SERVER SYSTEM, COMMUNICATION SYSTEM, COMMUNICATION TERMINAL DEVICE, PROGRAM, RECORDING MEDIUM, AND COMMUNICATION METHOD

摘要

[Problem] To provide a network system, etc., which improves security and prevents illicit use when providing services such as Internet banking services. [Solution] Provided is a network system which has a configuration of issuing in advance to a user a random matrix table (RMT) which associates text characters which a user inputs with an image such as a photograph which is unrelated to the text characters, and of a financial institution server (30) managing random matrix table data corresponding to the random matrix table (RMT), distributing data for input including a portion of the random matrix table data to a communication terminal device (10) when information is inputted, and executing a specification of information to be specified while comparing the data for input with the random matrix table (RMT).