| 摘要 |
PROBLEM TO BE SOLVED: To provide a cipher device in which a ciphering key is completely held in secrecy by a data sender. SOLUTION: A cipher device 21 is provided with a data storage device 28 which temporarily stores a session key that is sequentially delivered from a service operation company transmission site being a data distributor side to contractors, stores the system key permanently, stores temporarily the same master key that is given to each contractor solely and stored permanently by each contractor and has a function to store temporarily control information required for ciphering and decoding. Then, a decoding section 29 decodes the ciphered master key and a cipher section 30 uses the decoded master key to cipher the session key for a data receiver side.
|
