In the algorithm Credit Card
In the real world, of course you already know, or at least heard how credit card has been widely accepted in the community. Various shops, and service providers have been receiving payments by using the card credit. Currently in the virtual world (the Internet), payment by credit card also has started widely accepted. Various crimes have been frequently conducted with use this credit card, both in the real world and in the virtual world. However, in this article I will not discuss about the security of credit card, I just discuss a small thing called checks digits on a credit card. This is indeed quite small, but it should be by all people. In the process of payment on the Internet using a credit card, there is a The very process of authentication is required, this is a process for prove that the credit card number is entered correctly, and that is the person who has the right to use the card. This seems easy, a program can be directly connected to the server bank and can be examined directly, but this is certainly enough time, What if the card number was entered wrong type, all connections to the bank server, all search data, and others will be futile. For (slightly) to solve the above problem, credit card numbers have been designed
in such a way so that the possibility of the initial checks before a number were checked through the bank. These checks are checks combination of digits that are commonly known as algorithms check digit. Check digit algorithms used in the credit card is the check digit Luhn algorithm (Luhn check digit algorithm).
Check Digit Luhn algorithm Check digit algorithm is an algorithm used to check the validity of a digit number based on the Creative-digits. Either application is very common that we find in daily life is a process importation of goods data that we purchase in the supermarket to buy a small (the still use manual input, do not use the bar code reader). Maybe sometimes you see the cashier sometimes incorrectly entered data so that little error message appears, and then he re-type the code again
the goods listed in the goods. Have you thought how a computer can know that the numbers are incorrect. The answer is by using a check digits, usually the last digit of the code of goods is the result of mathematical operations to the digit-digits before, so if there is direct input error
detected, for example, the code is 98876768532 goods, but that is inserted 98876768533
the computer will consider this data is incorrect. You check digits This does not exist, and each code sequence made goods, computers will be considered correct all data is entered, you may buy a listed Silver Queen chocolate when you buy a brand of chocolate is another.
To check digit Luhn algorithm, I actually understand the history of less check digits with this algorithm, but the algorithm is used by all the big banks issued credit card (Visa, MasterCard, Amex, Novus, and may still many others). Check digit algorithm is also used in ATM cards, at least I have noticed an ATM card and BNI bank likely BII bank others also use this method. When introducing the Telkom TeCC (Telkom Calling Card), these algorithms are also used.
Method check digit is actually simple, need only three steps to to prove whether a card check digit meet the Luhn algorithm, for cards even with the number of digits (eg Visa [16 digits], MasterCard [16 digits], and Novus [16 digit]) do the following:
1. for each digit in the odd position (I count the digits from the start left with the most digits to the left-1), multiply the value by two, if the results more than 9, subtract the result by 9. Total number of all that it has obtained.
2. digits for each position on the whole, and the total value of all add the results with the results of the first steps.
3. if the results on the second step is divided out of 10, means the card number legitimate. Not easy, for cards with the odd number of digits (for example, Visa [13 digits], Amex [15 digits]) how to do the same, only the first step is multiplied digits even in the position, and the steps that are both is the digits in the odd position.
Example:
If I have a card with the numbers:
7889-8594-5435-5413
and I want to know whether this really a valid credit card number or I can not perform the following steps (note the number of digits are 16):
1) multiplying all the numbers on the two-digit odd and reduce 9 with the result if more than 9, and are This is the digit-digits in the odd position
D01 = 7
D03 = 8
D05 = 8
D07 = 9
D09 = 5
D11 = 3
D13 = 5
D15 = 1
If the operation is done two times and reduce 9 (if more than 9) obtained
D01 = 7 x 2 = 14, because it is less the result of the 9 D02 = 14 - 9 = 5
D03 = 8 x 2 = 16, because it is less the result of the 9 D02 = 16 - 9 = 7
D05 = 8 x 2 = 16, because it is less the result of the 9 D02 = 16 - 9 = 7
D07 = 9 x 2 = 18, because it is less the result of the 9 D02 = 18 - 9 = 9
D09 = 5 x 2 = 10, because it is less the result of the 9 D02 = 10 - 9 = 1
D11 = 3 x 2 = 6, less so from 9 remain 6
D13 = 5 x 2 = 10, because it is less the result of the 9 D02 = 10 - 9 = 1
D15 = 1 x 2 = 2, less so from 9 fixed 2
The number of D01, D03 + + D05, D07 + + D09, D11 + + D13, D15 + = 5 + 7 + 7 + 9 + 1 + 6 + 1 + 2 = 38
2) adding all the digits in the position even
D02 = 8
D04 = 9
D06 = 5
D08 = 4
D10 = 4
D12 = 5
D14 = 4
D16 = 3
Amount = 8 + 9 + 5 + 4 + 4 + 5 + 4 + 3 = 42
When the results of step 1 and step 2 are obtained 38 + 42 = 80, because 80 out of 10 then divided the number of valid credit card number. It is clear now, check out algorithms digits on a credit card is very easy You can also do produce numbers as a valid card number credit using the program, and he said it could be used for to make credit card fraud is still my own little way with because according to my current inspection is far more strict and almost someone might not pass with only Seeing the number of valid only without expiration date and name of the owner.
source : fineprint.com
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