Current security protection upgrade of remote terminal units in a distribution automation system is mostly realized by replacing the terminal device hardware board with electricity of the distribution terminal area cut off in the transformation process. An information security encryption module is designed for application by remote terminal units in the distribution automation system. By installing the encryption module in remote terminal units

security protection upgrade of remote terminal units can be carried out without interruption of power supply

nor is it necessary to do any hardware modification and software configuration to the remote terminal units. The operational principle and hardware functions are briefly treated

the validation of remote control message integrity and timeliness

and the authentication process of distribution master station emphasized. The module realizes the integrity protection of remote control message and the identity authentication of the master station

which meets the requirements of the information security protection of the distribution terminal.