Shed doors are usually mounted with surface-mounted hinges, which are easy to install and strong, but they’re not very secure. If you padlock the doors, someone could just take out the screws and pull the doors right off. The solution is to remove one screw from each hinge leaf and replace it with a carriage bolt. The round head of the carriage bolt prevents someone from using pliers or a wrench to loosen it.
And on the inside of the door, put on a washer and nut and tighten it up. Now, there’s no way someone could unscrew the hinge and bust into your shed.