IBAN validating code

Wed 06 February 2008 | tags: python

Recently i needed to validate some IBAN numbers (International Bank Account Number). I quick search revealed the wikipedia article on the subject.

Though i had initially hacked up a Greek-only IBAN validator i though it might be of use to other people as well and modified it to validate  every possible IBAN (as long as the wikipedia article is complete).

 

So here it is:

 

#!/usr/bin/python
# -*- coding: utf-8

# iban.py
# http://kill9.eu/
#
# Copyright (C) 2008 Konstantinos Metaxas 
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation; version 2 only.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

import string

class IBAN(object):

    def __init__(self,iban):
        """Represents an IBAN number.
        iban must be supplied as a string"""
        self.iban = iban.strip().upper()
        #List retrieved from http://en.wikipedia.org/wiki/IBAN
        self.error_list = []
        self.country_length_table = {
                'AD':('Andora',24),
                'AT':('Austria',20),
                'BE':('Belgium',16),
                'BA':('Bosnia and Hetzegovina',20),
                'BG':('Bulgaria',22),
                'HR':('Croatia',21),
                'CY':('Cyprus',28),
                'CZ':('Czech Republic',24),
                'DK':('Denmark',18),
                'EE':('Estonia',20),
                'FO':('Faroe Islands',18),
                'FI':('Finland',18),
                'FR':('France',27),
                'DE':('Germany',22),
                'GI':('Gibraltar',23),
                'GR':('Greece',27),
                'GL':('Greenland',18),
                'HU':('Hungary',28),
                'IS':('Iceland',26),
                'IE':('Republic of Ireland',22),
                'IL':('Israel',23),
                'IT':('Italy',27),
                'LV':('Latvia',21),
                'LI':('Liechtenstein',21),
                'LT':('Lithuania',20),
                'LU':('Luxembourg',20),
                'MK':('FYROM',19),
                'MT':('Malta',31),
                'MC':('Monaco',27),
                'ME':('Montenegro',22),
                'MA':('Morocco',24),
                'NL':('Netherlands',18),
                'NO':('Norway',15),
                'PL':('Poland',28),
                'PT':('Portugal',25),
                'RO':('Romania',24),
                'SM':('San Marino',27),
                'RS':('Serbia',22),
                'SK':('Slovakia',24),
                'SI':('Slovenia',19),
                'ES':('Spain',24),
                'SE':('Sweden',24),
                'CH':('Switzerland',21),
                'TR':('Turkey',26),
                'TN':('Tunisia',24),
                'GB':('United Kingdom',22),

                }

    def is_valid(self):
        """checks if it is a valid IBAN"""

        if not self._is_valid_for_countrycode():
            return False
        if not self._swift_check():
            return False
        return True

    def _is_valid_for_countrycode(self):
        code = self.iban[:2]
        try:
            max_length = self.country_length_table[code][1]
        except KeyError:
            return False
        if len(self.iban) != max_length:
            return False
        else:
            return True

    def _swift_check(self):
        """
        http://en.wikipedia.org/wiki/IBAN
        """
        head_to_tail_iban = self.iban[4:] + self.iban[:4]
        numerical_ascii_map = dict( zip(string.ascii_uppercase,range(10,36)) )

        translated_iban = ""
        for c in head_to_tail_iban:
            if c in numerical_ascii_map:
                translated_iban += str(numerical_ascii_map[c])
            else:
                translated_iban += c

        try:
            integer_iban = int(translated_iban)
        except ValueError:
            return False

        modulo = integer_iban % 97

        if modulo == 1:
            return True
        else:
            return False

Using it as as simple as:

 

Python 2.5.1 (r251:54863, Oct 14 2007, 19:24:49)
[GCC 4.2.2 (Gentoo 4.2.2 p1.0)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import iban
>>> myIBAN = iban.IBAN('GRXXXXXXXXXXXXXXXXXX') # Actual IBAN omitted for privacy reasons
>>> myIBAN.is_valid()
True

 

It should be easy to make it into a custom Django Form Field , and i might post the relevant code later.

Comments !

blogroll

social