The semiconductor device of the invention includes a circuit and a protecting structure. It is provided with a first and a second security element and with an input and an output. The security elements have a first and a second impedance, respectively, which impedances differ. The device is further provided with a measuring unit a processing unit and a connection unit. The processing unit transform any first information received into a specific program of measurement. Herewith a challenge-response mechanism is implemented in the device.