mirror of https://gerrit.osmocom.org/pysim
utils: Add function to verify Luhn check digits and to sanitize ICCIDs
Change-Id: I7812420cf97984dd834fca6a38c5e5ae113243cb
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@ -9,7 +9,7 @@ import string
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import datetime
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import argparse
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from io import BytesIO
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from typing import Optional, List, Dict, Any, Tuple, NewType
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from typing import Optional, List, Dict, Any, Tuple, NewType, Union
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# Copyright (C) 2009-2010 Sylvain Munaut <tnt@246tNt.com>
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# Copyright (C) 2021 Harald Welte <laforge@osmocom.org>
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@ -446,6 +446,30 @@ def dec_iccid(ef: Hexstr) -> str:
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def enc_iccid(iccid: str) -> Hexstr:
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return swap_nibbles(rpad(iccid, 20))
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def sanitize_iccid(iccid: Union[int, str]) -> str:
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iccid = str(iccid)
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if len(iccid) < 18:
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raise ValueError('ICCID input value must be at least 18 digits')
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if len(iccid) > 20:
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raise ValueError('ICCID input value must be at most 20 digits')
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if len(iccid) == 18:
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# 18 digits means we must add a luhn check digit to reach 19 digits
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iccid += str(calculate_luhn(iccid))
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if len(iccid) == 20:
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# 20 digits means we're actually exceeding E.118 by one digit, and
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# the luhn check digit must already be included
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verify_luhn(iccid)
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if len(iccid) == 19:
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# 19 digits means that it's either an in-spec 19-digits ICCID with
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# its luhn check digit already present, or it's an out-of-spec 20-digit
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# ICCID without that check digit...
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try:
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verify_luhn(iccid)
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except ValueError:
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# 19th digit was not luhn check digit; we must add it
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iccid += str(calculate_luhn(iccid))
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return iccid
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def enc_plmn(mcc: Hexstr, mnc: Hexstr) -> Hexstr:
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"""Converts integer MCC/MNC into 3 bytes for EF"""
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@ -606,6 +630,11 @@ def calculate_luhn(cc) -> int:
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for d in num[::-2]]) % 10
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return 0 if check_digit == 10 else check_digit
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def verify_luhn(digits: str):
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"""Verify the Luhn check digit; raises ValueError if it is incorrect."""
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cd = calculate_luhn(digits[:-1])
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if str(cd) != digits[-1]:
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raise ValueError('Luhn check digit mismatch: should be %s but is %s' % (str(cd), digits[-1]))
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def mcc_from_imsi(imsi: str) -> Optional[str]:
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"""
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@ -236,5 +236,22 @@ class TestDgiTlv(unittest.TestCase):
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self.assertEqual(utils.dgi_parse_len(b'\xfe\x0b'), (254, b'\x0b'))
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self.assertEqual(utils.dgi_parse_len(b'\xff\x00\xff\x0b'), (255, b'\x0b'))
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class TestLuhn(unittest.TestCase):
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def test_verify(self):
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utils.verify_luhn('8988211000000530082')
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def test_encode(self):
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self.assertEqual(utils.calculate_luhn('898821100000053008'), 2)
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def test_sanitize_iccid(self):
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# 19 digits with correct luhn; we expect no change
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self.assertEqual(utils.sanitize_iccid('8988211000000530082'), '8988211000000530082')
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# 20 digits with correct luhn; we expect no change
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self.assertEqual(utils.sanitize_iccid('89882110000005300811'), '89882110000005300811')
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# 19 digits without correct luhn; we expect check digit to be added
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self.assertEqual(utils.sanitize_iccid('8988211000000530081'), '89882110000005300811')
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# 18 digits; we expect luhn check digit to be added
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self.assertEqual(utils.sanitize_iccid('898821100000053008'), '8988211000000530082')
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if __name__ == "__main__":
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unittest.main()
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