CNPJ (Brazilian tax id) format validation

validate_cnpj.py

#-------------------------------------------------------------------------------
# Name:        validate_cnpj
# Purpose:     check formal validity of a cnpj number (brazilian tax id)
#              this only checks if the digits match, not if the number is
#              valid at Receita Federal (Brazilian IRS)
#
# Author:      Paulo Scardine <[email protected]>
#
# Created:     26/11/2012
# Copyright:   (c) PauloS 2012
# Licence:     BSD
#-------------------------------------------------------------------------------
#!/usr/bin/env python

def xtend_validate_cnpj(cnpj):
    # Filter out non digits and pad with 0 until length is 15
    cnpj = ''.join([ c for c in cnpj if c in '0123456789']).rjust(15, '0')
    # If more then 15 digits or all 0s, reject
    if len(cnpj) != 15 or cnpj == '0' * 15: return False
    # Check first digit
    j = 2; s1 = 0
    for i in range(12, -1, -1):
        s1 += int(cnpj[i]) * j
        j += 1
        if j > 9: j = 2
    r = s1 % 11
    if int(cnpj[13]) != (0 if r < 2 else 11 - r): return False
    # Check second digit
    j = 2; s2 = 0
    for i in range(13, -1, -1):
        s2 += int(cnpj[i]) * j
        j += 1
        if j > 9: j = 2
    r = s2 % 11
    return int(cnpj[14]) == (0 if r < 2 else 11 - r)

def main():
    for cnpj in ('012345678000100', '012345678000190', '012345678000195'):
        print cnpj, ':',
        print xtend_validate_cnpj(cnpj)

if __name__ == '__main__':
    main()