2. The meaning of the numerical arrangement of the credit card number. We take the Bank of China Great Wall Global Pass VISA chip credit card as an example to analyze the numerical meaning of the credit card. The card number is a 16-digit number, in groups of four, and a * **Four groups. So what does this arrangement mean? Let’s take a look at the table below: In this table, we can clearly see that the 1-6 digits of the card number in the bright yellow area are the card issuing bank identification code, which is the BIN code we are familiar with; the card number 7 in the khaki area -The 15-digit number is a bank account (except for American Express cards, the same below). Its meaning is customized by the card issuer. Each bank has different definition standards, so we will not go into detail one by one; while the grass green area is 16th The digit is a check digit, or check digit in English. It is used to verify the validity of the card number. I will talk about how this number is calculated later.
3. Card Issuing Bank Identification Code (BIN Code) Let’s first understand what is the Card Issuing Bank Identification Code (BIN Code). Many card friends know that this is a 6-digit number assigned to the bank by the card organization, but many people may not know exactly where it comes from. The first six digits of the card number are called BIN, which is the abbreviation of the English Bank Identification Number; this group of numbers is also called IIN, which is the abbreviation of the English Issuer Identification Number (Issuer Identification Number), which is formulated in accordance with the ISO/IEC7812 document . These numbers help cardholders and merchants identify the card's issuer. Bank card numbers that comply with the ISO/IEC7812 standard are usually 16 digits and can be up to 19 digits long. The standard structure is as shown in Table 1. According to the ISO/IEC7812 specification, strictly speaking, the first digit of the card number is MII--Major Industry Identifier, which is the main industry identification code, which can easily help us identify the industry to which the card belongs. For example, numbers starting with 3 are allocated to the tourism, entertainment and banking/financial industries, numbers starting with 4 and 5 are fully allocated to the banking/financial industry, and numbers starting with 6 are allocated to commerce and banking/financial industries. The 2-6 digits of the card number are called IIN, which is the issuer identification number. Of course, we are discussing bank cards here, so there is no need to go into detail. Interested friends can search for information online by themselves. For the sake of simplicity, we still use the BIN code to refer to the first 6 digits of the bank card. The IIN database and members are managed by the American National Standards Institute (ANSI) and updated monthly. The American National Standards Institute is responsible for assigning IIN ranges to issuing networks. UnionPay applies to this organization for an international standard card number starting with 62. There are many websites that provide BIN code query. We only need to enter the first 6 digits of the card to know the issuing country and bank of our card, as well as the card type. Here is a website for BIN code query. Friends who are interested may wish to query it themselves. Card types, of course the results are for reference only.
4. The 7th to 15th digits of the card number and the 7th to 15th digits of the credit card are the bank account. They are all defined by the bank itself. The rules of each bank are different. As long as everyone understands it as This is your own bank account. Let me talk about the Bank of China Great Wall Global Pass Card. The set of account numbers of Great Wall Card is very interesting. He defines the 7-8 digits of the card number as the identification number of the provincial card issuing bank, such as 31 representing Shanghai, 32 representing Jiangsu, etc. The remaining 9-15 digits are your account number, and the last digit is still the verification code.
Let’s look at Table 2 below to understand the card number structure with the characteristics of the Bank of China Great Wall Card: By the way, we will provide you with the provincial issuing bank identification numbers of the Great Wall Global Card: Beijing 11, Tianjin 12, Hebei 13, Shanxi 14, Inner Mongolia Autonomous Region 15, Liaoning 21, Jilin 22, Heilongjiang 23, Shanghai 31, Jiangsu 32, Zhejiang 33, Anhui 34, Fujian 35, Jiangxi 36, Shandong 37, Henan 41, Hubei 42, Hunan 43, Guangdong 44, Shenzhen 48, Guangxi 45, Hainan 46 , Chongqing 50, Sichuan 51, Guizhou 52, Yunnan 53, Tibet 54, Shaanxi 61, Gansu 52, Qinghai 53, Ningxia 64, Xinjiang 65. Interested friends may wish to check the Great Wall Card in their hands.
5. The last digit of the check code is now the last check digit of the card. But before introducing the sixteenth digit of the check code, we first learn a proper noun. -------Luhn algorithm. The Luhn algorithm, also known as the "Modulus 10 or Mod 10" algorithm, is a simple checksum algorithm, generally used to verify identity codes, such as card issuer identification codes, international mobile phone numbers, etc. Equipment Identifier (IMEI), U.S. National Provider Identification Number, or Canadian Social Security Number. It was created by IBM scientist Hans Peter Luhn. He applied for a patent on January 6, 1954, and was issued a patent on August 23, 1960. U.S. Patent No. 2950048. This algorithm has been widely used. For example, the ISO/IEC 7812-1 standard related to our credit card adopts this algorithm. It is designed only to prevent accidental errors rather than malicious attacks. Many credit cards and numerous government identification numbers use this algorithm to extract valid digits from a series of random numbers, but China UnionPay does not use this algorithm, and it is unknown what algorithm is used. Let’s use the real card number in this article to understand the characteristics of this algorithm and see how to calculate the last check digit, which is check code 9. Calculation steps: 1. The third column, starting from the check digit, going from right to Left, multiply the even digits by 2, and then add the ones and tens digits of the two numbers; 2. In the fourth column, add the obtained number and the odd digits of the original number string together to get 71; 3. Get the result The single digit of 1 4. Subtract the single digit 1 from 10 to get 9, which is the last digit of the check code in the real card. Another algorithm is to follow the above steps 1-2 to calculate the total of 71, and then: 1. The result is 71 multiplied by 9 to get 639. 2. Take the single digit of the result, 9, which is the check code. Now we know that the last digit of the credit card check code is calculated through the Luhn algorithm, and its function is to verify the card. Validity, rather than a random number printed on the bank computer. Some popular online credit card number generators also use this algorithm to generate credit card numbers. Although such card numbers are valid, they are still fake cards and cannot be used for real online transactions.