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Smart Card Standards

ISO 7816: Identification Cards—Integrated Circuit(s) Cards with Contacts provides the basis to transition the relatively simple identification card from a token that can be compromised through forgery, theft, or loss into a tamper-resistant and “intelligent” integrated circuit card (ICC), more popularly known as a smart card. It is a multiple-part standard through which the smart card is specified in sufficient detail to achieve the same level of interoperability that has been achieved with the simpler cards discussed in the section “ISO Standards for Cards.” Although ISO 7816 includes at least six approved parts and has several additional parts under review, the discussion here is limited to Parts 1 through 5:

  Part 1—Physical characteristics
  Part 2—Dimensions and location of the contacts
  Part 3—Electronic signals and transmission protocols
  Part 3, Amendment 2—Revision of protocol type selection
  Part 4—Inter-industry commands for interchange
  Part 5—Numbering system and registration procedure for application identifiers


Note:  
In the ISO standards related to ICCs, the device into which the ICC is inserted is referred to as an interface device (IFD). In the course of this book, the terms ICC, card, and smart card tend to be used interchangeably. Similarly, the terms IFD, reader, and terminal are used to mean the same thing.

ISO 7816-1 extends the physical characteristics definition of simpler ID-1 identification cards from the realm of plastic cards with perhaps an associated magnetic stripe to the more complex environment supporting an integrated circuit chip within the card. This includes accommodation of exposure limits for a number of electromagnetic phenomena such as x-rays, ultraviolet light, electromagnetic fields, static electrical fields, and ambient temperature of the card (with embedded chip), as indicated in Table 3.2.

Table 3.2. Exposure limits for physical phenomena.
Phenomenon Limit

Ultraviolet light Ambient (depends on card vendor)
X-rays Two times acceptable annual human dosage
EMI (electromagnetic interface) No interference with magnetic stripe
Electromagnetic fields Less than 1,000 Oe
Static electricity 1,500 volt discharge through 1.5 K ohm resistor from 100 pF capacitor
Heat dissipation Less than 2.5 watt; card temperature less than 50° C

The specification is also concerned with defining the characteristics of the card when it is bent or flexed. The concern, of course, is that an environment amenable to operation of the chip in the card—with its micro-electronic connections between surface connectors and chip I/O pins, as well as its integrated circuitry—be maintained. Two tests of flexibility for the card are specified. Figure 3.3 illustrates the bending requirements of the card and Figure 3.4 illustrates the torsion requirements of the card.


Figure 3.3.  Card bending testing.


Figure 3.4.  Torsion testing of a smart card.

In the cases of both bending tests and torsion tests, the concern is that through the normal wear and tear on a card (for example, keeping the card in one’s wallet), either the chip itself or the microconnection wires from the chip to the surface contacts will be damaged or broken. Practical experience with these tests has shown that a chip size on the order of 25 mm2 is the largest that can routinely meet these flexibility constraints.

Characteristics of Smart Cards

The mechanical tolerances required of smart cards are relatively stringent in order to ensure that cards can be properly aligned so a reader’s contact points can make a good electrical connection with the correct card contacts. In general, the card’s contacts cannot vary from the surface of the card by more that 0.1 mm. The card must be sufficiently strong to resist permanent deformation when bent; it must be possible to return the card to a flat position with a very modest pressure over the face of the card. Finally, the electrical resistance of the card’s contacts must fall within the acceptable limits established by ISO 7816-1.

ISO 7816-2 specifies an ICC with eight electrical contacts present in a standardized position on the front face of the card. These are referred to as C1 through C8. Some of these contacts are electrically connected to the microprocessor chip embedded within the card; some are not, having been defined to allow for enhancements but unused at the present time. The specific definitions for the contacts are shown in Table 3.3.

Table 3.3. Contact definitions for smart cards.
Contact Designation Use

C1 VCC Power connection through which operating power is supplied to the microprocessor chip in the card.
C2 RST Reset line through which the IFD can signal to the smart card’s microprocessor chip to initiate its reset sequence of instructions.
C3 CLK Clock signal line through which a clock signal can be provided to the smart card’s microprocessor chip to control the speed at which it operates and to provide a common framework for data communication between the reader and the smart card.
C4 RFU Reserved for future use.
C5 GND Ground line providing a common electrical ground between the reader and the smart card.
C6 VPP Programming power connection providing a separate source of electrical power (from the operating power) that can be used to program the nonvolatile memory on the microprocessor chip.
C7 I/O Input/output line that provides a half-duplex communication channel between the reader and the smart card.
C8 RFU Reserved for future use.


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