Seems like that would be the incredibly difficult to train, incredibly invasive and by the time it detected the user probably wasn't you or you weren't nearby t

Seems like that would be the incredibly difficult to train, incredibly invasive and by the time it detected the user probably wasn't you or you weren't nearby to considerable confidence you could have been compromised already. I think that kind of approach would be better handled by implants or wearables like watches with super long battery life but Bluetooth tokens already so most of that with half the invasiveness.