| 摘要 |
PROBLEM TO BE SOLVED: To provide a shared authentication information update system in which in the case where a plurality of users share one terminal, after one user updates shared authentication information, another user can use the authentication information after the update even when the other user is under an off-line environment.SOLUTION: A sever device capable of communicating with a shared terminal shared by a plurality of users generates a new encryption/decryption key, a new version of an encryption/decryption key used at the shared terminal by a first user of the shared terminal, and identifies a second user that shares the new encryption/decryption key with the first user. The server device obtains secret information, information specific to the identified second user. In addition, the server device encrypts the new encryption/decryption key using the obtained secret information on the second user. The server device transmits the new encryption/decryption key and the already-encrypted new encryption/decryption key, the encrypted new encryption/decryption key to the shared terminal.SELECTED DRAWING: Figure 2 |
