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How Do Magnetic Cards Work
| Cardjett: Our Hospitality Access Cards contain a magnetic stripe at the back of the plastic cards. The plastic cards are widely use by hotel industries. |
Data is laid out on a standard magnetic card in three tracks. A magnetic stripe card may have any of these tracks, or a combination of these tracks.
Track 1 was the first track standardized. It was developed by the International Air Transportation Association (IATA) and is still reserved for their use. It is 210bpi with room for 79 7-bit characters.
Track 1 is encoded with a 7-bit scheme (6 data bits plus one parity bit) that's based on ASCII. If your reader does not perform the ASCII conversion, all you have to do is add 0x20 to each byte to turn it into ASCII (there are no "control" characters). The seventh bit is an odd parity bit at the end of each byte. Click here for details on Track 1 data schema.
Track 2 was developed by the American Bankers Association (ABA) for on-line financial transactions. It is 75bpi with room for 40 5-bit numeric characters.
Track 2 is encoded with a 5-bit scheme (4 data bits plus one parity bit.) To convert this data into ASCII, add 0x30 to each byte. Click here for details on Track 2 data schema.
Track 3 is also used for financial transactions. The difference is its read/write ability. It is 210bpi with room for 107 numeric digits. Track 3 is used to store the enciphered PIN, country code, currency units, amount authorized, subsidiary account information, and other account restrictions.
Track 3 has the same properties as track 1 (start and end sentinels and an LRC byte), except that there is no standard for the data content or format. Track 3 is not currently used by any national bank card issuer.
In those rare systems where the PIN is stored on the card, this is the track where it is stored.
Track 1 Fields
| Start sentinel |
1 byte (the % character) |
| Format code |
1 byte alpha (The standard for financial institutions specifies format code is "B") |
| Primary Account number |
Up to 19 characters. American Express inserts space characters in
here in the same places the digits are broken up on the face of your
card. |
| Separator |
1 byte (the ^ character) |
| Country code |
3 bytes, if used. (The United States is 840) This is only used if the account number begins with "59." |
| Surname |
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| Surname separator |
(the / character) |
| First name or initial |
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| Space |
(when followed by more data) |
| Middle name or initial |
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| Period |
(when followed by a title) |
| Title |
(when used) |
| Separator |
1 byte (^) |
| Expiration date or separator |
4 bytes (YYMM) or the one byte separator if a non-expiring card. |
| Discretionary data |
Optional data can be encoded here by the issuer. |
| End Sentinel |
1 byte (the ? character) |
| Longitudinal Redundancy Check (LRC) |
1 byte. The LRC is made up of parity bits for each "row" of bytes,
making the total even. That means that the total of all the bit 1s of
each byte has to come out to an even number. Same for bit 2, etc. The
LRC's parity bit is not the sum of the parity bits of the message, but
only the parity bit for the LRC character itself. (It's odd, just like
any other single byte's parity bit.) |
Mag Track 2 Data Schema
Track 2 Fields
| Start sentinel |
1 byte (0x0B, or a ; in ASCII) |
| Primary Account Number |
Up to 19 bytes |
| Separator |
1 byte (0x0D, or an = in ASCII) |
| Country code |
3 bytes, if used. (The United States is 840) This is only used if the account number begins with "59." |
| Expiration date or separator |
4 bytes (YYMM) or the one byte separator if a non-expiring card |
| Discretionary data |
Optional data can be encoded here by the issuer. |
| End Sentinel |
1 byte (0x0F, or a ? in ASCII) |
| Longitudinal Redundancy Check (LRC) |
1 byte. |
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