Title: Towards clock skew based services in wireless sensor networks

Authors: Md. Borhan Uddin, Claude Castelluccia

Addresses: Department of Computer Science, State University of New York (SUNY), Stony Brook, NY 11794, USA. ' INRIA, Rhone-Alpes, 655 avenue de l'Europe, Montbonnot, 38334 Saint Ismier Cedex, France

Abstract: Clock skew, an inherent property of clock crystals of physical devices, is defined as the rate of deviation of a device clock from the true time. The frequency of a device|s clock actually depends on its environment, such as the temperature, humidity, vibration, electromagnetic interference, as well as the type of crystal. The main contributions of this paper are twofold. First, we experimentally validate that MICAz and TelosB sensor motes have different and unique clock skews. Furthermore, the clock skew of a node can easily be monitored, even via a multi-hop Wireless Sensor Network (WSN). We argue that this feature can be used for identification of the nodes, detection of wormhole and Sybil attacks. Second, we show that the clock skew of a sensor node varies with the variation of temperature. We explain how this property can be used to detect malicious and malfunctioning nodes and to geolocalise them. We also discuss the pros and cons of utilisation of the above two properties for different services in WSNs.

Keywords: clock skews; covert channels; fingerprinting; temperature; malicious mote identification; malfunctioning mote identification; geolocation; measurement; security; multi-hop WSN; wireless sensor networks; wireless networks; clock crystals; sensor motes; node identification; attack detection; wormhole attacks; Sybil attacks; humidity; vibration; electromagnetic interference.

DOI: 10.1504/IJSNET.2011.037302

International Journal of Sensor Networks, 2011 Vol.9 No.1, pp.24 - 37

Published online: 02 Dec 2010 *

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