US Patent 8364961 Appliance authentication system, and method of controlling power supply

Provided is a method where a power management apparatus (a) acquires, from a server managed by a manufacturer of an electronic appliance, a public key paired with a secret key that the electronic appliance and the server hold, (b) generates a ciphertext by generating a random number and encrypting the random number by the public key, and (c) transmits the ciphertext to the electronic appliance and the server, where the electronic appliance (d) restores the random number by decrypting the ciphertext transmitted in (c), (e) causes an electrical part to operate, based on the random number, and (f) transmits to the server the value of current flowing through the electrical part, and where the server (g) restores the random number by decrypting the ciphertext transmitted in (c), (h) calculates the value of current to flow through the electrical part based on the random number, and (i) compares values of current.