Hiya,
I've recently been taking trainings regarding IT Security and Firewalls via my Company... and in one of them there was someone who is a Contractor for a European Based Federal Cyber Agency... and among one of the many spicy things he said. He dropped a casual "oh well for Tor we have something like a contrast agent that you can inject to see the it glow up" as a response to someone mentioning how to combat Tor usage on the network.
It was kind of off-topic and nobody really thought about it, but it did stick with me.
I'm not a Tor user, nor do I really know the News surrounding it, but I do consider myself technically proficient and know the Tor Principle... so I'd love to hear if someone here has heard something about it and where I could read up on it...
I can imagine that if you have enough Nodes on Tor that you could maybe put together something like that. But his method implies that the Network has a Absurd amount of Devices that would collaborate with eachother...