Patent ID: 8418239

Claim:
A method for authenticating an information processor used as a node among a plurality of nodes in a network, the method comprising: when the information processor is capable of communicating with a node having an authentication function for authenticating other nodes among the plurality of nodes in the network, transmitting by the information processor authentication information required for requesting the node to authenticate the information processor; when the information processor is incapable of communicating with any of nodes having the authentication function among the plurality of nodes in the network, connecting an authentication device carried by a person responsible for installing the information processor to the information processor via a serial interface; obtaining by the information processor first key information of the authentication device from the authentication device via the serial interface and second key information of the authentication device through another route physically different from a route through which the first key information is obtained; verifying by the information processor authenticity of the authentication device based on the first and second key information thus obtained; when the authenticity of the authentication device has been successfully verified, outputting by the information processor the authentication information through the serial interface to the authentication device and requesting the authentication device to authenticate the information processor; receiving by the authentication device the authentication information from the information processor; and performing by the authentication device authentication of the information processor based on the authentication information.