This paper presents the results of applying security features to a C-band modem that uses a dedicated frequency of 5091 ~ 5150 MHz for mission data link for unmanned vehicles, and demonstrating the security features while mounting and flying it on a UAV. We implemented the security functions such as mutual authentication and key sharing, high-speed encryption and unmanned vehicles identification required for modem communication by implementing the AES module in the modem’s FPGA and attaching the DSM of the Micro SD type to the modem. And this paper describes the demonstration results of these security functions.