At its core, decoding a smartcard means extracting the raw data stored on its chip. A standard 13.56 MHz smartcard (like MiFARE Classic, DESFire, or iCLASS) stores data in and blocks . Decoding translates that binary or hex data into human-readable values: facility codes, card numbers, expiration dates, or even custom payloads.
A smartcard decoding program is specialized software designed to intercept, interpret, and present the raw communication data between a smartcard and a terminal (card reader). Unlike a simple hex editor, a decoding program understands the Application Protocol Data Unit (APDU) structure.