[2015] in cryptography@c2.net mail archive
Mobile phones used as trackers
daemon@ATHENA.MIT.EDU (David M Walker)
Tue Dec 30 14:27:50 1997
Date: Tue, 30 Dec 1997 19:08:09 +0000
From: David M Walker <davidw@datamgmt.com>
Reply-To: davidw@datamgmt.com
To: cryptography@c2.net
CC: perry@piermont.com
[Although not strictly cryptography related, the privacy implications
are rather interesting and I thought I would forward this on since
privacy and security issues are related to the list topic. I am NOT
soliciting a large stream of cellphone location postings, though if
I'm in a generous mood I _might_ accept one or two if they are
somehow particularly interesting. -- Perry]
The following article appeared on 29th December 1997 in the Times
(http://www.sunday-times.co.uk). I am the Technical Architect for
the Swisscom Mobile Data Warehouse project and comment below ...
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Mobile phones used as trackers
BY MICHAEL EVANS AND NIGEL HAWKES
MOBILE PHONES can be used as tracking devices to
pinpoint users within a few hundred yards, according to a
report yesterday.
Sonntags Zeitung, published in Zurich, said Swiss police
had been secretly tracking mobile phone users through a
telephone company computer.
"Swisscom [the state-owned telephone company] has
stored data on the movements of more than a million
mobile phone users and can call up the location of all its
mobile subscribers down to a few hundred metres and
going back at least half a year," the paper reports, adding:
"When it has to, it can exactly reconstruct, down to the
minute, who met whom, where and for how long for a
confidential tte--tte."
Swisscom officials confirmed the practice but said
information about mobile phone customers was handed
over only on production of a court order. The newspaper
claimed that about 3,000 base stations in Switzerland
tracked the location of mobile phones as soon as they
were switched on.
Renato Walti, an investigating magistrate in Zurich who
specialises in organised crime, told the paper: "This is a
very efficient investigation tool."
Toni Stadelmann, head of Swisscom's mobile phone
division, is quoted as saying: "We release the movement
profile of mobile telephone customers on a judge's order."
In Britain, six mobile phone companies are understood to
have arrangements with law enforcement agencies to
provide coding information on individual phones used by
suspected terrorists or serious criminals, but there are
legal and procedural restrictions. As in all intelligence and
police work, according to one intelligence source,
technical surveillance is carried out only for what the
source described as "focused" operations on key
individuals.
"Some people might think the law enforcement authorities
are tracking every mobile phone user, but that is complete
nonsense. We have to have our antennae out to get the
critical leads, but once we've got a lead we focus on that
individual and a lot of effort goes into filtering out
extraneous information."
Earlier this year there was a row in Australia when police
admitted that they were using the mobile phone network
to keep track of known criminals. Signals emitted by the
criminals' phones and picked up by local base stations
were being used to pinpoint people, providing "a very
valuable investigative tool", according to Sergeant Frank
Helsen of the New South Wales Police Service Crime
Data Centre.
The method worked even if the phones were not in use,
since they emit signals automatically every half hour. Data
collected by the phone companies whose base stations
pick up these calls was being reconstructed to pinpoint the
whereabouts of the phone users.
Chris Puplick, the chairman of the New South Wales
Council for Civil Liberties, protested that walking around
with a mobile phone was "like walking around with a
beeper or an implanted transmitter".
In the Australian case, the mobile phone companies said
that they did not routinely keep the data from phones but
would do so if a warrant were issued in advance. The
police service declined to say how often this happened.
In the Swiss case, it appears that the data is automatically
recorded.
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It is true that while a call is in progress the person can be
tracked with standard radio tracking techniques. It is also true
that Phone Companies store the Call Data Record (CDR) for billing
and marketing purposes. Most Telcos now try to store 18 months of
this data (Swisscom will be about 2Tb of info after 18 months). The
CDR contains the base station or cell that was being used (remember
that a user in a car is likely to pass through many cells. Cells
overlap depending on location and may be small (a square kilometer
in a town) or large (fifty square kilometers in open flat
countryside).
But the statement:
"Swisscom [the state-owned telephone company] has
stored data on the movements of more than a million
mobile phone users and can call up the location of all its
mobile subscribers down to a few hundred metres and
going back at least half a year," the paper reports, adding:
"When it has to, it can exactly reconstruct, down to the
minute, who met whom, where and for how long for a
confidential tte--tte."
is totally implausable, we have enough problems with the volume
of CDR data as it is without storing the radio direction info
as well.
It is well known that subscribers may also not be the user, e.g.
a man may be a subscriber twice, but may give one phone to his
wife - so who is using the phone and how do you know that ?
Furthermore Swisscom have a service called 'Natel Easy-Go' where
you can pay cash for a pre-paid mobile phone. Unless the person
pays by credit card to re-charge the prepayment element you
don't even know who the subscriber is !
Finally the Police in most countries do use the CDR information
from Telcos both mobile and fixed line, and in most countries it
is controlled by court order. Even the limited information that
I have described as being available helps catch criminals, who
like all of us are creatures of habit and normally just pick up
the nearest phone !
davidw
