I have a relatively inexpensive car cover. It has, as most car covers, plastic eyelets on each side for attaching a (security?) locking cable. Never used a locking cable to secure the cover.
My method of keeping my cover on, even in a stiff breeze, is inexpensive but very effective. I use two 10" bungee cords...
...and connect them by tying a 24" piece of cord between them. Once the cover is on the car, I attach one bungee hook (red for demonstration purpose)) into the cover eyelet and toss the other attached bungee (green for demonstration purpose) underneath the car to the other side, then put that hook into the plastic eyelet. On first fitment, adjust the tension between bungees by shortening the cord distance between bungees (it doesn't take much tension to keep the cover on in a stiff breeze).
When bagging the car cover for stowing, I also keep my bungee attaching device in the bag as well.
Hopre you find this info helpful.