Card Access Control

Magnetic stripe technology uses a stripe of magnetic oxide tape laminated on a keycard card. Three tracks of data, which can be encoded in any format, are on the magnetic stripe. Mag-stripe cards, as they are called, are inexpensive and easy to program and use. On the down side, the technology is susceptible to misreads, card wear, data corruption, and copying.

Barcode technology uses a series of alternating dark and light stripes that are read by an optical scanner. The organization and width of the lines is determined by the bar code protocol chosen.

Bar codes are inexpensive and easy to generate, but this also makes them susceptible to fraud, and smudges and dirt may cause problems with the reader.

Smart cards come in two types: contact and contactless. Both have an embedded microprocessor and memory that can handle multiple application and allow the smart card to work as a cash card, a pre-paid membership card, and an access control card.

The difference between contact and contactless smart cards is how their microprocessors communicate. A contact smart card has eight contacts that must physically touch the right points on the card reader, which makes them slow and undesirable for most access control purposes, which require speed of transaction.

A contactless smart card uses the same radio-based technology as the proximity card but with a higher frequency that allows for transfer of more data and communication with several cards at a time. Contactless cards do not have to touch the reader and remain in a wallet or purse, which makes them a better choice for access control systems. The cards usually do not use the available memory for access control, which frees the memory for uses like biometrics data.

Many companies use proximity cards to control physical access. In this system, an employee holds a card within a few inches of the reader; the reader receives a unique ID from the card and transmits it to a central computer that commands whether or not to open the door. A primary reason for the popularity of proximity cards is the convenience of their touch-less functionality.

One drawback to proximity cards is the increasing number of cards manufactured with no governing body to control card numbers and facility codes, key parts of their operating format. Different manufacturers could supply cards with identical facility codes and control numbers to different organizations, which causes a problem of duplicates.