Background to this question: I want to host multiple e-commerce sites on the same server, each with their own separate customer login application. Each site's login application needs to be secured by SSL. I'm unsure how best to handle this. For example, do I need to acquire a separate SSL certificate for each site (in which case, how do I do this dynamically, as the sites are created), or do I handle this using ONE login gateway-style application, which handles it on behalf of all the sites via a kind of transparent redirect?

I'd be grateful for any pointers or advice. Thanks.