Hi,
The HikaShop iVeri plugin is working with that mode (where credit card is entered in your website) because the iVeri payment API does not provide any callback function. HikaShop can't know if the transaction has been made or not, it can't trust the generic "return page" where is no parameter allowing to know that it really comes from iVeri platform.
So, yes it means that you have to use a SSL certificate in your website, like other payment methods which are in "form" mode (instead of "redirect" one).
If you want to use iVeri plugin in classical mode, you won't be able to trust the user for the order validation and you should manually confirm your orders checking the iVeri backend (checking the amount is correct, the order number is correct, etc).
There is no possibility to have an automatic validation otherwise than the method we used.
We know that the implication is to have an SSL certificate but it was the only way.
Regards,