| 摘要 |
PURPOSE:To encipher call information without transmitting any special key code by performing a specified arithmetic operation for a peculiar identification number, and enciphering the call signal as considering the operated result to be the key code. CONSTITUTION:The identification number (receiver ID) 1 allotted to a receiver preliminarily for the purpose of call is made to be a standard, and scramble processing 2 using specified algorithm is performed for it, and as considering the result f(ID) to be the key code, the call information M is enciphered 3. Accordingly, an enciphered output C comes to be the function of f(ID) and M, and it can be enciphered by the key different for every subscriber. Although there is the possibility of the leakage of the receiver ID itself to a third party, as far as the algorithms of the scramble processing 2 and the enciphering processing 3 are kept secret, there is no fear that the call information is tapped by the third party. Thus, a transmitting side can transmit the enciphered call information by high reliability even without transmitting the special key code. |
