Smart cards are small credit card shaped devices which contain a microprocessor and embedded memory. Due to it's size and processing power it can be used in a number of applications - everything from phone cards to individual identifiation cards.
For identity related applications (library cards, customer cards, etc) where only one card is issued to a particular user, the smart card holds the individual's data within different files on the card in a system similar to that of a Linux directory structure.
Because smart cards have microprocessors embedded into them they require a source of power to function as well as some form of mechanism in order to send and receive data. Smards do this in different ways depending on whether they are Contact or Contactless smart cards. Contact based smart cards have gold plated contact pads in one corner of the card and are used to supply the required energy and to communicate with the card reader. When the contact card is inserted into the reader, the contacts in the reader sit against the pads on the card and data can be tranmitted via the various pin connections.
Readers for contact card are generally a separate unit which is plugged into a USB or serial port. Some keyboards, PCs and PDAs have built in card readers similar to those found in GSM mobile phones. Some also have embedded readers for GSM mini smart card readers.
Predictably, contactless smart cards don't have a contact pad on their surface. Any communication is done via radio frequency (RF). These cards have a small wire loop embedded inside which is used as an inductor to supply energy to the card and to transmit data. When the contactless card is inserted into the card reader's RF field, a current is induced which can then be used as the energy source. As the RF field is modulated, the current in the inductor changes and communication takes place.
Smart card readers are usually connected to a PC via a USB or serial port. Because contactless cards don't require insertion into a reader, their card readers usually consist of a serial interface to the computer and an antenna to connect to the card. Some of these card readers may or may not have a slot, the reason being that some cards can be read from up to 1.5m away however some need to be positioned a few millimetres away from the reader in order for accurate communication to take place.
Another type of smart card is the combo card, which has a contact pad which can be used specifically for transmission of large amounts of data such as PKI credentials. It also contains a wire loop like the contactless card's so that it can be authenticated. Contact based smart cards are primarily used for electronic security whereas contactless smart cards tend to be used in areas such as transportation or door locks.
It is easy to see why smart cards are so widely used. They are much more cost effective than their swipe card equivalents and are significantly more cost effective.
Dave Matthews is writing on behalf of Universal Smart Cards, a leading online Smart Card retailer.
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