An integrity checking system includes a tag programming device that generates a plurality of identifiers. Each identifier is associated with either a storage item or an item to be stored by the storage item. The programming device stores each of the identifiers in a plurality of readable tags, each readable tag being adapted to be attached to a corresponding item. A tag reading device reads the identifiers stored in the readable tags and, using only information from the read tags, provides information indicating whether any item supposed to be stored on the storage item is missing from the storage item. Also, methods for storing and reading the identifiers are disclosed along with storing additional information about the items in the tags, such as physical information like weight and/or volume of the items, and then using this information to determine whether any items have been altered.