Hi, is secure.domain.com a mojoPortal child site of www.domain.com? If so, that's an unusual configuration. It's expected that the main site has SSL available, and it may or may not be available to child sites, depending on whether you have a regular or wildcard SSL certificate. The configuration keys are geared toward that type of setup.
If your situation was that the SSL certificate was issued for the main site, and not valid for child sites, you could use
<add key EnableSSLInChildSites = false>
So, if secure.domain.com was the main site, and www.domain.com was a child site, you would be using http://secure.domain.com everywhere except the admin pages and those pages where you've checked the "Require SSL" box in Page Settings, Security (they would be https://secure.domain.com). If you had links to http://www.domain.com, even on SSL-secured pages, they would be left as non-SSL with EnableSSLInChildSites set to false. Of course, all of your forms would have to be located in the secure.domain.com site in order to take advantage of SSL encryption of the pages.
Hope that helps
Jamie