| 摘要 |
PURPOSE:To prevent the encrypt key from leaking to the operator by providing several units of the encrypt key memory to the coding and/or decoding device in the data communication and then carrying out the coding and/or decoding with the keys extracted selectively. CONSTITUTION:Key memories 12 and 20 can store several units of the encrypt key; the fixed key is read out at the access circuit and based on the key identification information to be supplied to encrypt circuit 9; and the key (identification) number is given to the output selection gate. The data supplied is set to interface 6 and buffer 7, and flag monitor part 8 detects the starting and terminating ends of the significant message and then send them directly to gate 10. The significant message is coded at circuit 9 and then supplied to gate 10, where the flag, key number and encrypt signal are sent in that order to circuit 5. At the reception side, the message is decoded via the key number and the fixed encrypt key. |
