Securing Windows Server Update Services
For synchronization with upstream WSUS servers, you can use Secure Sockets Layer (SSL) protocol to secure the update metadata portion of the synchronization. WSUS can use SSL to:
Enable client computers and downstream WSUS servers to authenticate an upstream WSUS server.
Encrypt metadata passed on to client computers and downstream WSUS servers.
For more information about configuring your WSUS server to use SSL, see Deploying Microsoft Windows Server Update Services.