Example apparatus and methods may include: (1) a system and method for enrolling a single user's gait pattern using only accelerometer magnitude data; (2) an efficient and low-power method for continuously generating biometric match scores against the enrolled model at run-time using two phases: detection and authentication; (3) an adaptive method for continuously updating the user model by comparing temporary models generated at regular intervals to the canonical user model; and (4) accelerometer samples captured on a wearable and streamed to a mobile device for further processing.