Login authentication system, service provider and authentication server in login authentication system, service provider in login authentication system, authentication server, computer and login authentication method and program for portable terminal

摘要

PROBLEM TO BE SOLVED: To provide a login authentication system in which a service provider together with an authentication server can safely login a service with high confidentiality without requiring for a user to input an ID and a password.SOLUTION: A service provider and an authentication server sequentially perform, on the basis of a login request received from a first user terminal, signature generation and verification by the first user terminal, signature generation and verification by the service provider, signature generation and verification by the authentication server, and signature generation and verification by a second user terminal, and thereby performs login authentication of the first user terminal. If the login authentication is a success, screen information indicating the success of login is transmitted to the first user terminal.SELECTED DRAWING: Figure 7