cell phone anonymity

[Tim May]

At 12:59 AM -0500 1/8/01, Ray Dillinger wrote:
>On the larger purchases, the costs drop down to the forty-cents-a-minute
>range.  Totally worth it if you really *need* anonymity on the phone. 
>
>Of course, anonymity is relative; these phones have built-in GPS chips
>for 911 calls, and these are activated from the central office, not by

Which of these phones have built-in GPS? Gonna be a real shock to 
Trimble, Magellan, and Garmin that the GPS units they're still 
selling for $100 and up are competing with cellphones given out free 
with new accounts!


GPS is getting cheaper, and may someday appear in even inexpensive 
cellphones, but that day has not yet come.


>a 911-sensing circuit in the handset.  IOW, it is not impossible for
>someone with the right gear and knowhow to query the phone for its
>exact latitude and longitude at any moment when it's in use.

Why do you believe this to be so?

>(I don't
>know whether it can be queried when it's switched off, nor if so whether
>removing the main batteries will stop it).

A backup battery is likely only usable for the local storage of 
temporary parameters, and probably not even that. I don't recall any 
mention with either my Motorola Star-Tac or my current Nokia about 
backup batteries.

Which means that when the main battery pack is removed, the circuitry 
is "OFF." No power to transmit. (And forget passive sensing, as with 
some radio or t.v. tuning coils of old, as that required being very 
close to the coils to detect resonances. And no longer even 
applicable, what with digital tuners.)


>  So if you're into hard
>anonymity, keep it inside a faraday cage when you're not using it and
>don't use it from inside your own dwelling.
>
>Faraday cages don't have to be fancy; a fruitcake tin will usually do.

Removing the battery is easier. Turning the phone off is _probably_ 
(I am convinced of this, but haven't studied it in detail) enough to 
stop any location detection, at least with the current generations of 
cellphones.

(The very long battery life of a turned-off Nokia vs. a turned-on 
Nokia tells us a lot about what it could possibly be transmitting.)

As for Faraday cages, there are easier options that a fruitcake tin. 
Reception is bad enough in mountainous areas  like mine.

Ray, you seem knowledgeable in some areas. But your pontifications on 
California basements, cellphone GPS, etc., are very "Choatean" in 
nature. Something you might want to look at.


--Tim May
-- 
Timothy C. May         tcmay at got.net        Corralitos, California
Political: Co-founder Cypherpunks/crypto anarchy/Cyphernomicon
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