I have known for many years looking at handoff information on cell networks that it is fairly easy to track a person via their mobile phone.

Although you might be one of twenty or thirty people living in postcode A and working in postcode B (see paper by Philippe Golle and Kurt Partridge http://crypto.stanford.edu/~pgolle/papers/commute.pdf) you generally travel to work by the same route at the same time.

Even when the data is randomized to protect the user the same journey and time tends to nail you cold. If the randomization is incorectly picked, then your subsiquent movments can still be determined with a fair degree of accuracy.

And even if you decide to change your phone by swapping it with a colleague or friend, at some point you fall back into the same regular pattern and therefore you are “found again”.

It is surprisingly difficult to hide a user as an unknown entity if the attendent geoloc and time data is included. The process of making them known is usually simply a DB lookup for unique known patterns (like days you where not in the office or at a known site for a meeting etc).

Phone tracking couldn’t save Holly and Jessica, but it helped to bring their killer to justice.

Ben Elton’s “Blind Faith” would be my suggestion for extended reading on this topic, especially in light of Frank Stajano’s comments.

I’m guilty of losing contact with friends because they didn’t disappear into the internet like i did.

They better do, otherwise they’ll appear suspicious. More at The mobile phone as self-inflicted surveillance.

(This post brings back memories of fingering some badges when I first heard about this project!)

br -d