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