Buckinghamshire CC ANPR cameras

[Roland Perry]

In article 
<CAJkBBXVdM41CaWi9dDGouvkft3U9TqkQXkJN7p3Rx0pMYi9iug at mail.gmail.com>, 
John Wilson <tugwilson at gmail.com> writes
>It seems clear that this method as a very poor way of anonymising the
>data. If I had access to the data

Which raises the issue of what form of data loss the anonymising process 
regards as a threat. Having scooped up all the data form a central store 
is not the same as eavesdropping the feed from one camera.

>I could easily identify and
>individual's car with out knowing anything at all about the hash
>function other than it always produces the same hash given the same
>number plate. I just need to know the precise time they pass one or
>more cameras

Although if the camera's on a busy road, you may have several cars to 
choose from.

>or less precise information on several journeys.

Two samples should reduce the number of cars in both places at the same 
time to a very small number.
-- 
Roland Perry