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A Key Management Scheme for Wireless Sensor Networks Using Deployment Knowledge

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Spec Motes. Wireless Sensor Networks (WSN) Deploy. Sensors ... Mica Motes: 128KB Flash and 4KB RAM. Key Management Problem. Key Management Problem ... – PowerPoint PPT presentation

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Title: A Key Management Scheme for Wireless Sensor Networks Using Deployment Knowledge


1
A Key Management Scheme for Wireless Sensor
Networks Using Deployment Knowledge
  • IEEE INFOCOM 2004
  • Wenliang Du, Jing Deng, Yunghsiang S. Han,
    Shingang Chen, Pramod K. Varshney
  • - Reformatted by dhhan_at_cosmos.kaist.ac.kr -

2
Overview
  • Overview of Wireless Sensor Networks (WSN).
  • Security in wireless sensor networks.
  • Why is it different?
  • This papers contributions on key
    pre-distribution in WSN
  • Deployment-based scheme (INFOCOM04)
  • Summary.

3
Wireless Sensors
Berkeley Motes
4
Mica Motes
  • Mica Mote
  • Processor 4Mhz
  • Memory 128KB Flash and 4KB RAM
  • Radio 916Mhz and 40Kbits/second.
  • Transmission range 100 Feet
  • One year battery life
  • TinyOS operating System small, open source and
    energy efficient.

5
Spec Motes
6
Wireless Sensor Networks (WSN)
Sensors
7
Applications of WSN
  • Battle ground surveillance
  • Enemy movement (tanks, soldiers, etc)
  • Environmental monitoring
  • Habitat monitoring
  • Forrest fire monitoring
  • Hospital tracking systems
  • Tracking patients, doctors, drug administrators.

8
Securing WSN (outline)
  • Motivation why security?
  • Why not use existing security mechanisms?
  • WSN features that affect security.
  • This papers work
  • Improved key management schemes.

9
Why Security?
  • Protecting confidentiality, integrity, and
    availability of the communications and
    computations
  • Sensor networks are vulnerable to security
    attacks due to the broadcast nature of
    transmission
  • Sensor nodes can be physically captured or
    destroyed

10
Why Security is Different?
  • Sensor Node Constraints
  • Battery,
  • CPU power,
  • Memory.
  • Networking Constraints and Features
  • Wireless,
  • Ad hoc,
  • Unattended.

11
Sensor Node Constraints
  • Battery Power Constraints
  • Computational Energy Consumption
  • Crypto algorithms
  • Public key vs. Symmetric key
  • Communications Energy Consumption
  • Exchange of keys, certificates, etc.
  • Per-message additions (padding, signatures,
    authentication tags)

12
Constraints (Cont.)Public Key Encryption
  • Slow
  • 1000 times slower than symmetric encryption
  • Hardware is complicated
  • Energy consumption is high

13
Memory Constraints
  • Program Storage and Working Memory
  • Embedded OS, security functions (Flash)
  • Working memory (RAM)
  • Mica Motes
  • 128KB Flash and 4KB RAM

14
Key Management Problem
15
Key Management Problem
Sensors
16
Key Management Problem
Sensors
Secure Channels
17
Approaches
  • Trusted-Server Schemes
  • Finding trusted servers is difficult.
  • Public-Key Schemes
  • Expensive and infeasible for sensors.
  • Key Pre-distribution Schemes

18
Key Pre-distribution
  • Loading Keys into sensor nodes prior to
    deployment
  • Two nodes find a common key between them after
    deployment
  • Challenges
  • Memory/Energy efficiency
  • Security nodes can be compromised
  • Scalability new nodes might be added later

19
Naïve Solutions
  • Master-Key Approach
  • Memory efficient, but low security.
  • Needs Tamper-Resistant Hardware.
  • Pair-wise Key Approach
  • N-1 keys for each node (e.g. N10,000).
  • Security is perfect.
  • Need a lot of memory and cannot add new nodes.

20
Eschenauer-Gligor Scheme
Key Pool S
Each node randomly selects m keys
A
B
E
D
C
  • When S 10,000, m75
  • Pr (two nodes have a common key) 0.50

21
Establishing Secure Channels
B
A
C
22
Improvement Over Eschenauer-Gligor Scheme
23
Observations and Objectives
A
B
F
Property Pr(A, B) Pr(A, F)
Our objective Pr(A, B) gtgt Pr(A, F)
Using deployment knowledge
24
Modeling Deployment Knowledge
Deployment points for a group of sensors
I
A
J
B
K
F
25
Probability Distribution Function of Each
Deployment Group
26
Probability Distribution Function of All
Deployment Group
27
Key pre-distribution Scheme
  • Step 1 Key pre-distribution phase
  • Step 2 Shared-key discovery phase
  • Step 3 Path-key establishment phase

28
Step 1 Key pre-distribution phase
Key Pools
29
Step 1 Key pre-distribution phase- Key Sharing
Among Key Pools -
Horizontal
a
B
C
A
b
b
a
F
D
a
a
Vertical
Diagonal
a
b
b
G
H
I
b
a
30
Step 1 Key pre-distribution phase- Key Pool
Size -
  • Maximal use of the pool

31
Step 2 Shared-key discovery phase
  • By broadcasting to neighbors
  • Challenge-response technique
  • a, EKi(a)
  • i 1,,m
  • Key ring which has m members

32
Step 3 Path-key establishment phase
  • A ?? B
  • Find secure path by using flooding method.
  • Limit the lifetime of the flooding message to
    three hops to reduce flooding overhead
  • Share random key K by using secure path.

33
Local Connectivity
34
Network Resilience
  • What is the damage when x nodes are compromised?
  • These x nodes contain keys that are used by the
    good nodes.
  • What percentage of communications can be affected?

35
Network Resilience
36
Summary
  • Security in WSN is quite different from
    traditional (Wired) network security.
  • Our schemes substantially improves the
    performance and network resilience.
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