SSL Certificates and Redirection

If a website is being redirected, does the original domain name need to have an SSL certificate, or the redirected domain name or both?

Solution 1:

Both, because the redirection is an HTTP-level thing which happens inside the SSL envelope. The client needs to establish an SSL connection to the original host name before it sees the redirect, then after following the redirect it must establish another SSL connection to the target host name.

If you're redirecting between the www and non-www forms of the same domain, it's often the case that one certificate will cover both (using the "subject alternative name" mechanism). For example, I have a site with a certificate from RapidSSL, and when you ask them for a certificate securing www.example.com they automatically issue it with a SAN for the plain example.com form included. I have a single Apache HTTPD with two name-based virtual host definitions on the same IP address pointing to the same certificate.