StartSSL Certificates for WebUI
I use my wildcard (class 2) cert from startssl.com in my WebUI.
Just as you need to do with nginx, you must concatenate your cert, the class 2 intermediate and root ca certs into a single file with the DECRYPTED key as the key being used. So, to set up your own certs in the WebUI…
System => Cert Manager
===> Certificates Tab
Add a new certificate. For the first field (certificate data), first paste YOUR servers certificate. Then, paste in the Class.x certificate from startcom. Then, below both of those, paste in the root.ca certificate for startcom. In the second field, paste in your DECRYPTED key, save the form and you're done.
Note: The intermediate and root CA's can be found in your startssl tool box, under the TOOLS tab => "Startcom CA Certificates"
Then, go to
System => Advanced
And select the certificate that you added and let it take affect. That's it, done :)