An optical head for reproducing information contained on an optical information disk includes a plurality of light sources and a plurality of light receiving elements in correspondence with the plurality of laser light sources. Data is encrypted using a session key, and at least one PUF value is generated from a PUF. When the main control unit drives the control line to a \u2018L\u2019 level for a certain period of time or more, the peripheral modules detect that and carry out a hardware reset for itself.