Abstract: An improved enclosure assembly of the type including an openable enclosure, a locking member movable relative to the enclosure for selectively locking or unlocking it, a keeper mechanism mounted on the enclosure for retaining the locking member in its locked position, and a manually operable lock for selectively locking the locking member in its locked position.An improved tamper-proof locking assembly is provided which greatly minimizes the danger of unwanted intrusion into the locked enclosure. A guard housing having a single opening is placed about the keeper mechanism. The single opening of the guard housing is made large enough for the insertion of a human hand therein when it is desired to unlock the manually operable lock, but is made too small for insertion of a cutting instrument that could cut apart either the locking member, the keeper mechanism, or the manually operable lock.