Magnetic stripe card
From Wikipedia, the free encyclopedia
A magnetic stripe card is a type of card capable of storing data by modifying the magnetism of tiny iron-based magnetic particles on a band of magnetic material on the card. The magnetic stripe, sometimes called a magstripe, is read by physical contact and swiping past a reading head. Magnetic stripe cards are commonly used in credit cards, identity cards, transportation tickets, and so on.
A number of International Organization for Standardization standards, ISO 7810, ISO 7811, ISO 7812, ISO 7813, and ISO 4909, define the physical properties of the card, including size, flexibility, location of the magstripe, and magnetic characteristics. They also provide the standards for financial cards, including the allocation of card number ranges to different card issuing institutions.
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[edit] The magnetic stripe
The magnetic stripe was invented by IBM under a contract with the US government for a security system. Forrest Parry, an IBM Engineer, had the idea of securing a piece of magnetic tape, the predominant storage medium at the time, to a plastic card base. He became frustrated because every adhesive he tried produced unacceptable results. The tape strip either warped or its characteristics were affected by the adhesive making it technically unusable. After a frustrating day in the laboratory, trying to get the right adhesive, he came home with several pieces of magnetic tape and several plastic cards. As he walked in the door at home, his wife was ironing and watching TV. She immediately saw the frustration on his face and asked what was wrong. He explained the source of his frustration: inability to get the tape to "stick" to the plastic in a way that would work. She said, "Here, let me try the iron." She did and the problem was solved. The heat of the iron was just high enough to bond the tape to the card.
In most magnetic stripe cards, the magnetic stripe is contained in a plastic-like film. The magnetic stripe is located 0.223 inches (5.66 mm) from the edge of the card, and is 0.375 inches (9.52 mm) wide. The magnetic stripe contains three tracks, each 0.110 inches (2.79 mm) wide. Tracks one and three are typically recorded at 210 bits per inch (8.27 bits per mm), while track two typically has a recording density of 75 bits per inch (2.95 bits per mm). Each track can either contain 7-bit alphanumeric characters, or 5-bit numeric characters.
Magstripes following these specifications can typically be read by most point-of-sale hardware, which are simply generic general-purpose computers that can be programmed to perform specific tasks. Examples of cards adhering to these standards include ATM cards, bank cards (credit and debit cards including VISA and MasterCard), gift cards, loyalty cards, driver's licenses, telephone calling cards, membership cards, electronic benefit transfer cards (e.g. food stamps), and nearly any application in which value or secure information is not stored on the card itself.
Counterexamples of cards which intentionally ignore these standards include hotel keycards, most subway and bus cards, and some national prepaid calling cards (such as for the country of Cyprus) in which the balance is stored and maintained directly on the stripe and not retrieved from a remote database.
[edit] Magnetic stripe coercivity
Magstripes come in two main varieties: high-coercivity (HiC) at 4000 Oe and low-coercivity (LoC) at 300 Oe but it is not infrequent to have intermediate values at 2750 Oe. High-coercivity magstripes are harder to erase, and therefore are appropriate for cards that are frequently used or that need to have a long life. Low-coercivity magstripes require a lower amount of magnetic energy to record, and hence the card writers are much cheaper than machines which are capable of recording high-coercivity magstripes. A card reader can read either type of magstripe, and a high-coercivity card writer may write both high and low-coercivity cards (most have two settings, but writing a LoC card in HiC may sometimes work), while a low-coercivity card writer may write only low-coercivity cards.
In practical terms, usually low coercivity magnetic stripes are a light brown color, and high coercivity stripes are nearly black; exceptions include a proprietary silver-colored formulation on transparent American Express cards. High coercivity stripes are resistant to damage from most magnets likely to be owned by consumers. Low coercivity stripes are easily damaged by even a brief contact with a magnetic purse strap or fastener. Because of this, virtually all bank cards today are encoded on high coercivity stripes despite a slightly higher per-unit cost.
