Devices and methods calibrate an optical scanner by having the scanner scan a calibration surface. The control system includes moisture and temperature sensors and a means to control the discharge of grain from the grain dryer. A voice recognition portion 20 identifies at least one word from the voice uttered by the viewer based on the voice signal, and acquires them as a keyword. The client queries a central token management system to determine if the candidate token collides with a token generated by or stored at another client.