Patent attributes
By enabling to write information which is readable only by an IC card owner on an IC card without inputting a PIN and to authenticate a creator of the written information and prevent falsification, it is guaranteed that data written on the IC card can be read only by the IC card owner, the creator of the written data can be specified, and the written data has not been falsified. A secure memory card 101 includes a card private key storing unit 208 storing a private key, a card certificate storing unit 202 storing a certificate of a public key which forms a pair with the private key, a certificate sending unit 201 sending the certificate to a PC 102, a private storing unit 203 which is readable/writable from the outside only when a correct PIN is input, a public storing unit 210 which is readable/writable from the outside without checking a PIN, a confidential data receiving unit 211 receiving confidential data from the PC 102, and so on.
