| 摘要 |
PURPOSE:To assure the protection of message secrecy by enabling identification at the receiver side even if a charge is given to any area of a cooded message just by adding a signature code to a final message block. CONSTITUTION:A signing device 4 is provided at the transmitter side of a communication line 1 together with another signing device 5 set at the receiver side respectively. A message M which is transmitted to the receiver side from the transmitter side via the line 1 is divided into (n) units of message blocks m(1)- m(n) containing a prescribed number of bit respectively. A signature code (s) is contained only in the final block m(n). While a collating circuit 12 of the device 5 collates a reproduction signature code (s') contained in a reproduction message block d(n) with the code (s). Then a coded message Y receives no change at all if the coincidence is obtained from said collation. While the message Y receives some change if no coincidence is obtained from the collation. Thus it is decided that a reproduced message D different from the message M is delivered. |
