A gait authentication system and method is provided. The system includes a mobile computing device configured to be carried by a person while moving with a unique gait. A first sensor (e.g. an accelerometer) is carried by the mobile computing device and generates a first signal. A second sensor (e.g. a gyroscope) is carried by the mobile computing device and generates a second signal. A gait dynamics logic implements an identity vector (i-vector) approach to learn feature representations from a sequence of arbitrary feature vectors carried by the first and second signals. In the method for real time gait authentication, the computing of invariant gait representations are robust to sensor placement while preserving highly discriminative temporal and spatial gait dynamics and context.