A device for entering the detonation codes for nuclear weapons.
The code system utilizes the President's biometric data. It is keyed to the President's internal nanomachines, DNA data, pulse, brainwaves, and blood pressure, and can only be activated by direct input from the President himself acting of his own free will. If drugs or threats are used to force the President's hand, the system will detect this and reject the input. It also rechecks the ID at regular intervals after the codes are entered, meaning that if the President dies, the nukes can no longer be launched.