Sharing Authentication a Sharepoint Portal and MVC Web Application

I have a Sharepoint 2010 portal where users can access a variety of apps, I am attempting to have the portal be a single-sign on using forms authentication for all the apps. Currently users sign into the portal, then when they open one of the apps they have to enter the same credentials again to sign into the individual apps. I did some reading on this and read that if I put this into my web.config (both portal and app) the credentials should be shared:

<forms loginUrl="~/auth/login"
             timeout="720"
             name=".MYCOOKIE"
             domain="mydomain.ca"
             protection="All"
             path="/"
             requireSSL="false"
             enableCrossAppRedirects="true"/>

<machineKey validationKey="myvalkey" decryptionKey="mydeckey" validation="SHA1" />

My understanding is the credentials would be stored in .MYCOOKIE when a user logs into the portal, then opens one of the apps the cookie should provide the authentication data to the app and the user would automatically get signed in. It doesn't work, users still have to sign in...am I missing something?? It appears the issue is on the sharepoint portal end, when I check HttpContext.Current.User.Identity.IsAuthenticated is returns false. These are SSL sites, not sure if that changes anything. Thanks in advance.