Abstract: A method for unlocking a device, comprising projecting, via a light signal projection unit, a plurality of light signals sequentially on a three dimensional (3D) target object, capturing, via an image capture unit, a plurality of images of the target object dynamically, wherein the plurality of images correspond to the sequence of light signals, constructing a 3D feature representation of the target object from the plurality of images, computing a matching score by comparing the constructed 3D feature representation to a reference 3D data set associated with an object that is approved for unlocking the device, and determining to unlock the device when the computed matching score exceeds a pre-determined threshold.