Patent attributes
A reader/writer that reads or writes information from or in an Integrated Circuit (IC) module, in which one or more applications are loaded, in response to an instruction issued from a controller in which counter-applications compatible with the applications are loaded. The reader/writer includes a memory in which one or more pieces of IC access authentication information that are associated with the applications in the IC module and that are used to authenticate the associated applications respectively are stored. The memory also stores pieces of group authentication information. A control unit authenticates a counter-application using group authentication information and, if the authentication succeeds, permits the counter-application to use IC access authentication information belonging to a group identified with the group authentication information.