For the last few months, I have been using self signed certificates to provide ssl for a system that I have been building. We are now getting ready to start getting external users on the system, but this will require purchasing a certificate.
This system will be one of several others that will be running on a sub-domain, but may move to its own domain later on. There will also be several other secured systems running in a similar fashion.
We would also like to put our main site on ssl only too.
So, although I know I can use a wildcard certificate, could I purchase an ssl certificate for the main site, then create a signing request for the sub-domain, and sign it with the purchased certificate, and would that validate for visitors to the sub-domain?