# meid.py - functions for handling Mobile Equipment Identifiers (MEIDs)
#
# Copyright (C) 2010-2017 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""MEID (Mobile Equipment Identifier).
The Mobile Equipment Identifier is used to identify a physical piece of
CDMA mobile station equipment.
>>> validate('AF 01 23 45 0A BC DE C')
'AF0123450ABCDE'
>>> validate('29360 87365 0070 3710 0')
'AF0123450ABCDE'
>>> validate('29360 87365 0070 3710 0', strip_check_digit=False)
'AF0123450ABCDEC'
>>> validate('29360 87365 0070 3710 1')
Traceback (most recent call last):
...
InvalidChecksum: ...
>>> format('af0123450abcDEC', add_check_digit=True)
'AF 01 23 45 0A BC DE C'
>>> format('af0123450abcDEC', format='dec', add_check_digit=True)
'29360 87365 0070 3710 0'
"""
from stdnum.exceptions import *
from stdnum.util import clean, isdigits
_hex_alphabet = '0123456789ABCDEF'
def _cleanup(number):
"""Remove any grouping information from the number and removes surrounding
whitespace."""
return clean(number, ' -').strip().upper()
def _ishex(number):
for x in number:
if x not in _hex_alphabet:
return False
return True
def _parse(number):
number = _cleanup(number)
if len(number) in (14, 15):
# 14 or 15 digit hex representation
if not _ishex(number):
raise InvalidFormat()
return number[0:14], number[14:]
elif len(number) in (18, 19):
# 18-digit decimal representation
if not isdigits(number):
raise InvalidFormat()
return number[0:18], number[18:]
else:
raise InvalidLength()
def calc_check_digit(number):
"""Calculate the check digit for the number. The number should not
already have a check digit."""
# both the 18-digit decimal format and the 14-digit hex format
# containing only decimal digits should use the decimal Luhn check
from stdnum import luhn
if isdigits(number):
return luhn.calc_check_digit(number)
else:
return luhn.calc_check_digit(number, alphabet=_hex_alphabet)
def compact(number, strip_check_digit=True):
"""Convert the MEID number to the minimal (hexadecimal) representation.
This strips grouping information, removes surrounding whitespace and
converts to hexadecimal if needed. If the check digit is to be preserved
and conversion is done a new check digit is recalculated."""
# first parse the number
number, cd = _parse(number)
# strip check digit if needed
if strip_check_digit:
cd = ''
# convert to hex if needed
if len(number) == 18:
number = '%08X%06X' % (int(number[0:10]), int(number[10:18]))
if cd:
cd = calc_check_digit(number)
# put parts back together again
return number + cd
def _bit_length(n):
"""Return the number of bits necessary to store the number in binary."""
try:
return n.bit_length()
except AttributeError: # pragma: no cover (Python 2.6 only)
import math
return int(math.log(n, 2)) + 1
def validate(number, strip_check_digit=True):
"""Check if the number is a valid MEID number. This converts the
representation format of the number (if it is decimal it is not converted
to hexadecimal)."""
from stdnum import luhn
# first parse the number
number, cd = _parse(number)
if len(number) == 18:
# decimal format can be easily determined
if cd:
luhn.validate(number + cd)
# convert to hex
manufacturer_code = int(number[0:10])
serial_num = int(number[10:18])
if _bit_length(manufacturer_code) > 32 or _bit_length(serial_num) > 24:
raise InvalidComponent()
number = '%08X%06X' % (manufacturer_code, serial_num)
cd = calc_check_digit(number)
elif isdigits(number):
# if the remaining hex format is fully decimal it is an IMEI number
from stdnum import imei
imei.validate(number + cd)
else:
# normal hex Luhn validation
if cd:
luhn.validate(number + cd, alphabet=_hex_alphabet)
if strip_check_digit:
cd = ''
return number + cd
def is_valid(number):
"""Check if the number is a valid MEID number."""
try:
return bool(validate(number))
except ValidationError:
return False
def format(number, separator=' ', format=None, add_check_digit=False):
"""Reformat the number to the standard presentation format. The separator
used can be provided. If the format is specified (either 'hex' or 'dec')
the number is reformatted in that format, otherwise the current
representation is kept. If add_check_digit is True a check digit will be
added if it is not present yet."""
# first parse the number
number, cd = _parse(number)
# format conversions if needed
if format == 'dec' and len(number) == 14:
# convert to decimal
number = '%010d%08d' % (int(number[0:8], 16), int(number[8:14], 16))
if cd:
cd = calc_check_digit(number)
elif format == 'hex' and len(number) == 18:
# convert to hex
number = '%08X%06X' % (int(number[0:10]), int(number[10:18]))
if cd:
cd = calc_check_digit(number)
# see if we need to add a check digit
if add_check_digit and not cd:
cd = calc_check_digit(number)
# split number according to format
if len(number) == 14:
number = [number[i * 2:i * 2 + 2]
for i in range(7)] + [cd]
else:
number = (number[:5], number[5:10], number[10:14], number[14:], cd)
return separator.join(x for x in number if x)
def to_binary(number):
"""Convert the number to its binary representation (without the check
digit)."""
from binascii import a2b_hex
return a2b_hex(compact(number, strip_check_digit=True))
def to_pseudo_esn(number):
"""Convert the provided MEID to a pseudo ESN (pESN). The ESN is returned
in compact hexadecimal representation."""
import hashlib
# return the last 6 digits of the SHA1 hash prefixed with the reserved
# manufacturer code
return '80' + hashlib.sha1(to_binary(number)).hexdigest()[-6:].upper()