| 摘要 |
PROBLEM TO BE SOLVED: To disclose or change information for a specific session control server. SOLUTION: An encryption key used for encrypting transmitting information by a communication system 302-1 is encrypted by a public key of a specific session control server 301-1 or 301-2, to which information is disclosed, and the information is transmitted along with information encrypted with the encryption key. In the session control server 301-1, which received the signal, the encryption key is encrypted with the public key of the following stage session control server 301-2 or a call termination user's transmission system 302-2 after referring to or changing if needed, and then the information is transmitted along with information encrypted with the encryption key. A pre-shared key can be also used, instead of public key, as the key used for encrypting the encryption key. COPYRIGHT: (C)2008,JPO&INPIT
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