21.08.2013 Views

Protocols for Secure Communication in Wireless Sensor Networks

Protocols for Secure Communication in Wireless Sensor Networks

Protocols for Secure Communication in Wireless Sensor Networks

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

46 Chapter 2. <strong>Wireless</strong> <strong>Sensor</strong> <strong>Networks</strong> and Their Security<br />

falsified data (false positives <strong>in</strong> the sense of an <strong>in</strong>trusion detection system).<br />

Exist<strong>in</strong>g approaches <strong>for</strong> secur<strong>in</strong>g the process of data aggregation [146, 186]<br />

aim at m<strong>in</strong>imiz<strong>in</strong>g the error that may be <strong>in</strong>troduced by a fraction of malicious<br />

nodes. Additionally, the data reported by aggregat<strong>in</strong>g nodes may be rejected if<br />

it is discovered that the underly<strong>in</strong>g raw data is <strong>in</strong>consistent with the aggregaded<br />

value. This verification can be per<strong>for</strong>med by sampl<strong>in</strong>g a small portion of the<br />

raw data.<br />

2.7.5 Location Verification<br />

In most sensor network applications, it is of importance not only what phenomenon,<br />

but also where it has been detected. When the location is reported<br />

<strong>in</strong>correctly, responsive actions may be misguided. This not only wastes resources<br />

but also leaves the location where the phenomenon actually occurred<br />

unattended. A malicious report with a falsified location can thus <strong>in</strong>flict heavy<br />

damage.<br />

A solution to this problem is the verification of the location of the report<strong>in</strong>g<br />

node. If the report<strong>in</strong>g node has to conv<strong>in</strong>ce other nodes that it is <strong>in</strong>deed located<br />

at the reported location, it is much less likely that a falsely reported location is<br />

be<strong>in</strong>g accepted.<br />

A technique <strong>for</strong> location verification is proposed <strong>in</strong> [158]. It assumes that<br />

the location verifier and location prover can communicate via a radio <strong>in</strong>terface.<br />

Additionally, the prover has to generate an ultrasound signal which the verifier<br />

receives. First, the prover announces to the verifier through the radio <strong>in</strong>terface<br />

its distance from the verifier. The verifier then sends a nonce to the prover (also<br />

through radio) which is immediately reflected by the prover on the ultrasound<br />

channel. If the roundtrip time of the nonce is with<strong>in</strong> appropriate limits, the<br />

verifier can safely assume that the prover is with<strong>in</strong> the the announced range.<br />

Through triangulation us<strong>in</strong>g multiple cooperat<strong>in</strong>g verifiers, the exact position<br />

of the prover can be determ<strong>in</strong>ed.<br />

A different approach <strong>for</strong> distance bound<strong>in</strong>g, which is based on a s<strong>in</strong>gle<br />

communication channel that could be radio-frequency or optical, is described<br />

<strong>in</strong> [77]. It demonstrates that distance bound<strong>in</strong>g is achievable at quite low cost.<br />

Its usage <strong>in</strong> wireless senos networks thus seems feasible. However, the approach<br />

as described relies on an asymmetric architecture as it is <strong>in</strong>tended <strong>for</strong><br />

RFID tags or contactless smart cards. The verify<strong>in</strong>g node (RFID reader) carries<br />

a much larger burden than the node (RFID tag) prov<strong>in</strong>g its location. In addition,<br />

several constra<strong>in</strong>ts, such as ultra-wideband, are imposed on the radio channel.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!