It’d be interesting to get some technical detail on how they are tokenizing. fundamentally they must assign the same token, as the purpose of the system is not just tracking station occupation but also tracking occupation through the network.
For example, when they see my device enter the network at a station in the morning, they see my device pass through a number of stations, dwell in a station as I change lines (I’m also assuming that looking at which AP receives my probe the strongest they can tell my journey through the station, to the platform, and work out which end of the platform I stand on) then through a few more stations to my destination.
(so they got “in time” data…)
In the evening when they see my device enter at the final station, they can reasonably assume I’m going back to the station I started at, so they’ll know. we currently have 3000 people at Oxford Street, and this guy changed at Oxford street this morning,
Also, it’s actually beneficial to check past journeys also and say the owner of this device always changes at oxford street. (e.g. there is a high possibility they will add to station congestion.
-then they can see significant station crowding issues that are about to happen, and slow the trains, or half the trains, in the tunnels waiting for platform congestion to clear. (i.e not just about an individual, it’s about the movement of masses.)
(changing the method used to create anonymity daily would provide more privacy, but also lessen the functional use to the network. - e.g. can’t check journey history.)
But it is more than that.
It’s consistently using the kill switch where you are. (not just when travelling.)
It is not connecting to “public” networks, not connecting to work networks,
Regularly purging your remembered connections. etc.
it’s changing your home networks to not advertise SSID presence so that if you are out, your home network names are not exposed. - and then accepting that you can’t use certain devices that might
require the SSID to be visible (e.g. cheap wifi light bulbs.)
There isn’t a cheap trick to privacy or security, hardware kill switches are one part of what for most would be a significant lifestyle change to achieve true security.
For many, (myself included!) this kind of cost of privacy feels like a high price.