As we are focusing to the new and innovative Smart Grid services provided to the customer domain, security is the essential function which is required to almost all Home Area Network (HAN) devices. Most devices in the customer domain are required to have security function with communication function as basic capability. In this paper we address two issues. First, in order to define the security threats and security requirements for the devices in the customer domain, we need to understand and analyze the operating procedures and information flows for providing new services. We explain the information flows for the major operation scenarios. Second, we address the implementation of security functions in the HAN devices. We explain the general concept of one possible economic and efficient approach to develop the devices based on the multi-core processor and parallel programming model.