The Infrastructure Security is an IT area that involves a lot of different technologies and implementation techniques. The same thing can be applied to the XenDesktop architectures. As seen earlier, secure connections can be realized using a secure gateway located in front of the entire VDI architecture. The implementation of a strong authentication method is another important step to perform. In this chapter, we will discuss the use of hardware devices (such as Smart Cards or PKI tokens and special USB keys used to authenticate users), in order to perform the login phase through the use of a valid certificate. Then, we will discuss how to configure a two-factor authentication with software tokens. At the end of this chapter, we will discuss the implementation of the strong authentication logon method, a more robust and secure way to manage the user logon phase, by the use of the Radius platform.