115 lines
3.8 KiB
Python
115 lines
3.8 KiB
Python
# iban.py - functions for handling International Bank Account Numbers (IBANs)
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#
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# Copyright (C) 2011, 2012, 2013 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""IBAN (International Bank Account Number).
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The IBAN is used to identify bank accounts across national borders. The
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first two letters are a country code. The next two digits are check digits
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for the ISO 7064 Mod 97, 10 checksum. Each country uses its own format
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for the remainder of the number.
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Some countries may also use checksum algorithms within their number but
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this is currently not checked by this number.
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>>> validate('GR16 0110 1050 0000 1054 7023 795')
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'GR1601101050000010547023795'
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>>> validate('BE31435411161155')
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'BE31435411161155'
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>>> compact('GR16 0110 1050 0000 1054 7023 795')
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'GR1601101050000010547023795'
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>>> format('GR1601101050000010547023795')
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'GR16 0110 1050 0000 1054 7023 795'
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"""
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import re
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from stdnum import numdb
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from stdnum.exceptions import *
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from stdnum.iso7064 import mod_97_10
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from stdnum.util import clean
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# our open copy of the IBAN database
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_ibandb = numdb.get('iban')
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# the valid characters we have
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_alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
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# regular expression to check IBAN structure
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_struct_re = re.compile(r'([1-9][0-9]*)!([nac])')
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def compact(number):
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"""Convert the iban number to the minimal representation. This strips the
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number of any valid separators and removes surrounding whitespace."""
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return clean(number, ' -').strip().upper()
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def _to_base10(number):
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"""Prepare the number to its base10 representation (also moving the
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check digits to the end) so it can be checked with the ISO 7064
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Mod 97, 10 algorithm."""
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# TODO: find out whether this should be in the mod_97_10 module
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return ''.join(str(_alphabet.index(x)) for x in number[4:] + number[:4])
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def _struct_to_re(structure):
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"""Convert an IBAN structure to a refular expression that can be used
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to validate the number."""
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def conv(match):
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chars = {
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'n': '[0-9]',
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'a': '[A-Z]',
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'c': '[A-Za-z0-9]',
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}[match.group(2)]
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return '%s{%s}' % (chars, match.group(1))
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return re.compile('^%s$' % _struct_re.sub(conv, structure))
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def validate(number):
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"""Checks to see if the number provided is a valid IBAN."""
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number = compact(number)
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try:
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test_number = _to_base10(number)
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except Exception:
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raise InvalidFormat()
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# ensure that checksum is valid
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mod_97_10.validate(test_number)
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# look up the number
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info = _ibandb.info(number)
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# check if the bban part of number has the correct structure
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bban = number[4:]
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if not _struct_to_re(info[0][1].get('bban', '')).match(bban):
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raise InvalidFormat()
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# return the compact representation
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return number
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def is_valid(number):
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"""Checks to see if the number provided is a valid IBAN."""
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try:
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return bool(validate(number))
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except ValidationError:
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return False
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def format(number, separator=' '):
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"""Reformat the passed number to the space-separated format."""
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number = compact(number)
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return separator.join(number[i:i + 4] for i in range(0, len(number), 4))
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