Abstract: A portable security enclosure assembly is provided for use with a vehicle of the type having a surface. The enclosure includes a base and means for fixing the base to the vehicle surface. Means are provided for detachably mounting the enclosure to the base. The mounting means includes first and second rings pivotally mounted on the base surface for movement between an upright position and a non-upright position. The rings are spaced apart. The enclosure has first and second openings adapted to align with the rings, respectively, when the enclosure is situated on the base, such that the rings extend through the openings in the enclosure when the rings are in the upright position. A locking bar, longer than the distance between the rings, is adapted to be simultaneously received through the rings, so as to secure the enclosure to the base.