COMMUNICATIONS SYSTEM, CLIENT TERMINAL, SERVER, DATA COMMUNICATIONS METHOD, AND DATA COMMUNICATIONS PROGRAM

摘要

In order to reduce damage caused by identity fraud in network communications, a data communications method is provided, for a data communications system including a server (10) that sends data and a client terminal (20) that receives the data sent by the server, via a network (50), said data communications method preventing identity fraud by including: a transmission step in which the time at which previous communications with the server occurred is used as an encryption key, the current communications time and the previous communications time are encrypted, and the encrypted encryption data is sent to the server; and a decryption step in which the server receives the encryption data sent from the client terminal and decrypts same, using as a decryption key the previous communications time for the client terminal, retrieved from a storage means.