Hi,
The "force SSL on checkout" is an HikaShop setting because the checkout is related to HikaShop.
Be careful to not have the plugin "no ssl outside checkout" published.
After that, I'm sorry but the "login" is provided by "com_users" and that is a native Joomla component.
That login page is not provided by HikaShop.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.