Patent attributes
A system, apparatus, method, and machine readable medium are described for non-intrusive privacy-preserving authentication. For example, one embodiment of a method comprises: entering into a legitimate user state on a client device for a time period following an explicit authentication by an end user; recording reference data related to user behavior while in the legitimate user state; measuring user behavior when outside of the legitimate user state and arriving at an authentication assurance level based on a distance between the measured user behavior and the recorded reference data; in response to an authentication request within the legitimate user state, providing an authentication assurance level at or above a defined threshold, the authentication assurance level being sufficient to authenticate the user to a relying party; and in response to an authentication request while outside of the legitimate user state, providing the authentication assurance level based on a distance between the measured user behavior and the recorded reference data.