Using Auxiliary Sensors for Pair-Wise Key Establishment in WSN Source: Lecture Notes in Computer Science (2010) Authors: Qi Dong and Donggang Liu Presenter:

Using Auxiliary Sensors for Pair-Wise Key Establishment in WSN

Source: Lecture Notes in Computer Science (2010)Authors: Qi Dong and Donggang LiuPresenter: Hsing-Lei WangDate: 2010/09/03

Outline

Introduction Pair-Wise Key Establishment Analysis and Discussion Comparison Security Reinforcing Version Conclusions

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Introduction The proposed scheme’s main idea:

Deploy assisting sensor nodes to help key establishment between two regular sensor nodes

Advantages: Very high probability of establishing a shared

key Majority of sensors only need to store a single

key High resilience to node compromise Implementation on TelosB Motes

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Protocol Description(1/3)

Initialization Let = network size, = assisting sensor

nodes Base station generates Master Key for

node Assisting node will get preloaded with

For instance, 1MB flash memory can store the hash images for 128,000 nodes (1 hash image=8bytes)

n m

uK

i

u

uH K i

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Protocol Description(2/3)

Pair-Wise Key Establishment

u v

2

1 1,

uH Ku v

2,

uH Ku v

2 2uH KR

1 1uH KR

1 1vH KR

2 2vH KR

, 1 2 ...u v lK R R R

Assisting node i = 1,2,…,m

Assisting node i = 1,2,…,m 5

Protocol Description(3/3)

Supplemental Key Establishment

u

t2

1

v

2,

uH Ku v

2 2uH KR 2 2vH KR

1 2 2{ , ,..., }ul H KR R R

, 1 2 ...u v lK R R R 6

2,

uH Ku v

Analysis and Discussion (1/3)

Probability of Establishing Keys:

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Analysis and Discussion (2/3)

Resilience against Node Capture

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Analysis and Discussion (3/3)

Overheads Storage:

regular sensor: a single master key assisting sensor: n hash values

Computation: a few symmetric key operations and hash

operations Communication:

only one-hop range communication are needed in most case

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Comparison (1/2)

Security Performance Setting:Network size n=20,000 nodes

Neighbors d=50 nodes Each sensor store=200 keys

P=Probability ofdirect key betweentwo sensor

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Comparison (2/2)

Security Performance Setting:Network size n=20,000 nodes

Neighbors d=50 nodes Each sensor store=200 keys

P=Probability ofdirect key betweentwo sensor

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Security Reinforcing Version

Security issue: Once an assisting node is compromised, the

attacker will get all the hash values and discover all the random keys generated by the node

Method to fix: Set a sequence number =0 and

in initialization After setup a pair-wise key between u and

v,

uS u uH H K i

replace with and increase and by 1u u u vH H H S S

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Conclusion

This paper developed a novel scheme to establish the pair-wise keys in WSN Using of assisting sensor

The analysis indicates the scheme has several significant advantages over existing scheme High probability to establishing shared keys Good resilience against node capture Lower overhead (storage, computation, etc.)

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