Patent US 4,528,442

A personal identification system capable of using the information of a combination of certain questions and answers to said questions as the information to connect a card to its original owner, capable of displaying said questions at the time of card input and letting a card user enter answers to said questions displayed, and capable of making the use of said card effective upon coincidence between said answers entered and answers selected and registered in advance by an original owner of said card and of invalidating the use of said card upon uncoincidence between said answers.