An electromagnetic actuator includes a coil, which is formed in an annular shape, a plunger, and a stator, which receives the coil inside the stator and forms a magnetic circuit along inner and outer circumferences of the coil through the plunger. A light receiving element row is connected to the other end of the first light receiving element to supply electric power to the first light receiving element. By encrypting a relatively large amount of secret data with a master encryption key, and storing said master key in this non-preferred state storage, the electronic module conveniently extends this protection scheme to a large amount of data, without the overhead of investing or actively erasing the larger storage area.