67 lines
2.1 KiB
Python
67 lines
2.1 KiB
Python
# mod_97_10.py - functions for performing the ISO 7064 Mod 97, 10 algorithm
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#
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# Copyright (C) 2010, 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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"""The ISO 7064 Mod 97, 10 algorithm.
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The Mod 97, 10 algorithm evaluates the whole number as an integer which is
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valid if the number modulo 97 is 1. As such it has two check digits.
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>>> calc_check_digits('99991234567890121414')
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'90'
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>>> validate('9999123456789012141490')
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'9999123456789012141490'
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>>> calc_check_digits('4354111611551114')
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'31'
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>>> validate('08686001256515001121751')
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'08686001256515001121751'
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>>> calc_check_digits('22181321402534321446701611')
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'35'
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"""
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from stdnum.exceptions import *
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def checksum(number):
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"""Calculate the checksum. A valid number should have a checksum of 1."""
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return int(number) % 97
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def calc_check_digits(number):
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"""With the provided number, calculate the extra digits that should be
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appended to make it a valid number."""
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return '%02d' % ((98 - 100 * checksum(number)) % 97)
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def validate(number):
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"""Checks whether the check digit is valid."""
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try:
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valid = checksum(number) == 1
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except:
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raise InvalidFormat()
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if not valid:
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raise InvalidChecksum()
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return number
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def is_valid(number):
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"""Checks whether the check digit is valid."""
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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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