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In general, a card with a magnetic stripe is a dinosaur that should have died a long time ago. The era of cryptoassets has been around for a long time
But thanks to the most backward market, such cards still exist. By the way, what do you think is the most backward market in terms of card technology? Do not believe it ... USA! No kidding. And the most developed? .. Not so difficult to guess. Asiatic! And the Russian one is somewhere closer to the front line. We are a little behind Asian, but in general - quite on the level.
With the USA, everything is simple. Since the homeland of the cards is the United States, there is most of the equipment for receiving there. And it still works, why just change it? In addition, the main payment systems are from there, and therefore protect the interests of US banks and do not force (although they are pushing) to replace equipment.
In general, the contents of the magnetic stripe are of more academic interest. We will satisfy him today.
Although, by the way, microprocessor cards use a block of information, which is arranged in the same way as information on a magnetic stripe. Well, then I'll tell you sometime later.
There are three tracks on the magnetic stripe, or three tracks. Only the first two are standardized. There are no general standards for the third track (although there are industry or private standards). The first two tracks are read-only (although technically they can be rewritten). And the third was intended for both reading and writing. But he did not go to the people. Somehow I'll tell you about his difficult fate
When the cards were developed, two unrelated but similar problems were solved. One task is for the automatic check-in of passengers in airlines, the second task is the automation of payment. Since he was developing equipment for both IBM tasks, he decided to combine the solutions. Tracks 1 and 2 differ in recording density (track 1 holds more). Their content is very similar, although slightly different.
Service symbols can actually be different, there are several options. After the starting symbols comes the card number - it must be exactly the same as the one that is written on the card itself. This number is called PAN - Primary Account Number, the number of the main account. But in practice, it never coincides with the bank account number (due to legal requirements for the account number, for example). It actually consists of a Bank Identification Number, an account number, and a check digit.
The bank receives the BIN from the payment system when it enters it. Each payment system has its own initial digits, therefore, looking at the card number, you can understand which payment system it belongs to.
PAN is followed by the name and surname of the holder (by the way, this particular data is not on the second track, this is the main difference). Then there are three important pieces of data.
The card is valid for four digits. The first two - a year, the second - a month.
Further - the so-called. a three-digit Service Code. The first number means the type of card. If it is 1 or 5, then the card has a magnetic stripe. If it is 2 or 6, then a card with a chip. Values 5 and 6 mean that the card is for operations only within the country, and 1 and 2 - that it can be used in other countries too.
The second number speaks about the rules for checking the card. For example, 0 - PIN need not be checked, 2 - PIN is always checked.
The last figure is about the rules for servicing the card. You can, for example, prohibit withdrawing cash (only payment in terminals), etc.
The next important block is Discretionary Data. Card verification data. In general, there is no single standard here; each card publisher can use this block in his own way. But typically there are values like CVV (Card Verification Value) and PVV (PIN Verification Value) along with the PVKI required for it.
We will not delve deeply, I will explain in simple words what kind of data it is and why it is.
They are needed in order to check the correctness of the reported data. The CVV and PVV values are calculated using secret keys that only the issuing bank knows. Both values are designed in such a way that it is impossible to get the initial data from them. To check the correctness, the bank repeats the same actions with the entered data and receives the calculated values of PVV and CVV, and compares them with those that are stored in its database. If they match, then the initial data can be trusted.
At the end of the track there is an LRC (Longitude Redundancy Check) symbol - a special value that is calculated over all other symbols on the track. He solves a purely technical problem - if the track was considered an error, then the LRC will not match. LRC is a pretty simple value, no encryption, nothing. Just integrity control. Similar algorithms for data integrity control are used in almost all communication channels.
And the last thing, why the data on the tracks is different.
If you have damaged track 1, but track 2 is being read successfully, in the overwhelming majority of cases you will not even notice anything, because the second track is the main one for bank cards. The only exception is if the card is a credit card and you are performing a lending operation. Then you won't go anywhere without the first track. And this is due to the fact that a loan agreement (or a special check) must be printed, in which the name and surname of the holder must be indicated. And you can take them only from the first track.
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