"""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, METHOD_CRYPT): _result = crypt('', _method) if _result and len(_result) == _method.total_size: methods.append(_method) del _result, _method