| 摘要 |
PURPOSE:To make a ciphering method to be used differ for every user. CONSTITUTION:When at a terminal 1A, a ciphering means 2A is given the instruction of a key sharing method, the ciphering means 2A ciphers a common key KS2 by an initial key KS1, and sends this cipher text C2 to the terminal 1A. The terminal 1A sends C2 to the terminal 1B, and the terminal 1B sends C2 to the ciphering means 2B. The ciphering means 2B decodes C2 by the initial key KS1, and obtains the common key KS2. In the terinals 1A and 1B, data is cipher-processed by the common key KS2 by each ciphering means 2A, 2B, and is sent to the terminal, and is sent to an opposite party. The ciphering means 2A, 2B can be exchanged to the terminals 1A, 1B, and another ciphering method can be used by exchanging the ciphering means. The terminal can not know what ciphering program is used. |
