A computer power supply includes a standby voltage output terminal to output a standby voltage, a power connector connected to the standby voltage output terminal, and a standby voltage discharge circuit including a zener diode, first and second electrical switches. The image forming apparatus includes: plural photosensitive members; plural exposing units opposed to the photosensitive members, respectively, each of the exposing units including a plurality of light emitting elements arranged in a first direction; and a body frame which is provided at both sides of the exposing units in the first direction. A rinse solution is recovered from the contacting. The arm portion and the convex block are located at the same side. A verification of the signature combines a first component derived only from the hidden portion of the message with the visible portion and produces a hash of the combination.