SeRLoc: Secure Range-Independent Localization for Wireless Sensor Networks Presenter: Yawen Wei Author: Loukas Lazos and Radha Poovendran Network Security Lab, Dept. of EE, University of Washington, Seattle, WA

Problem: Enabling nodes of a wireless sensor network to determine their location even in the presence of malicious adversaries. Design Goal: Decentralized implementation Resource efficiency Robustness against security threats

Outline Overview SeRloc Algorithm Comparison & Simulation Conclusion

Overview What is Localization System? How to determine position? (Schemes) 1.range-dependent GPS, Active Badge, Active Bat, Cricket 2.range-independent DV-hop, amorphous localization, APIT, Centroid Why security?

Range-dependent Location System Time of arrival (TOA) Angle of arrival Signal strength RF, acoustic, infrared and ultrasound Disadvantages (x1,y1); (x2,y2);(x3,y3)

SeRloc Algorithm Network Model Location Determination Security Scheme Threat Analysis

Network Model N: unknown locations L: known locations and orientations, “locators” spatial homogeneous Poisson point process

SeRloc: Location Determination Secure Range-Independent Localization a. the locator’s coordinates b. the angles of the antenna boundary lines c. R: the locator-sensor-communication range d. Overlapping region e. CoG (Center of Gravity)

Step 1: Locators heard Step 2: Search area

Determination of the search area A rectangular area of size less than A rectangular area of size greater than

Step 3: Overlapping region-Majority vote Step 4: Location estimation

SeRloc: Security Scheme Encryption: Global symmetric key Sensor s & locator shares pairwise key Locator ID authentication Collision-resistant hash function (e.g. MD5) Beacon of locator Li

SeRloc: Threat Analysis Types: Wormhole / Sybil / Compromised nodes Wormhole attack Packet leshes: geographical / temporal Time measuring in challenge-reply scheme

Wormholes 1. Sector uniqueness property : area of locators heard by origin point : area of locators heard by s

Wormholes 2. Communication range violation property A sensor cannot hear two locators that are more than 2R apart

the first message: q = k − 1 the last message: q = 0 All locators wait for a q ∗ Ts time

SeRloc: Threat Analysis Sybil Attack and Compromised nodes Multiple network entities Assume sensor identities Assume locators (Not directly heard)

Outline Overview SeRloc Algorithm Comparison & Simulation Conclusion

Comparison Dv-hop and Amorphous localization

Comparison APIT localization 5

Simulation Localization Error vs. Locators heard Localization Error vs. Antenna Sectors Localization Error vs. Sector Error Localization Error vs. GPS Error Communication Cost vs. Locators Heard

Conclusion Secure localization in WSN Range independent Decentralized Security mechanisms Threats Higher accuracy and fewer locators