The Friday Fillip
I had occasion to cancel a credit card and get a new one recently, which made me look at and think about credit card numbers. I suppose that I’d always thought of them as a more or less random string of integers, maximizing the number of such strings that would be available to banks etc. (10 X 10 X 10 etc. for each integer place…) and making it just that bit more difficult for criminals to suss out a number.
Turns out I couldn’t be more wrong: credit card (and bank card) numbers are highly structured entities and only make . . . [more]


