cell phone anonymity

[Adam Shostack]

On Mon, Jan 08, 2001 at 12:59:26AM -0500, Ray Dillinger wrote:
| 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 
| 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.  (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).  So if you're into hard 

There are a couple of location technologies in use.  GPS is not (as
far as I know) actually deployed.  Much more common is triangulation,
generally without the handset's cooperation.  New phones will have
tools in them to help with the triangulation process.  All of these
will work if the phone is switched on.  GSM phones talk to the network 
regularly for call-routing optimization purposes.

The E911 requirements in the US include a requirement for covert 
"authorized" querying of the phone's location.  Doubtless, this
message will be strongly authenticated by a police-only PKI, and your
phone will log it for later audit purposes.

You might want to look at 3GPP TS 22.071 or 23.171, which can be found
off of http://www.3gpp.org/3G_Specs/3G_Specs.htm

Also, I'll point out that it should be possible to combine the RF
fingerprinting techniques being used to combat cloning with
triangulation techniques, and track phones regardless of what crypto
they're using.  You are, after all, carrying around a broadcasting
radio.

Adam

-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume