| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication system capable of securely and easily updates digital certificates used for authentication even when the valid term is expired. SOLUTION: A communication apparatus provided with a communication means and which uses the digital certificates to authenticate a communication party in the case of communication, uses two kinds of the digital certificates with different valid terms for the authentication, authenticates the communication party by using a rescue public key certificate whose valid term is longer than the other (S106), acquires a regular public key certificate with the shorter valid term when the authentication is successful and transmits it to the communication party (S110). In this case, when the communication apparatus makes a communication request to the communication party, the apparatus first uses the regular public key certificate to authenticate the communication party (S102) and carries out the authentication using the rescue public key certificate when the authentication using the regular public key certificate is failed. COPYRIGHT: (C)2005,JPO&NCIPI
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