| 摘要 |
<p>A network system has: an application server (120, 121) for providing service; a client (102) for using the service; and a key server (103). The client acquires and stores a management cryptographic key, acquires a transaction cryptographic key to be used for a transaction with the application server, encrypts the transaction cryptographic key with the management cryptographic key, sends the encrypted transaction cryptographic key to the key server, requests the key server to send back the encrypted transaction cryptographic key for a transaction, and decrypts the encrypted transaction cryptographic key with the management cryptographic key to acquire the transaction cryptographic key. The key server stores the sent, encrypted transaction cryptographic key and sends the encrypted transaction cryptographic key to the client in response to a request from the client. <IMAGE></p> |
