To improve secrecy of data relating to authentication of a telegram.

An authentication service providing method provides a service relating to user authentication between a user and a member shop in a center device 1 connected to at least one or more pieces of user equipment 3 and at least one or more pieces of member shop equipment for providing services relating to online shops to users via a network. The disclosed method includes a location information selection step of selecting, by the center device, a plurality of position information relating to the position of authentication data in a telegram, regarding authentication, transmitted from user equipment to member shop equipment based on user identification information, for identifying the user, contained in a request from the member shop equipment; and a position information transmission step of transmitting, by the center device, the position information selected in the position information selection step to the member shop equipment 2 of a request source and to the user equipment 3 relating to the request.

COPYRIGHT: (C)2007,JPO&INPIT