Single sign-on system and single sign-on method for a web site and recording medium

摘要

A user authentication proxy 2 provided between a user terminal 1 and a web server 4 saves therein information associated with a sequence of user authentication processes between the user terminal and a web server performed by a user. This information includes a web site URL, data received by the user terminal from the web server for user authentication, and data sent by the user terminal to the web server for user authentication. When the user specifies the URL of a web site from any user terminal, the proxy compares data on the URL received from the web server specified by the URL with received data saved in the proxy. If they match, the proxy does not send the data from the web server to the user terminal but sends user authentication operation sending data to the web server on behalf of the user terminal.