One of the questions that always come up during the planning phase of WSUS is how to secure the communication between WSUS and the clients. The general guidelines for this deployment are documented at Securing
WSUS with the Secure Sockets Layer Protocol article and you should always read it first. The goal of this article is to extent this list and highlight additional considerations that you should take while planning this type of deployment.
Consider the Algorithm and Certificate Key length of the certificate you are using: