Engineering credit card without software

Posted: November 19, 2011 in Uncategorized

Of the 16 numbers you see in the Visa or MasterCard credit card, the first 6 digits is the”issuer identifier”, ie the credit card type code. If the sixth digit is preceded by 4, meaning the credit card type is Visa. However, if the six digits are preceded by 5, meaning the creditcard type is MasterCard. Next, a last digit of 16 digit numbers on the credit card serves as a”check digit”, whose function is only for the validation checks credit card numbers. Since the initial 6 digits and last digit 1 is already a significance, meaning remaining 9 digits in the middle that serves as an “account number”. Therefore there were 10 possible numbers(from the digits 0 to 9) which can be inserted into each digit from 9 digit “account number” is, then the resulting combination of 9 digits amounted to 1 billion possible numbers foreach type of credit card (visa or MasterCard). The algorithm used to generate a row of 16 points for credit card numbers is called an algorithm “Luhn” or “Mod 10”. Back in 1954,Hans Luhn of IBM is the person who first proposed the application of algorithms to determine the validity of a credit card number. The workings of a simple algorithm (butexcellent) are as follows:
1.   Starting at the first digit, multiply two-digit occupies all odd numbers, so as a whole will have 8 digits that you multiply by 2, the digit to 1, 3, 5, 7, 9, 11, 13, and 15.
 2.  If the square 2 result in a number of two digits (10, 12, 14, 16, or 18), the sum of each digit numbers to produce a new digit, so that the results of the first and second steps are fixed in the form 8 the number.
3.   The next step, replace all the numbers (credit card number) located in the odd positiondigits with 8 new figures, to generate a new row of 16 points.
4.   The final step, add up to-16 figure.If the sum is a multiple of 10, meaning the credit card number is valid, and conversely, if nota multiple of 10, meaning the credit card number is invalid. Below I give examples of actualcalculations:
As you can see in the picture above this, the credit card number is 4552 7204 1234 5678,because it begins with 4, it means the card type Visa. Now we do the calculations.
If you have carefully calculated, it will be seen that the final count is 61, which is NOT amultiple of 10 numbers, so that we can be sure that the credit card number is invalid. If the “check digit” in the example is not 8, but 7, then the algorithm, the credit card number will bevalid, because the total sum will be changed to 60, a number is a multiple of 10. Here’s another example:
Once again, do the calculations according to Luhn algorithm above for MasterCard creditcard number is 5490 1234 5678 9123.
As you can count itself, the total sum is 65, so the credit card number is invalid, because thenumber 65 is NOT a multiple of 10.
If only, “check digit” credit cards instead of 3, but 8, then sum the results would be 70, which is a multiple of 10, so that the credit card number will be valid (the algorithm). Validunderstanding of the above is valid mathematical calculation, it does not mean that creditcard number is absolutely certain that the original credit card number.
Due to credit card checks (at the time of online transactions, for example) is required notonly a credit card number only, but also “expiry date”, and “card security code” or collectively, the CVV (Card Verification Value) or CVC (Card Verification code) which is the last 3 digits behind the credit card.
PS: For American Express credit card, the number of digits instead of 16, but only 15, andalways begin with 34 or 37 for the first 2 digits.As for the “account number” it only has a length of 8 digits, not 9 digits such as credit cardtype Visa or MasterCard.
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