Patent ID: 8395797

Claim:
A data storage device for storing changeable data comprising: a storing unit configured to store changeable data; a receiving unit configured to receive an instruction of time certification of changeable data which has been stored in the storing unit, from an information processing apparatus; a time certification request unit configured to request time certification of the changeable data in order to acquire time information to be acquired as a result of time certification, in accordance with the instruction received by the receiving unit; a generating unit configured to add the changeable data with the time information acquired by the time certification request unit and generate data restricted from changing including the time information acquired by the time certification request unit; and a sending unit configured to send the data restricted from changing including the time information to the information processing apparatus, and to send the changeable data which has been stored in the storing unit to the information processing apparatus if the time certification of the changeable data is not instructed.