| 摘要 |
PROBLEM TO BE SOLVED: To prevent a common encryption key from being decoded and to facilitate its management. SOLUTION: This system is provided with a storage section 2, an encryption/ decoding section 8, a user management section 3, a key acquisition section 4, and a key distribution section 5. When the user management section 3 takes part in any channel, the section 3 acquires user information including a nickname list from a chat client and stores it. The key acquisition section 4 selects any user terminal to request an encryption key and stores the encryption key that is sent on request to the storage section 2. Upon the request from other user terminal, the key distribution section 5 distributes the encryption key read from the storage section 2 to the other user terminal. Furthermore, the system is also provided with a key revision section 6 to preferably prevent the key from being decoded by revising the encryption key under a prescribed trigger. It can also be thought that key distribution attribute and key revision attribute are added to user information, and the encryption key is distributed or updated based on the sets of the attribute. |
