US Patent 7266695 Data updating method and data updating system

The present invention provides a data updating method and a data updating system, which can update data of an IC card through a network without mistaking the IC card targeted for updating. When each of issuer client authentication, personal authentication, issuer server authentication and device authentication is performed, a server transmits update data encrypted by a public key used for the device authentication to a client. Then, the client outputs the encrypted update data to an IC card. In the IC card, the update data is decrypted by a secret key used for the device authentication. Based on the decrypted update data, rewriting is carried out in the IC card.