135 lines
4.6 KiB
Python
135 lines
4.6 KiB
Python
# iban.py - functions for handling International Bank Account Numbers (IBANs)
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#
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# Copyright (C) 2011-2018 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 only checked for a few countries.
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More information:
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* https://en.wikipedia.org/wiki/International_Bank_Account_Number
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* https://www.swift.com/products_services/bic_and_iban_format_registration_iban_format_r
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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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>>> calc_check_digits('BExx435411161155')
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'31'
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"""
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from __future__ import annotations
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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 NumberValidationModule, clean, get_cc_module
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# our open copy of the IBAN database
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_ibandb = numdb.get('iban')
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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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# cache of country codes to modules
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_country_modules = {}
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def compact(number: str) -> str:
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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 calc_check_digits(number: str) -> str:
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"""Calculate the check digits that should be put in the number to make
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it valid. Check digits in the supplied number are ignored."""
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number = compact(number)
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return mod_97_10.calc_check_digits(number[4:] + number[:2])
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def _struct_to_re(structure: str) -> re.Pattern[str]:
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"""Convert an IBAN structure to a regular expression that can be used
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to validate the number."""
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def conv(match: re.Match[str]) -> str:
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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 _get_cc_module(cc: str) -> NumberValidationModule | None:
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"""Get the IBAN module based on the country code."""
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cc = cc.lower()
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if cc not in _country_modules:
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_country_modules[cc] = get_cc_module(cc, 'iban')
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return _country_modules[cc]
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def validate(number: str, check_country: bool = True) -> str:
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"""Check if the number provided is a valid IBAN. The country-specific
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check can be disabled with the check_country argument."""
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number = compact(number)
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# ensure that checksum is valid
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mod_97_10.validate(number[4:] + number[:4])
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# look up the number
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info = _ibandb.info(number)
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if not info[0][1]:
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raise InvalidComponent()
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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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# check the country-specific module if it exists
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if check_country:
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module = _get_cc_module(number[:2])
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if module:
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module.validate(number)
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# return the compact representation
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return number
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def is_valid(number: str, check_country: bool = True) -> bool:
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"""Check if the number provided is a valid IBAN."""
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try:
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return bool(validate(number, check_country=check_country))
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except ValidationError:
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return False
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def format(number: str, separator: str = ' ') -> str:
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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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