The main goals of smart metering are the reduction of costs, energy and CO2 by the provision of actual metering information to the providers and the customer. They allow for flexible possibilities to influence the customers' energy consumption behavior and to adapt dynamically the power generation and distribution to the requested energy by smart grids. Metering devices are under control of governmental organizations, which are responsible for the permanent correct delivery of metering data. The governmental organizations accept online metering, administration and even software download of regulated software only, if strong, lawful security requirements are fulfilled. This paper describes such a security system. It considers not only the security mechanisms of the metering devices, but also of the complete system hierarchy, which is planned for the communication system of smart metering. It supports also new use cases, which are caused by the liberalization of the energy and metering services markets.