A method for providing a brain computer interface that includes detecting a neural signal of a user in response to a calibration session having a time-locked component and a spontaneous component; generating a user-specific calibration model based on the neural signal; prompting the user to undergo a verification session, the verification session having a time-locked component and a spontaneous component; detecting a neural signal contemporaneously with delivery of the verification session; generating an output of the user-specific calibration model from the neural signal; based upon a comparison operation between processed outputs, determining an authentication status of the user; and performing an authenticated action.