4)

Local connectivity

Network connectivity

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Performance Evaluation(3/4)

Connectivity

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Performance Evaluation(4/4)

Communication overhead

a. EG scheme

b. Proposed scheme

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Security Analysis

Resilience against node capture

a. τ =40 and p =0.33

b.τ =40 and p =0.5

p: local connectivity

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Conclusion

Dependent keys High connectivity It is able to adjust its system

parameters