When the legacy power infrastructure is augmented by a communication infrastructure, it becomes a smart grid. This additional communication infrastructure facilitates the exchange of state and control information among different components of the power infrastructure. An Enhanced Public Key Infrastructure to Secure Smart Grid Wireless Communication Networks As a result, the power grid can operate more reliably and efficiently .Although deploying the smart grid enjoys enormous social, environmental and technical benefits, the incorporation of information and communication technologies into the power infrastructure will introduce many security challenges. For example, it is estimated that the data to be collected by the An Enhanced Public Key Infrastructure to Secure Smart Grid Wireless Communication Networks smart grid will be an order of magnitude more than that of existing electrical power systems. This increase in data collection can possibly introduce security and privacy risks. Moreover, the smart grid will be collecting new types of information that were not recorded in the past, and this can lead to more privacy issues .As shown in Fig. 1, an essential part of the smart grid will An Enhanced Public Key Infrastructure to Secure Smart Grid Wireless Communication Networks be its communication networks. This is a three-tier network which connects the different components of the smart grid together, and allows two-way information flow. The first tier connects the transmission system located at the power plant and the control centers of Neighborhood Area Network (NAN). Each NAN comprises a number of Building Area Networks (BANs) and provides them interfaces to the utility’s wide-area network. Here, BANs are customer networks and belong to the second tier of the shown system. Each BAN consists of a number of third-tier networks, Home Area Network (HANs). The HAN is a customer premises network which manages the on-demand power requirements of end users. Note that there is no standard definition of these networks yet. Their structures described above feature a practical configuration that can be found in established smart grids. An Enhanced Public Key Infrastructure to Secure Smart Grid Wireless Communication Networks While different components of the power infrastructure of the smart grid are networked together to exchange information, as illustrated in Fig. 1, there is a potential increase of the security risk of the system. For example, it will increase the complexity of the electrical power grid, which in turn can increase new security vulnerabilities. Also, the number of entry points that can be used to gain access to the electrical power system will increase when all of the components are networked together. In the remainder of this article, we mainly focus on the security of wireless communication subnetworks of the smart grid. Security in wired links can be achieved by existing techniques such as firewalls, virtual private networks, Secure Shell or other higher layer security mechanisms.