Smart cards communicate with the reader through either the contact plates located on the plastic card or through radio frequency. This may be an error message or just an acknowledgment of the instruction. Like PCs, smart cards have a file system which contains a root or master file. All files are identified by two bytes. The master file on smart cards is identified by 3F 00 .
Dedicated files are similar to sub-directories in that they allow files to have specific paths.
Information is actually stored in what is called the elementary file. The elementary file can be defined in different ways, depending on how the user wants it subdivided for storage. The following diagram shows a simple smart card file system. As smart cards work their way into our lives through cellular phones, stored-value and authentication systems, they will also make their way into our general computing environment. Linux provides a secure multi-tasking environment perfect for smart cards.