Using Bluetooth to detect potential contact + plus GPS seem like a good way to cover a lot of ground. Anyways I feel like the bigger issue is the huge honeypot problem. I think it's easier to assume data like this is bound to leak -- so what can we do to make it useless besides for its intended purpose? I mean it doesn't have to protect against like a state backed program to track an individual -- but it should protect against the usual bullshit companies like insurance or scammers.... hmmm