cpython/Lib/crypt.py at master · python-emscripten/cpython · GitHub

Repository navigation

History

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

"""Wrapper to the POSIX crypt library call and associated functionality."""

import sys as _sys

try:

import _crypt

except ModuleNotFoundError:

if _sys.platform == 'win32':

raise ImportError("The crypt module is not supported on Windows")

else:

raise ImportError("The required _crypt module was not built as part of CPython")

import errno

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, *, rounds=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]

if rounds is not None and not isinstance(rounds, int):

raise TypeError(f'{rounds.__class__.__name__} object cannot be '

f'interpreted as an integer')

if not method.ident: # traditional

s = ''

else: # modular

s = f'${method.ident}$'

if method.ident and method.ident[0] == '2': # Blowfish variants

if rounds is None:

log_rounds = 12

else:

log_rounds = int.bit_length(rounds-1)

if rounds != 1 << log_rounds:

raise ValueError('rounds must be a power of 2')

if not 4 <= log_rounds <= 31:

raise ValueError('rounds out of the range 2**4 to 2**31')

s += f'{log_rounds:02d}$'

elif method.ident in ('5', '6'): # SHA-2

if rounds is not None:

if not 1000 <= rounds <= 999_999_999:

raise ValueError('rounds out of the range 1000 to 999_999_999')

s += f'rounds={rounds}$'

elif rounds is not None:

raise ValueError(f"{method} doesn't support the rounds argument")

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

methods = []

def _add_method(name, *args, rounds=None):

method = _Method(name, *args)

globals()['METHOD_' + name] = method

salt = mksalt(method, rounds=rounds)

result = None

try:

result = crypt('', salt)

except OSError as e:

# Not all libc libraries support all encryption methods.

if e.errno == errno.EINVAL:

return False

raise

if result and len(result) == method.total_size:

methods.append(method)

return True

return False

_add_method('SHA512', '6', 16, 106)

_add_method('SHA256', '5', 16, 63)

# Choose the strongest supported version of Blowfish hashing.

# Early versions have flaws. Version 'a' fixes flaws of

# the initial implementation, 'b' fixes flaws of 'a'.

# 'y' is the same as 'b', for compatibility

# with openwall crypt_blowfish.

for _v in 'b', 'y', 'a', '':

if _add_method('BLOWFISH', '2' + _v, 22, 59 + len(_v), rounds=1<<4):

break

_add_method('MD5', '1', 8, 34)

_add_method('CRYPT', None, 2, 13)

del _v, _add_method

cpython/Lib/crypt.py at master · python-emscripten/cpython · GitHub

Repository navigation

Expand file tree

Breadcrumbs

crypt.py

Latest commit

History

Breadcrumbs

crypt.py

File metadata and controls