Subject: RE: Mobile Location Based Service user privacy (commercial issue)

From: [email-masked]
Date: Mon, 23 Jul 2001 15:53:21 +0300

Hi Randy & David,

> i missed the part where the daughter makes the decision of what and if
> to reveal.

Exactly.  Further more, if once the father the daughter's location, what
prevents him from sharing it with someone else?

Replace daughter/father with employee/employer or customer/service
provider or even citizen/government & you will quickly realize that
this is one messy problem.

I think PULL model will not & should not work here.  

br,
John

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From: Christian Hauser <[email-masked]>
Date: Mon, 23 Jul 2001 15:34:52 +0200 (MEST)

Hello,

> prevents him from sharing it with someone else?
I think, there will never be any possibility to prevent this. Once, somebody
does know an information, he will be able to share it with everybody (at
least by other communication paths like personal speech).

> I think PULL model will not & should not work here.

In my opinion, a PUSH model will not be sufficient since every time,
somebody wants to know your location, you must push your location to him (and click
on your device; at least if you do not have stored a profile for the
requestor). 

So I think, we should also consider a PULL model for being universal and
considering all possibilities. Therefore, we should search for meanss to protect
access to location information for that purpose.

Best regards,

Christian Hauser

Institute of Communication Networks and Computer Engineering
University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany

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From: Christian Hauser <[email-masked]>
Date: Tue, 24 Jul 2001 10:20:27 +0200 (MEST)

Hello,

> My personal preference is a pull model with explicit
> support for proxies.  The proxy pulls the actual location;
> other clients pull from the proxy.  The proxy needs to
> be trusted.  I like this model because it has a small load
> on the actual device; which often has constrained compute
> power and bandwidth.  The proxy can support push or pull.
> I believe the work of this group should support both.

I agree. In my opinion, we should try to minimize necessary trust in a
possible proxy, e.g. by enabling pseudonymous usage. Of course, it must be trusted
with respect to correct functionality (especially of security and privacy
functions).

Best regards,
Christian Hauser

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From: [email-masked]
Date: Sun, 29 Jul 2001 23:02:33 +0300

Hi Christian,

> I think, there will never be any possibility to prevent this. 
> Once, somebody does know an information, he will be able to share 
> it with everybody (at least by other communication paths like 
> personal speech).

Exactly - we ran up against this problem with the SPATIAL BOF.  One
option is NEVER to transport your location to anyone. I'm not 
advocating this - but someone will raise this.

John

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From: Christian Hauser <[email-masked]>
Date: Mon, 30 Jul 2001 09:47:26 +0200 (MEST)

Hi John,

> advocating this - but someone will raise this.

The only possibility I see, is to use different pseudonyms with different
parties one is in contact with. These pseudonyms must neither be linkable to
each other (i.e. nobody can see, that two different pseudonyms refer to the
same person) nor to the user's real identity. 

Thus, only those parties knowing the same pseudonym can exchange and
aggregate the user's location information. Other parties, that know the user (and
his location information) under a different pseudonym cannot collaborate and
aggregate more location information than the user is willing to disclose.

Again, there will remain the possibility that some pseudonyms are revealed
(accidently or with purpose by other communication paths), thus allowing to
link them (and the respective location information) to a single user.

Actually, this approach cannot totally prevent the problem of sharing
information with other parties (as this will not be possible), but I think it will
provide the user with a means to control it to a certain degree.

Best regards,

Christian Hauser