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)