1 files changed, 62 insertions, 0 deletions
diff --git a/Lib/crypt.py b/Lib/crypt.py
new file mode 100644
index 0000000000..49ab96e140
--- /dev/null
+++ b/Lib/crypt.py
@@ -0,0 +1,62 @@
+"""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