Buckinghamshire CC ANPR cameras

James Firth james2 at jfirth.net
Wed Jan 11 11:52:54 GMT 2012

Brian Morrison wrote:
> Mark Lomas <ukcrypto at absent-minded.com> wrote:
> > I remember a police officer explaining the investigation of a
> kidnapping.
> > The kidnappers used a PAYG phone that was only switched on while
> making
> > ransom calls, never used to call any other phones, and taken to a new
> > location each time it was used. Consequently neither an intercept nor
> > traffic analysis would reveal information the police didn't already
> have.
> >
> > Instead the police took the lists of all other phones in the same
> cells at
> > the times of the calls (the data James mentioned) and looked for
> phones
> > that were nearby on more than one occasion.
> So the disciplined kidnapper needs to ensure that any personal phones
> are switched off and that they have a number of other PAYG phones to
> use for other calls which they dispose of carefully after use and
> have only topped up with cash at places without CCTV.

Switching off a phone which is normally otherwise on could also be a
giveaway, assuming MNOs are able to provide lists of phones de-registering
in any given time frame.

An attacker would be better yanking the battery than switching off, as this
doesn't de-register the phone and has a similar signature to driving out of
range (or is at least harder to spot).

Of course the best option would be to leave own phone at home (an even
better option being not to kidnap anyone in the first place).

I wonder if any civilian network implements the "Ambience Listening" feature

James Firth

More information about the ukcrypto mailing list