Firefox warning messages for SSL "Checkout" and "Confirm order" forms

Hello,

I have ubercart installed and SSL activated for the cart, checkout pages.

When I want to click on "Checkout" or "Submit order" in Firefox, a warning message pops up. I am using the German version of Firefox, so I cannot tell exactly how it is in English, but in German it is

"Obwohl diese Seite verschlüsselt ist, werden die von Ihnen eingegebenen Informationen über eine unverschlüsselte Verbindung gesendet und können leicht von Dritten gelesen werden."

which means

"Although this page is encrypted, the information you have entered will be submitted via an non encrypted connection and could easily be read by a third party."

Now, my webshop cannot go online with such a warning message to the user (hence I indicated 'critical'). I read that the issue is that the checkout and order detail forms don't have conn=ssl included in the html. E.g. instead of

form id="uc-cart-view-form" method="post" accept-charset="UTF-8" action="/cart">

it should be

form id="uc-cart-view-form" method="post" accept-charset="UTF-8" action="/cart" conn="ssl">

Now, I start looking for the form in uc_cart.module and found uc_cart_view_form in the code. However, since this is PHP I have no clue what I have to do in order that in html conn="SSL" will be added.

Can anybody help me with this?

Thanks a lot.

Cheers,
Roger