Salami has to breathe, but it mustn't dry out. That is precisely the reason that butchers and delicatessens store their salami by hanging it from racks. To prevent it from drying out at home, you should wrap salami in butcher or wax paper. A lesser preferred alternative is to wrap it in a plastic bag or container. The best thing to do is vacuum seal it to evacuate all the air from inside the plastic bag, and it will remain in good condition for longer.