1. A device to use a password by touch-less gesture, the device comprising: two or more ambient light sensors arranged at respective surface locations of the device, each of the two or more ambient light sensors configured to measure light intensity at the respective surface location; a first processor configured to execute a password application on the device; and a second processor configured to detect two or more gestures performed by an object in touch-less communication with the device and define or verify a password based on the two or more gestures.