Mediation device, mediation method and mediation system

Abstract

Hiding a service providing server from an authentication server is incompatible with involving the service providing server in the selection of the authentication server. An authentication mediation server () comprises a authentication server reliance condition storage unit () which stores a first identifier to specify at least one service providing server () in association with reliance conditions to authentication servers () in the service providing server (); a user usage authentication server storage unit () which stores second identifiers to specify the respective plurality of authentication servers () in association with a third identifier to specify a user who uses the authentication servers (); a high reliance authentication server calculation unit () which calculates degrees of reliance for the respective authentication servers (), on the basis of the reliance conditions to the authentication servers () which are associated with the first identifier extracted from the authentication server reliance condition storage unit (); and an authentication server selection unit () which selects a second identifier having the degree of reliance which satisfies a previously provided condition, from the second identifiers associated with the third identifier extracted from the user usage authentication server storage unit ().