Time synchronization is quickly becoming a fundamental prerequisite for a smart society. With the development of the fifth-generation (5G) network, time-sensitive networking (TSN), and the rise of high-precision networks, its accurate and reliable features have attracted an increasing amount of attention. As the most promising protocol with sub-microsecond accuracy, precision time protocol (PTP) has been widely used for network synchronization, and its proper operation and security are critical to the industries that build the infrastructure for a smart society. In order to provide synchronization security as a service, this paper presents a scheme based on software-defined networking (SDN) and network functions virtualization (NFV) princip...