SYSTEM, SERVER DEVICE, CONTROL METHOD, AND PROGRAM

PROBLEM TO BE SOLVED: To provide a system and the like suitable to prevent a fraudulent act, such as alteration of data.SOLUTION: A terminal device includes: a parameter storage part storing parameters; a reception part receiving instruction input; an update part updating parameters based on instruction input; a request transmission part transmitting a request to which parameters are designated to a server device 200 at appropriate timing; and a response reception part receiving a response from the server device 200. The server device 200 includes: a request reception part 201 receiving a request; a request storage part 202 accumulating and storing the parameter and the request reception time; an accumulation part 203 accumulating parameters, or the like when the parameters and a recently stored parameter are within a prescribed range; and a response transmission part 204 transmitting a response designated by a parameter on which a penalty is imposed when the parameters are not present within the predetermined range. The update part performs update by a parameter designated by the response.