Identification signal checking apparatus and methods

An identification signal checking apparatus includes an apparatus (1) to be detected having a first wireless transmitting and receiving unit (4) , a first signal processing unit (3) and a first memory unit (5) for storing an identification signal. A detecting apparatus (10) has a second wireless transmitting and receiving unit (11), a second signal processing unit (12), a second memory unit (13) for storing an identification signal, and a random number generating unit (14). When the detecting apparatus (10) receives a response request signal from the apparatus (1) to be detected, the detecting apparatus (10) transmits a random number signal obtained from the random number generating unit (14). When receiving the random number signal, the apparatus (1) to be detected encrypts the identification signal stored in the first memory unit (5) by using the random number signal and transmits the encrypted identification signal to the detecting apparatus (10). The detecting apparatus (10) decrypts the encrypted identification signal and checks whether or not it coincides with the identification signal stored in the second memory unit (13).