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63 lines
1.8 KiB
Python
63 lines
1.8 KiB
Python
"""Wrapper to the POSIX crypt library call and associated functionality."""
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import _crypt
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import string as _string
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from random import SystemRandom as _SystemRandom
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from collections import namedtuple as _namedtuple
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_saltchars = _string.ascii_letters + _string.digits + './'
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_sr = _SystemRandom()
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class _Method(_namedtuple('_Method', 'name ident salt_chars total_size')):
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"""Class representing a salt method per the Modular Crypt Format or the
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legacy 2-character crypt method."""
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def __repr__(self):
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return '<crypt.METHOD_{}>'.format(self.name)
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def mksalt(method=None):
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"""Generate a salt for the specified method.
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If not specified, the strongest available method will be used.
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"""
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if method is None:
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method = methods[0]
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s = '${}$'.format(method.ident) if method.ident else ''
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s += ''.join(_sr.sample(_saltchars, method.salt_chars))
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return s
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def crypt(word, salt=None):
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"""Return a string representing the one-way hash of a password, with a salt
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prepended.
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If ``salt`` is not specified or is ``None``, the strongest
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available method will be selected and a salt generated. Otherwise,
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``salt`` may be one of the ``crypt.METHOD_*`` values, or a string as
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returned by ``crypt.mksalt()``.
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"""
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if salt is None or isinstance(salt, _Method):
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salt = mksalt(salt)
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return _crypt.crypt(word, salt)
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# available salting/crypto methods
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METHOD_CRYPT = _Method('CRYPT', None, 2, 13)
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METHOD_MD5 = _Method('MD5', '1', 8, 34)
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METHOD_SHA256 = _Method('SHA256', '5', 16, 63)
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METHOD_SHA512 = _Method('SHA512', '6', 16, 106)
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methods = []
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for _method in (METHOD_SHA512, METHOD_SHA256, METHOD_MD5):
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_result = crypt('', _method)
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if _result and len(_result) == _method.total_size:
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methods.append(_method)
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methods.append(METHOD_CRYPT)
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del _result, _method
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