A smart card may have the following generic characteristics:
- Dimensions similar to those of a credit card. ID-1 of the ISO/IEC 7810 standard defines cards as nominally 85.60 by 53.98 millimetres (3.37 in × 2.13 in). Another popular size is ID-000 which is nominally 25 by 15 millimetres (0.98 in × 0.59 in) (commonly used in SIM cards). Both are 0.76 millimetres (0.030 in) thick.
- Contains a tamper-resistant security system (for example a secure cryptoprocessor and a secure file system) and provides security services (e.g., protects in-memory information).
- Managed by an administration system which securely interchanges information and configuration settings with the card, controlling card blacklisting and application-data updates.
- Communicates with external services via card-reading devices, such as ticket readers, ATMs, DIP reader, etc.
Contact smart cards
Contact smart cards have a contact area of approximately 1 square centimetre (0.16 sq in), comprising several gold-plated contact pads. These pads provide electrical connectivity when inserted into a reader, which is used as a communications medium between the smart card and a host (e.g., a computer, a point of sale terminal) or a mobile telephone. Cards do not contain batteries; power is supplied by the card reader.
The ISO/IEC 7810 and ISO/IEC 7816 series of standards define:
- physical shape and characteristics
- electrical connector positions and shapes
- electrical characteristics
- communications protocols, including commands sent to and responses from the card
- basic functionality
Because the chips in financial cards are the same as those used in subscriber identity modules (SIMs) in mobile phones, programmed differently and embedded in a different piece of PVC, chip manufacturers are building to the more demanding GSM/3G standards. So, for example, although the EMV standard allows a chip card to draw 50 mA from its terminal, cards are normally well below the telephone industry's 6 mA limit. This allows for smaller and cheaper financial card terminals. Communication protocols for contact smart cards include T=0 (character-level transmission protocol, defined in ISO/IEC 7816-3) and T=1 (block-level transmission protocol, defined in ISO/IEC 7816-3).