| 摘要 |
PURPOSE:To change a cipher key during communication without interrupting the communication. CONSTITUTION:A synchronizing signal including a special pattern is transmitted from the transmission side, and a synchronizing signal 2 indicating that frame synchronism is established is received from the reception side, and the number of frames from the current frame to the start of a superframe is transmitted by a synchronizing signal 3, and a synchronizing signal 4 for confirmation which indicates the reception of this signal 3 is received. Thereafter, a cipher key is designated and transmitted, and its reception is confirmed, and a key change timing is transmitted as a preceding frame position in the superframe, and its reception is confirmed, and the cipher is switched to another cipher based on this designated cipher key at this change timing. |
