Source-Location Privacy Protection in Wireless Sensor Network

1
Source-Location Privacy Protection in Wireless
Sensor Network

• Presented by
• Yufei Xu
• Xin Wu
• Da Teng

2
Outline

• Introduction
• Related Work
• Model and Assumptions
• Implementation
• Theoretical Analysis
• Conclusion

3
Introduction

• Wireless Sensor Network
• 1. A
  set of low-cost radio devices
• 2. Supplied with limited amount of
  
• energy
• 3. Through multi-hops to deliver
• data to the base station

4
Introduction (Cont.)

• Source-location Privacy Problem in Wireless
  Sensor Network
• Open architecture of the underlying
  wireless-communication technology
• An adversary can easily detect the source by back
  tracing the routing path
• Evaluating Source-Location Privacy Protection
  Techniques
• Safety Time
• The number of messages sent by source before
  it is identified
• Energy Consumption Level
• Total number of messages sent within the
  entire sensor network

5
Related Work

• Basically, techniques for preserving
  source-location privacy are built upon routing
  protocols
• Two popular routing protocols employed in sensor
  network
• Flooding Routing
• The source forwards a message to all its
  neighbours
• Subsequent sensor nodes also forward the message
  to their neighbours
• Each sensor node only forward the same message
  once
• Single-Path Routing
• Only one path is established between the
  source and the base
• station
• e.g. the shortest path

6
Related Work (Cont.)

• Both of them cant protect the source-location
  privacy in sensor network
• As an approach, fake source messaging is proposed
  in 1
• Introduce fake source which generates false
  messages to mislead the adversary
• Fake messages have same length and also encrypted
  so that an adversary cant differentiate with the
  actual messages.
• As indicated in 2, this approach has a set of
  limitations
• Not efficient in energy conservation
• Location of fake source is important
• Frequency of message generation is also important

7
Related Work (Cont.)

• As a contribution, the phantom routing approach
  is proposed in 2
• Phantom routing contains two phases
• Directed random walk phase to deliver a message
  to a phantom source (either sector-based or
  hop-based random walk)
• Deliver the message from phantom source to base
  station by using either flooding or single-path
  routing
• As indicated in 3, phantom routing still has
  limitations
• It may lead the pre-termination of the random
  walk phase due to the inappropriate selection of
  random walk direction
• Thus there may be performance dropdown in certain
  area of the sensing field

8
Related Work (Cont.)

• As an improvement, a self-adjusting directed
  random walk approach is presented in 3
• It divides the neighbour set into four directions
  (E, W, N, S)
• The real source randomly selects one direction as
  the random walk direction
• By encoding the direction vector into messages,
  it allows self-adjusting of random walk even when
  random walk is blocked on one direction
• When two directions are blocked, a predetermined
  ratio is used to determine whether to continue
  the random walk or not
• However, we find that the above approach can be
  further improved

9
Model and assumptions

• A simulative environment is created for
  estimating performance.3
• a square area of 6000x6000(m2).
• 10000 sensor nodes are located randomly in it.
• the transmission range of each sensor node is
  chosen in a way such that a sensor, in average,
  has 8.5 neighbors.

10
Model and assumptions (Cont.)

• the sink is set at the center of this area.
• there is only one monitored asset.
• its location remains unchanged before it is
  caught by the adversary.
• 4 landmarks are set at 4 corners of this square,
  which will generate a message flood to help every
  sensor get location information of itself.

11
Model and assumptions (Cont.)

• On the other hand, an adversary may adopt two
  kinds of tracing strategy.
• Patient Adversary is referred as the adversary
  waits at a location until he receives a new
  message.
• Cautious Adversary which means he waits at a
  location for a specific period of time if no
  message arrives within this period, he will
  return to its previous location.

12
Implementation

• Direction and position
• four distinct directions NE,NW,SW,SE -- more
  precise.
• square area is divided into four parts.
• each node belongs to one part.
• another useful info is the distance to sink
  hops number.
• neighbors are grouped into four sets.

13
Implementation (Cont.)

• Goal for random walk
• for the phantom routing protocol, the randomness
  of choosing phantom source is very important
  unpredictable path.
• it can be noticed that the farther from the
  phantom source to the real source, the better the
  location-privacy can be protected.

14
Implementation (Cont.)

• Workflow of improved method
• each node maintains 4 lists for its neighbors.
• before random walk, the real source checks
  whether it is near the center by comparing a
  threshold Dsink and its hops from sink.
• if in circle -gt any direction
• if not -gt direction to opposite part
• send msg to a neighbor in that direction

15
Implementation (Cont.)

• when a node receives msg, it checks its hops
• if hops gt hwalk -gt take shortest-path to sink
• if not -gt deliver to a neighbor on the way
• if a node find no neighbor on the way, it change
  direction and forward msg.
• if a node is in a corner, it just stops
  forwarding and begin to send msg to sink using
  shortest-path routing.-- no need to continue
  random walk coz msg has already traveled long
  enough.

16
Theoretical Analysis

• Longer effective distance
• Phantom Routing 180 degree
• Our improved approach 90 degree

17
Theoretical Analysis (Cont.)

• smaller probabilities to hit the boundary

• Phantom Routing
• oscillation-way ? near
• Our improved approach
• relative position?
• far lowest likelihood

18
Theoretical Analysis (Cont.)

• Less energy consumption
• Phantom Routing directional information
• Our improved approach no directional information

19
Conclusion

• Our approved approach achieves a longer safety
  time without consuming more energy than its
  original version. It is better than
  self-adjusting phantom routing in protecting
  source-location privacy.

20
Reference

• 1 Ozturk, C., Zhang, Y. and Trappe, W.,
  Source-location privacy in energy-constrained
  sensor network routing, Proceedings of the 2nd
  ACM workshop on Security of ad hoc and sensor
  networks SASN '04, pp. 88-93, Oct. 2004
• 2 Kamat, P., Zhang, Y., Trappe, W. and Ozturk,
  C., Enhancing Source-Location Privacy in Sensor
  Network Routing, Proceedings of the 25th IEEE
  International Conference on Distributed Computing
  Systems, pp. 599-608, June 2005
• 3 Zhang, L.,A self-adjusting directed random
  walk approach for enhancing source-location
  privacy in sensor network routing, Proceedings
  of the 2006 international conference on Wireless
  communications and mobile computing, pp. 33-38,
  2006.

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Question

• Any Questions ?