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How Credit Card Numbers Are Coded

Thursday, January 27, 2011 - 7:28 AM
Interesting infographic from the blog shows how those 16-digit credit card numbers are coded.
Ken TuminKen Tumin5,471 posts since
Nov 29, 2009
Rep Points: 125,634
1. Thursday, January 27, 2011 - 10:34 AM
The parity-check calculation is a challenging homework assignment; it took me three times to get it right:D

While it is interesting technically, I am unclear about the purpose of releasing such information to the general public ... more information to thiefs and crooks (nicely coined as "code breakers")!

Thanks a lot, Mint!
51hh51hh1,476 posts since
Jan 16, 2010
Rep Points: 6,427
2. Thursday, January 27, 2011 - 10:49 AM
It's not quite giving away the farm, although it is additional information for thiefs and crooks - who unfortunately are probably already well-versed in this type of information. 

Beyond the card number, one would also need a correct valid-through date (although admittedly this has only a finite number of possibilities) and possibly a CVC as well.  Additionally, when shopping online, some retailers also validate the customer's name to the name on the card. 

That said, I would have preferred that the validating algorithm had not been published, as it is not clear what useful purpose it served to do so.
pearlbrownpearlbrown1,472 posts since
Nov 2, 2010
Rep Points: 6,396
3. Saturday, January 29, 2011 - 2:01 PM
This is hardly the first time it's been published online.
dewandewan4 posts since
Jan 23, 2011
Rep Points: 21
4. Saturday, January 29, 2011 - 3:07 PM
  This is hardly the first time it's been published online.

Of course not.  But the point is why braodcasting it on internet.  It is one more piece of the puzzle being compromised.  This will make the credit card code-breaking just one-step easier. 

Just like SSL or RSA encryption, one can always search for some decryption algorithms online.  But there is no need going around broadcasting the information from house to house.

51hh51hh1,476 posts since
Jan 16, 2010
Rep Points: 6,427