Systems and methods for authorizing a customer premise equipment device to join a network through a network termination unit. The knee pad preferably includes a body that has a generally convex outer surface and a generally concave inner surface. The hydraulic motor is driven by the introduced fluid and drives the hydraulic pump to cause the fluid ejected by the hydraulic pump to be intensified. A determining unit determines a new transmit timing for the target radio apparatus, based on the difference and outputs the new transmit timing determined to the notification unit. The reproduction apparatus decrypts the encrypted media key using a device key to generate a decryption media key, judges whether the decryption media key is the detection information, and prohibits the encrypted content recorded on the recording medium from being decrypted when judged in the affirmative.