"Out of Home Advertising": the billboards that spy on you as you move through public spaces

[RickMycroft]

That’s what I called it when I thought of it. (Named after radar chaff.) It seems obvious, so someone’s probably thought of it too and called it something else.

The London Underground thinks it can sell travelers' attention and wifi data for £322m

I wonder what would happen to their collection system if there were many people carrying “chaff boxes” that continually pinged with random MAC addresses? (A Pi ZeroW with a battery could do the job.) Alternately, rather than random MACs, listen for phones checking for APs and add those MACs to a list, then use that list to spoof AP checks. As soon as the phone and chaff box parted ways, the tube tracking system would see the phone in multiple locations, rendering their data fuzzy. I mean, if p…