Abstract: The assembly includes a lock with top hasp and botton keyhole and a flexible, resilient, stretchable covering forming a protective closed casing around the main body of the lock and up through which the hasp protrudes. The casing extends below the lock body and includes a bottom normally closed slit automatically openable by squeezing opposed sides of the lower portion of the casing toward each other at opposite ends of the slit, in order to permit a key to be inserted in the keyhole. The area around the slit can have diverging moisture diverting lips or a single protective overlying lip. Dessicant may be disposed in containers in the casing and the top of the casing can have upstanding collars which tightly grip the hasp. A slot covered with a flap may extend therebetween for removal of the lock from the casing. The casing can be made from natural or synthetic elastomer such as polyurethane capable of retaining its flexibility over a wide temperature range.