A secure cartridge-based storage system includes a set of read/write control electronics on a shared controller adapted to removably couple with each of a plurality of storage cartridges. Data blocks within primary non-volatile memory of the cartridge-based storage system collectively comprise a main store with information-theoretic security. The shared controller incorporates various controls for providing selective data access to individual data magazines and/or cartridges as well as for partitioning user data and writing the partitioned data according to an information-theoretic security scheme and reading the partitioned data and reconstructing the user data from the partitioned data.