Magnetic strip cards and readers

Author: Chris Connolly

Definition

A magnetic strip card is usually a magnetized strip card used for payment processing on which data can be sent and received.


Description

Such strip cards are usually made of small particles of iron (or another metal) for which the end user can perform read/write tasks such as payment processing in Supermarkets and Banks to passport control in airports. The data is stored by changing the magnetism of the particles contained within the strip card. Today such cards are widely used for:

  • Banking (debit or credit cards) and other functional places where POS systems are used
  • Tickets issued for transportation or in parking lots.
  • Keys in hotels and other buildings
  • Access systems - i.e getting into work carparks
  • Systems to track working hours in companies
  • Loyalty cards/Gift cards



Explanation and application


When you swipe the magnetic strip card, how does it read it?

The magnetic strip can be "written" to because the tiny bar magnets can be magnetized in either a north or south pole direction.
Instead of motors moving the tape so it can be read, your hand provides the kinetic motion as you "swipe" your card through a reader or insert it in a reader at the gas station pump etc.

Types of data available to store on a strip card:

There are three tracks on the magnetic strip card. Each track is about one-tenth of an inch wide. The ISO/IEC standard 7811, which is used by banks, specifies:

  • Track one is 210 bits per inch (bpi), and holds 79 6-bit plus parity bit read-only characters.
  • Track two is 75 bpi, and holds 40 4-bit plus parity bit characters.
  • Track three is 210 bpi, and holds 107 4-bit plus parity bit characters

Your credit card typically uses only tracks one and two. Track three is a read/write track (which includes an encrypted PIN, country code, currency units and amount authorized). Track three is only used on credit cards and passports - effectively those cards which need advanced security and encryption. Loyalty cards are being released with PIN numbers associated with the cards nowadays also which would use this third track.


The information on track one is contained in two formats: A, which is reserved for proprietary use of the card issuer, and B, which includes the following:

  • Start sentinel - one character
  • Format code="B" - one character (alpha only)
  • Primary account number - up to 19 characters
  • Separator - one character
  • Country code - three characters
  • Name - two to 26 characters
  • Separator - one character
  • Expiration date or separator - four characters or one character
  • Discretionary data - enough characters to fill out maximum record length (79 characters total)
  • End sentinel - one character
  • Longitudinal redundancy check (LRC) - one character LRC is a form of computed check character.


The format for track two, developed by the banking industry, is as follows:
  • Start sentinel - one character
  • Primary account number - up to 19 characters
  • Separator - one character
  • Country code - three characters
  • Expiration date or separator - four characters or one character
  • Discretionary data - enough characters to fill out maximum record length (40 characters total)
  • LRC - one character


Advantages of Magnetic Stripe cards:

Simple for people to use - little or no training required
Cards are inexpensive to produce
Data on the cards can be altered if necessary
Security is improved by the use of PIN numbers to confirm that the person is the rightful card owner

Disadvantages of Magnetic Stripe Readers:

Very limited storage capacity for data
Data can be easily destroyed by strong magnetic fields
Not always secure as thieves can obtain the readers and read the data on the card.


Images of standard readers and cards


external image aW0UVb1c4e0JuGFpxIXoM9EM9fJSofpWNHBqpMTU8mGydH9DCZp18Uk1IV9wN__Cjz36VA3d4w7hunGXdRauXGboxXv-ea0fbXFaKbm_cAuA34_yXHsTWYalBT6ARbpDcAexternal image GAOV4bYyFujldW-ZsJwDOgbfQii4WpsaAPXqwhZJ00WxYABmvn10aV2gGbfHE-X4xx_o9qveWkunSHK_MHGQnuSQ5yGXIJnc7Ca3nZBgi9EO7wOerwlLHMI2vyOqjPAgkgexternal image THCg7mjx26TF5Lxjuz_s5PH-YhiVBoj3Jt657xkgoWsskrBL1KkvebWNgmIS9-Qnl8oJ_oDnMhIuQvVMZUXoBVA-2kmQrHvlLdYaWpwqNxn4wQMzDmuaQKuKak-T8YI7GA





References and resources


http://simple.wikipedia.org/wiki/Magnetic_stripe_card
http://money.howstuffworks.com/personal-finance/debt-management/credit-card2.htm
https://nz.answers.yahoo.com/question/index?qid=1006012504961
http://money.howstuffworks.com/personal-finance/debt-management/magnetic-stripe-credit-card.htm