Hello guys , we are back with another awesome article. In this series of articles ( credit card 101 ) we are going to learn about various credit cards , how credit cards work , how to hack credit cards and most important how to secure your personal credit card. So to start with credit card hacking we must first understand how credit cards are designed and how they work.
Table of Contents
Credit Card Numbers :
So lets consider a random credit card for example ( This is not my credit card ).
4485 3151 5882 2849
Now the credit card number is divided into various parts which help the payment gateway to charge the original consumer of the credit card.
1. The first number (4) is the MII
2. The next 5-6 numbers are the issuer ID
3. The next numbers leaving the last number are the user ID
4. The last number is the check number also known as check algorithm number.
What is MII ?
MII basically stands for major industry identifier . This is a constant number that is given to the consumer according to the needs of the consumer . For example in most cases a consumer uses his/ her credit card numbers for online transactions. This is the reasons most credit card numbers start from 4 and 5 which means banking and financial industry . This digit can range from 0 to 9. We will provide more information in the bottom of the article .
What is Issuer ID ?
The issuer ID basically stands for the card provider i.e. visa , mastercard , etc. For example if the digit is 4xxxx then it is a VISA card and the length of the card is 16. We have provided more information about in the bottom of the article.
What is User ID ?
This number is basically the Identity of the user and the bank to which the card was issued . It depends on the users account number and other details . This number can be reused if a particular card holder stops using the service.
What is check number ?
A check number is used to ensure the validity of the card. It is the last digit of the credit card. Credit cards follow luhn check algorithm.
Luhn’s Credit Card Algorithm :
Original Number : 4485 3151 5882 2849
1. From the back , double every alternate number.
What we get : 8 (16) 6 (10) (10) (16) 4 8
2. If the doubled numbers are double-digit numbers then add them.
What we get : 8 7 6 1 1 7 4 8
3. Write the alternate numbers that we deleted in the first step.
8475 6111 1872 4889
4. Add the new credit card number that we get.
5. If sum is a multiple of 10 then the credit card number is valid.
Since 80 is the multiple of 10 . We can conclude that 4485 3151 5882 2849 can be a valid credit card number.
MII/ Digit Value Category
0 = other industry assignments 1 = Airlines industry assignments. 2 = Airlines and other industry assignments 3 = Travel and entertainment 4 = Banking and financial 5 = Banking and financial 6 = Merchandising and Banking 7 = Petroleum 8 = Telecommunications and other industry assignments 9 = National assignment
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