Location Privacy Protocols, was Re: GPS trail - crazy idea

Nick Johnson arachnid at notdot.net
Fri Jul 6 00:31:24 CEST 2007

On 7/6/07, Paul Wouters <paul at xelerance.com> wrote:
> A paper was presented at the Privacy Enhancing Technologies
> conference in Ottawa a few weeks ago:
> Louis, Lester and Pierre: Three Protocols for Location Privacy
> Ge Zhong, Ian Goldberg, Urs Hengartner (University of Waterloo)
> See: http://petworkshop.org/2007/papers/PET2007_preproc_Louis_Lester.pdf
> Especially, an implementation of the Pierre protocol would be
> interesting. In essence, using the protocol, two people can
> reveal each others location but only when they are close to
> each other. In other words, if you are not close to each other,
> the other person does not obtain your location information.
> Additionally, you can lie about your location if you just do not
> want to be found right now, without revealing to the other person
> that you are lying.
> This would be a very cool IM plugin for Openmoko, and a good use
> of the GPS in Openmoko without losing your privacy.

This does indeed look interesting. The issues I see are:
- All the protocols rely on communication between peers, which is
difficult in cell networks. Naturally this could be worked around by
introducing a third-party as a relay, though.
- Determining which friends are near you would require conducting the
protocol with every one of them on a regular basis. This would be
rather cumbersome for a large-scale system.

-Nick Johnson

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