Image Number 6 for United States Patent #5448638.
A gasoline service station includes gasoline dispensers and a PIN pad including keypads for receiving personal identification numbers and assembled into a network for securely communicating personal identification numbers from the PIN pads and dispensers to a host computer over unsecured data lines. The PIN pads and dispensers each include means for encryption and outputting of personal identification numbers. A security module includes means for decryption of data associated with each PIN pad and dispenser in a process for the respective PIN pads and dispensers and means for encryption of data associated with the host computer in a process which is different from its decryption of data associated with the PIN pads and dispensers. A site controller, which is not secure from unauthorized signal detection, has means for directing encrypted data received from the PIN pads and the dispensers to the security module and from the security module to the dispensers or the host computer as needed for properly directing encrypted data to a desired destination.