An apparatus, system, and method for avoiding unexpected exposure of important data in a storage system include a table that contains permission and conversion information regarding data transfer. When a storage system transfers a certain set of data from one logical device or volume to another area, e.g., a host, a tape storage or another logical device or volume inside or outside of the storage system, the storage system refers to the table to determine if transfer is permitted and whether conversion of the data is required before transfer. A storage controller converts the data if necessary, and transfers the data to the target destination if permitted. Keys are maintained within the storage system so that the management of securing data is centralized.