Mutual for reporting a theft in an authentication system

摘要

Disclosed are protection of secret information including an encryption key and a system for reporting an emergency such as theft or confinement when secret information is accessed. Secret information includes a large quantity of decoy data and a piece/pieces of true and correct data mixed into the decoy data. The secret data including the decoy 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 decoy 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 decoy data is specified as confinement report data and added to the true and correct data. Consequently at least a piece of confinement report data is included and therefore the user himself is judged to be under control of the third party. Then the user is identified and a confinement report alert is issued.