| 摘要 |
PROBLEM TO BE SOLVED: To obtain a network system having a secrecy service function by which unitary key management is executed by enciphering the open key of a call opposite party exchange and a common key for enciphering a message whenever a call requesting secrecy communication occurs and distributing them. SOLUTION: A central management controller 20 and respective exchanges distribute the keys on demand by constituting a network independent of the public line network 22. For example, the exchange SW2 transmits opposite party information to the controller 20 when a call is made. The controller 20 transmits opposite open key and common key information to the exchange SW2 by retrieving a database. The exchange SW2 enciphers common key information by the opposite party open key and transmits it to the exchange SW4 of the opposite party. The common key is obtained by decoding through the use of one's own open key. Therefore, message information is exchanged between the exchanges SW2 and SW4 by enciphering it by using the common key. |