Magnetic stripe cards are used in very high volumes in the mass transit sector, replacing paper based tickets with either a directly applied magnetic slurry or hot foil stripe. Slurry applied stripes are generally less expensive to produce and are less resilient but are suitable for cards meant to be disposed after a few uses.
[edit] Financial cards
There are up to three tracks on magnetic cards used for financial transactions, known as tracks 1, 2, and 3. Track 3 is virtually unused by the major worldwide networks such as VISA, and usually isn't even physically present on the card by virtue of a narrower magnetic stripe. Point-of-sale card readers almost always read track 1, or track 2, and sometimes both, in case one track is unreadable. The minimum cardholder account information needed to complete a transaction is present on both tracks. Track 1 has a higher bit density (210 bits per inch vs. 75), is the only track that may contain alphabetic text, and hence is the only track that contains the cardholder's name.
The information on track one on financial cards is contained in several formats: A, which is reserved for proprietary use of the card issuer, B, which is described below, C-M, which are reserved for use by ANSI Subcommittee X3B10 and N-Z, which are available for use by individual card issuers:
Track one, Format B:
- Start sentinel — one character (generally '%')
- Format code="B" — one character (alpha only)
- Primary account number — up to 19 characters
- Field Separator — one character (generally '^')
- Name — two to 26 characters
- Field Separator — one character (generally '^')
- Expiration date — four characters
- Service code — three characters
- Discretionary data — may include Pin Verification Key Indicator (PVKI, 1 character), Pin Verification Value (PVV, 4 characters), Card Verification Value or Card Verification Code (CVV or CVK, 3 characters)
- End sentinel — one character (generally '?')
- Longitudinal redundancy check (LRC) — one character
LRC is a form of computed check character.
The format for track two was developed by the banking industry (ABA). This track is written with a 5-bit scheme (4 data bits + 1 parity), which allows for sixteen possible characters, which are the numbers 0-9, plus the six characters : ; < = > ? . The selection of six punctuation symbols may seem odd, but in fact the sixteen codes simply map to the ASCII range 0x30 through 0x3f, which defines ten digit characters plus those six symbols. The data format is as follows:
- Start sentinel — one character (generally ';')
- Primary account number — up to 19 chars
- Separator — one char (generally '=')
- Expiration date — four characters
- Service code — three characters
- Discretionary data — as in track one
- End sentinel — one character (generally '?')
- LRC — one character
[edit] Driver's Licenses (USA)
The data stored on magnetic stripes on American driver's licenses is specified by the American Association of Motor Vehicle Administrators (AAMVA).
The following data is stored on track 1:
- Start Sentinel - one character (generally '%')
- State or Province - two characters
- City - unknown length
- Field Separator - one character (generally '^')
- Last Name - unknown length
- Field Separator - one character (generally '$')
- First Name - unknown length
- Field Separator - one character (generally '$')
- Middle Name - unknown length
- Field Separator - one character (generally '^')
- Address - unknown length
- Field Separator - one character (generally '^')
- Unknown (spaces on mine) - unknown length
- End Sentinel - one character (generally '?')
The following data is stored on track 2:
- ISO Issuer Identifier Number (IIN)
- Drivers License / Identification Number
- Field Separator — generally '='
- Expiration Date
- Birth date
- DL/ID# overflow
The following data is stored on track 3:
- Template V#
- Security V#
- Postal Code
- Class
- Restrictions
- Endorsements
- Sex
- Height
- Weight
- Hair Color
- Eye Color
- ID#
- Reserved Space
- Error Correction
- Security
[edit] Other card types
Smart cards are a newer generation of card containing an integrated circuit chip. The card may have metal contacts connecting the card physically to the reader, while contactless cards use a magnetic field or radio frequency (RFID) for proximity reading.
'Hybrid' smart cards include a magnetic stripe in addition to the chip — this is most commonly found in a payment card, so that the cards are also compatible with payment terminals that do not include a smart card reader.
[edit] External links
- Magnetic Stripe Formats
- Magnetic Stripe Card Standards (from DED Ltd)
