Abstract: Disclosed are protection of secret information in a system for reporting an emergency such as theft or confinement when secret information is accessed. Secret information includes a large quantity of data and a piece/pieces of true and correct data mixed into the data. The secret data including the data and the true and correct data is two-dimensional code data the code of which is composed of groups of cells having different areas. The positions and order of storage of the true and correct data dispersedly mixed in the data are determined and reported to the user. The user adds a predetermined alerting signal when inputting the password to tell that the user is under control of a third party. The system can detect the alerting signal and know that the user is in an abnormal state, performs normal identification procedures, and takes protection/preservation measures. Part of data is specified as confinement report data and added to the true and correct data.

Abstract: An effective means for system authentication by a user. A system is characterized by connecting an electronic apparatus on the system management side to a terminal on the user side via a communication line including the internet and, using system authentication information recorded on a recording medium included in the electronic apparatus on the system side and personal authentication information entered through a personal input operation on a user-operated terminal, for mutual authentication between the user and the electronic apparatus on the system management side that is accessed. In the mutual authentication system between the user and the system, two sets of authentication data are registered: one set is personal authentication data indicating the personal authentication information on the user and other set is server authentication date indicating the system authentication information.