After day of experiments, I realized that there is no need for secure functions. I just did it the wrong way. Code to buy something is:
Code:
C_AuctionHouse.StartCommoditiesPurchase(itemId, qty, unitPrice);
C_AuctionHouse.ConfirmCommoditiesPurchase(itemId, qty);
And, that’s it. You do not need anything else. Thanks for reading.