22-04-2011, 04:57 PM
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Introduction:
The smart card is one of the latest additions to the world of information technology. Similar in size to today's plastic payment card, the smart card has a microprocessor or memory chip embedded in it that, when coupled with a reader, has the processing power to serve many different applications. As an access-control device, smart cards make personal and business data available only to the appropriate users. Another application provides users with the ability to make a purchase or exchange value. Smart cards provide data portability, security and convenience.
Smart cards today achieve much more than their original application of replacing cash and coins. Smart cards grant access to secure areas, confirm a person’s identity via biometrics, and retain large quantities of personal data (such as medical records.) More important than these specific applications are the recent trends in how the smart cards are used – to facilitate the exchange of information between customer and proprietor, which is much broader than the concluding financial transaction. Smart cards are plastic cards that contain a computer chip. Smart cards store larger amounts of information than magnetic stripe cards. They can also update this information and secure it at a higher level than a magnetic stripe.
Elements of a typical Smart Card
Smart cards have the same three fundamental elements as all other computers: processing power, data storage and a means to input and output data. Processing power is supplied by a microprocessor chip (e.g. Intel 8051 and Motorola 6805), and data storage is supplied by a memory chip (EEPROM, FLASH, ROM, RAM). In some instances these elements can be combined in one chip. The means in which data is transferred varies from card to card. In order to operate, each card must have a power source, whether in a card reader or on the card itself. Below figure shows the main elements of microprocessor used in smart cards – CPU, ROM RAM and EEPROM
Microprsessor Chip Diagram Smart Card Configuration
Microprocessor
The microprocessor is the intelligent element of the smart card which manipulates and interprets data. The software utilized for manipulation and interpretation of the data is either embedded in memory during the manufacture of the card or input under the control of the microprocessor. Microprocessors in smart cards can be up to 16 bits with a 10MHz processor
Memory
The memory in a smart card can either be non-volatile, retaining data when power is switched off, or volatile, losing data when power is switched off. If the memory is volatile, the smart card would then require a battery to power itself. Memory can also allow data to be written to it and read from it, or only allow data to be read from it (read-only memory). In most cases smart card applications will require non-volatile memory to retain information such as the identity of the cardholder and the application software, and read/write memory to update stored information, such as a balance after a transaction is made.
Memory in smart cards can be categorized into three types: ROM, RAM and programmable read-only memory (PROM). ROM is non-volatile, and the contents are embedded in the chip during the manufacturing stage; once embedded, the contents cannot be altered. Currently, chips with up to 32Kb of ROM are available. RAM is volatile, and is used as a temporary storage space. Data can be written to it, altered, read and deleted from it. Currently, chips are available with more than 64Kb of RAM. There are two types of PROM: electrically programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM). EPROM cannot be reprogrammed. EEPROM can be reprogrammed, however its structure is more complex and susceptible to damage which makes it more expensive. Currently, chips with up to 8Kb of EEPROM are available.
Memory can be structured to provide different levels of security zones. The open zone holds non-confidential data, such as identity of the cardholder, but cannot be altered by an unauthorized person. The working zone holds confidential data that requires certain information to be given before access is allowed. For instance, a personal identification number (PIN) would be required before accessing the data for a purchase transaction and available credit. The secret zone holds completely confidential data, such as the PIN. The microprocessor can access this data to compare the PIN to the number input by the cardholder, which ensures the data never leaves the card.
Input / Output
There are several different ways to input and output data to and from the smart card. Contact cards usually contain a metallic contact on the surface which, when inserted in a slot in the read/write unit, links with a connector in the unit. Contactless cards use a contact less method of transmission and reception of data, which only require the card to be placed near or on the surface of the read/write unit. Super Smart Cards have an integrated keyboard and display unit, therefore not requiring a read/write unit. They may have contacts embedded in the surface of the card in order to transfer data to other electronic devices.
Power Source
Generally, there are three methods used to power smart cards:
From an external power source that feeds a current through contacts on the card
In this method, power is sent through two of the contacts when the card is inserted in the read/write unit. The card will then reset itself, and execute its program.
By transmitting power
In the second method, a type of contactless operation such as inductive coupling will transmit both power and data through the air or a non-metallic surface to the smart card, from the read/write unit.
By a battery embedded in the card
In the third method, a battery is incorporated in the card. This method is not popular due to the difficulty of meeting the ISO standards for dimensions, additional costs incurred from incorporating the battery in the card and problems associated with flexing a card containing a battery.
Types of Smart Cards
Depending on how the smart card is accessed, smart card can be classified into 4 main type:
Contact Smart Cards
These cards have a microelectronics embedded in the cards, with connections to metallic contact pads on the surface of the card (usually a small gold chip about 1/2" in diameter). The contacts page link with the read/write unit (Smart Card Reader) to enable the microcomputer to communicate and provide power to the microelectronics. There are a total of eight contacts: two are reserved for future allocation, two for supply voltage and ground, one for reset, one for the clock signal to provide timing for the microprocessor, and the remaining for input and output of data and power. The standard position for the contact is on the left of the card, on either the front or the back (ISO 7816-2). Many of the cards also incorporate a magnetic stripe to be compatible with existing equipment.
