采用远程终端方式是减少绿卡工程建设中的投资、加快建设进度、提高网点设备利用率和可靠性的有效途径。而远程终端安全保密性很差。在对线路加密的方法进行了初步的研究和论证后,得出了传统的分组加密法不适用于线路加密,必须采用序列加密法。进而讨论了m序列用于序列加密的可能性,并研究了相应的实现方法。 The use of remote terminal mode is to reduce green card construction investment, accelerate the progress of construction, improve network equipment utilization and reliability of the effective way. The remote terminal security is poor. After the preliminary research and demonstration on the method of line encryption, it is concluded that the traditional packet encryption method is not suitable for line encryption, and the sequence encryption method must be adopted. Furthermore, the possibility of using m sequences for sequence encryption is discussed, and the corresponding implementation methods are also studied.