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-rw-r--r--Lib/crypt.py62
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diff --git a/Lib/crypt.py b/Lib/crypt.py
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+++ b/Lib/crypt.py
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+"""Wrapper to the POSIX crypt library call and associated functionality."""
+
+import _crypt
+import string
+from random import choice
+from collections import namedtuple
+
+
+_saltchars = string.ascii_letters + string.digits + './'
+
+
+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(choice(_saltchars) for _ 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