Patent ID: 8645624

Claim:
A smart card comprising: a data memory that stores data; an important data table that stores an identifier indicating parent data that contains important data; a write unit that writes data to be written to the data memory according to a write command supplied from an external device; a determining unit that determines whether the data to be written contains important data according to whether an identifier of parent data stored in a head portion of the data to be written, specified by the write command, coincides with an identifier of parent data containing important data stored in the important data table; a calculating unit that calculates a head address of the important data in the data memory based on data length from a head of the data to be written to a head of the important data and an address on the data memory at which a process of writing the data to be written is started, upon the determining unit determining that the important data is contained in the data to be written; and a position table that stores information indicating a head address of the important data calculated by the calculating unit in correspondence to information indicating the important data.