Is zero-effort computer security a dream? – Help Net Security

In the ZEBRA system, every user is required to wear a Bluetooth-enabled bracelet, similar to a Fitbit, and the system knows who is wearing which bracelet. When the user logs into a device the first time, the system establishes a secure connection to the bracelet. While the user interacts with the device, the bracelet will send the measurements generated by the interactions over to the device. The device then uses a machine learning classifier to map those actions into a sequence of predicted interactions.

Source: Is zero-effort computer security a dream? – Help Net Security