Abstract: Tables (FIGS. 11 and 12) for stipulating information (WWN: WorldWide Name) for primarily identifying computers, information (GID: Group ID) for identifying a group of the computers and a logical unit number (LUN) permitting access from the host computer inside storage subsystem, in accordance with arbitrary operation method by a user, and for giving them to host computer. The invention uses management table inside the storage subsystem and gives logical unit inside storage subsystem to host computer group arbitrarily grouped by a user in accordance with the desired form of operation of the user, can decide access approval/rejection to the logical unit inside the storage subsystem in the group unit and at the same time, can provide the security function capable of setting interface of connection in the group unit under single port of storage subsystem without changing existing processing, limitation and other functions of computer.

Abstract: An IC card and a method thereof for adding or changing a program for a memory for writing without adversely affecting the function of the IC card and by keeping the security of a program to be written later by restricting writing by a write control program having a decryption function or a program code conversion function.