Adding credit card regexes

[daedalus]

No description provided.

[coffeetocode]

These FPd a lot in my testing.

Suggest adding lookahead and lookbehind assertions to to cut down on other types of number strings getting included (eg, 16 digits that look like a MOP in the middle of a string of 20 digits):

    "Generic MOP": "(?<=[^\\da-zA-Z.]|\\s)[3456][0-9]{14,15}(?=[^\\da-zA-Z]|\\s)",
    "Visa": "(?<=[^\\da-zA-Z.]|\\s)4[0-9]{12}(?:[0-9]{3})?(?=[^\\da-zA-Z]|\\s)",
    "MasterCard": "(?<=[^\\da-zA-Z.]|\\s)(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}(?=[^\\da-zA-Z]|\\s)",
    "American Express": "(?<=[^\\da-zA-Z.]|\\s)3[47][0-9]{13}(?=[^\\da-zA-Z]|\\s)",
    "Diners Club": "(?<=[^\\da-zA-Z.]|\\s)3(?:0[0-5]|[68][0-9])[0-9]{11}(?=[^\\da-zA-Z]|\\s)",
    "Discover": "(?<=[^\\da-zA-Z.]|\\s)6(?:011|5[0-9]{2})[0-9]{12}(?=[^\\da-zA-Z]|\\s)",
    "JCB": "(?<=[^\\da-zA-Z.]|\\s)(?:2131|1800|35\\d{3})\\d{11}(?=[^\\da-zA-Z]|\\s)"

[dxa4481]

Even with the lookaheads and lookbehinds I'm still getting a lot of false positives. I ran it on the Square org, which I figured would be a good candidate for CC numbers, and it fires on a lot of crypto libraries, and other unrelated things.

[pizen]

Valid credit card numbers are going to be hard to identify using only a regex. I think you'd need to add some post-match processing to validate the checksum (https://en.wikipedia.org/wiki/Luhn_algorithm).