Credit Card Number Generator

I got bored one night and decided to create this as a quick exercise. This is a number generator that satisfies the luhn + MOD 10 algorithm that is used by credit card numbers.

Different issuers/banks will use different prefixes. For instance, Visa will use values 40-49 while MasterCard uses 50-59. A complete list can be found on Wikipedia.

Code

#!/usr/local/bin/python
import sys
from random import randint

def pad(prefix, values):
	prefix = str(prefix)
	i = 0

	for c in prefix:
		values[i] = int(c)
		i = i + 1

	return values

def randomize(values):
	for i in range(0, len(values)):
		values[i] = randint(0, 9)

	return values

def luhn_value(values):
	sum = 0
	i = 0

	while i < len(values):
		if i % 2 == 0:
			value = values[i] * 2

			# Since doubling a single value results in 2 <= i <= 18
			# the sum of the digits is equivolant to subtracting 9
			if value >= 10:
				value = value - 9
		else:
			value = values[i]

		sum = sum + value
		i = i + 1

	return (sum * 9) % 10

def generate(prefix = ""):
	length = 15
	values = [0]*length
	prefix = str(prefix)

	values = randomize(values)
	values = pad(prefix, values)
	check = luhn_value(values)

	return "".join(str(n) for n in values) + str(check)
	
if len(sys.argv) == 2:
	if sys.argv[1].isdigit():
		print(generate(sys.argv[1]))
	else:
		print("Usage: cc.py [prefix]")
else:
	print(generate())

Example

python cc.py 45
4539371684142703

python cc.py  55
5555576731917875