| 摘要 |
PROBLEM TO BE SOLVED: To initially write data that a person other than a user should not know safely by decoding ciphered and written data in an IC card. SOLUTION: A secret key C is written in the nonvolatile memory (EEPROM) of an issued IC card and a decoding command for decoding the secret key C is written before or after that. The decoding command is generated by adding a data part to the classification, instruction, and parameter of the command and information on a common key is embedded in the parameter or data part; when the decoding command is activated by some means, the secret key C is decoded by using the common key, so that the secret key A is decoded in the IC card safely. The decoding of the secret key is carried out by reading the decoding command and decoded secret key C out of the EEPROM to a CPU 2a, putting the results back in the EEPROM, and thus rewriting the secret key C. |
