Position escrow

[Phil Karn]

This is a really difficult issue. Even the most diehard cypherpunk
cannot doubt the usefulness of a cellular position reporting
capability in an emergency situation, when the user *wants* the cops
or whoever to know where he is.  The big problem is how to keep it
from being used (or abused) for "law enforcement" purposes without the
consent of the user.

The main reason GPS receivers are not being used is simple economics:
as small and cheap as they're getting, they're still too big and
expensive for a cell phone. It's not just the electronics, but the
antenna too. And they don't work too well indoors.  So the
manufacturers are developing ways to locate the phone using complexity
in the base station, where it can be shared. Various time-of-arrival
schemes are being proposed. CDMA has an inherent capability because
it (like GPS) uses spread spectrum, although there are near-far
problems to be solved.

I expect the main countermeasure to cellular position tracking will be
the use of one-way pagers. Keep your cell phone turned off, and if you
get a page when you're someplace you don't want them to know, wait
until you leave before you return the page.

Perhaps if the "just turn it off" approach is widely promoted, the
carriers and vendors will see the threat to their business and press
for some safeguards. Otherwise they just won't give a damn.

Phil