Knowing a valid card number isn't all that hard if you're a good at math. Credit card machines use an extremely complicated mathematical algorithm to generate unique card numbers each time a transaction takes place. These are the main features of a legitimate card: It contains four groups of sixteen digits which are then divided into 4 groups of eight digits.
If the card contains five digits, the customer receives the card with the remaining digits written below the five-digit number on the card. A few card manufacturers make it possible for customers to input a five-digit number to have the remainder written below the remaining digits in the card. This method of generating a card has some benefits for the card processor. If a customer input the wrong card number and the card are returned to them, then they can have their money back.
The problem with this process is that it is very simple to forge a card by changing any of the digits in the card which could alter the way the card is used and therefore affect the validity of the card. It is also very easy for a card to be copied or lost because a fraudulent card could easily be copied and inserted into a card reader. There are no two identical cards, so a single duplicate can easily be created.
The solution to the issue of valid card numbers is a mathematical algorithm, which uses the fact that there are 16 digits to generate a unique card number from the remaining digits. Each of the remaining digits has a certain mathematical value associated with it. This mathematical value is known as a nonce. A nonce must be used in combination with each of the digits in order to generate a valid card.
Each card generated by the card processor has its own unique nonce that is required in order to determine whether the card number given by the customer is valid or not. The nonce serves as a basis for the mathematical algorithm that the card processor uses to determine the value of the nonce.
There are three separate algorithms that the card processor uses to determine the nonce for each card. In the first algorithm, all of the forces are multiplied together and the result is the number of digits that contain a certain mathematical value. After the third algorithm, the number of notes is divided by the total number of digits and then finally the remaining digits are summed.