Force Subdomain to secure.domain.com rather than domain.com/secure

I have an SSL cert on a subdomain we have (secure), however if someone attempts to access the folder using this method:

http://www.domain.com/secure or https://www.domain.com/secure

It shows the SSL error "ssl_error_bad_cert_domain" which is correct, so what I wanted to do was prevent anyone accessing the secure folder directly, instead forcing them to:

https://secure.domain.com

Which then ensures the SSL cert works correctly.

I am assuming this can be done using the开发者_如何学Go .htaccess file in the subdomain folder (which already forces it to use https), but I'm just not sure how to accomplish it.

Many thanks.

Update 1

Including current subdomains .htaccess

RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

You won't be able to redirect from https://www.domain.com/secure/, because it will attempt to validate the certificate before it attempts any redirect. You'd need a valid certificate covering "www.domain.com" for that to work.

To cover http://www.domain.com/secure, you can use the following.

Redirect 301 /secure/ https://secure.domain.com/