Python IBAN Checker

check_iban.py

# Based on http://codereview.stackexchange.com/questions/135366/python-iban-validation

import string

def is_iban(unchecked_iban):

  LETTERS = {ord(d): str(i) for i, d in enumerate(string.digits + string.ascii_uppercase)}


  def _number_iban(iban):
      return (iban[4:] + iban[:4]).translate(LETTERS)


  def generate_iban_check_digits(iban):
      number_iban = _number_iban(iban[:2] + '00' + iban[4:])
      return '{:0>2}'.format(98 - (int(number_iban) % 97))


  def valid_iban(iban):
      return int(_number_iban(iban)) % 97 == 1

  return generate_iban_check_digits(unchecked_iban) == unchecked_iban[2:4] and valid_iban(unchecked_iban)

          

def generate_valid_iban():
    import random, string

    def is_iban(unchecked_iban):

        LETTERS = {ord(d): str(i) for i, d in enumerate(string.digits + string.ascii_uppercase)}

        def _number_iban(iban):
            return (iban[4:] + iban[:4]).translate(LETTERS)

        def generate_iban_check_digits(iban):
            number_iban = _number_iban(iban[:2] + '00' + iban[4:])
            return '{:0>2}'.format(98 - (int(number_iban) % 97))

        def valid_iban(iban):
            return int(_number_iban(iban)) % 97 == 1

        return generate_iban_check_digits(unchecked_iban) == unchecked_iban[2:4] and valid_iban(unchecked_iban)

    def bank_ck(ktn):

        ktn = list(map(lambda x: int(x), ktn))[::-1]
        generator = [2, 3, 4, 5, 6, 7, 8, 9, 3]
        rest = sum(map(lambda x: x[0] * x[1], zip(generator, ktn))) % 11
        if rest == 1:
            return 0
        if rest == 0:
            return 0
        return 11 - rest


    while True:
        blz = "13050000"
        ktnr = str(random.randint(111111111, 999999999))
        ktnr = "{}{}".format(ktnr, bank_ck(ktnr))
        iban = "DE{check}{blz}{ran}".format(check=random.randint(11, 99), blz=blz, ran=ktnr)
        if is_iban(iban):
            print(iban)
            break
    return iban

it doesn't account for valid ISO2 country names