at least one nonvolatile memory device configured to store data; and

a storage controller configured to control the at least one nonvolatile memory device based on a request from the host,

generate a virtual table comprising a plurality of random values, wherein each random value of the plurality of random values designates an index from among a plurality of indexes corresponding to a plurality of main functions; and

transmit the virtual table to the host,

select a target function from among the plurality of main functions and a plurality of sub functions associated with the plurality of main functions, based on the virtual table;

generate a vendor unique command (VUC) designating the target function; and

transmit the VUC to the storage controller, and

parse the VUC based on the virtual table,

perform an operation corresponding to the parsed VUC; and

transmit a result of the operation to the host.