A data processing system (DPS) includes a user authentication module that uses a hand recognition module and a gesture recognition module to authenticate users, based on video data from a two-dimensional (2D) camera. When executed, the hand recognition module performs operations comprising (a) obtaining 2D video data of a hand of the current user; and (b) automatically determining whether the hand of the current user matches the hand of an authorized user, based on the 2D video data. When executed, the gesture recognition module performs operations comprising (a) presenting a gesture challenge to the current user, wherein the gesture challenge asks the current user to perform a predetermined hand gesture; (b) obtaining 2D video response data; and (c) automatically determining whether the current user has performed the predetermined hand gesture, based on the 2D video response data. Other embodiments are described and claimed.