There was a startup a while back making a login auth system based on the gait of your walk. Apparently phones' accelerometers are good enough to throw all the data at some ML stuff and uniquely fingerprint people based on how they walk.

This is also the idea behind Google's click-to-confirm-I'm-not-a-robot captcha system... they track everything from how you move the mouse to how you scroll the page to differentiate bots from humans.