264 lines
8.8 KiB
Python
264 lines
8.8 KiB
Python
# -*- coding: utf-8 -*-
|
|
"""
|
|
werkzeug.security
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
Security related helpers such as secure password hashing tools.
|
|
|
|
:copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
|
|
:license: BSD, see LICENSE for more details.
|
|
"""
|
|
import os
|
|
import hmac
|
|
import hashlib
|
|
import posixpath
|
|
import codecs
|
|
from struct import Struct
|
|
from random import SystemRandom
|
|
from operator import xor
|
|
from itertools import starmap
|
|
|
|
from werkzeug._compat import range_type, PY2, text_type, izip, to_bytes, \
|
|
string_types, to_native
|
|
|
|
|
|
SALT_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
|
|
DEFAULT_PBKDF2_ITERATIONS = 1000
|
|
|
|
|
|
_pack_int = Struct('>I').pack
|
|
_builtin_safe_str_cmp = getattr(hmac, 'compare_digest', None)
|
|
_sys_rng = SystemRandom()
|
|
_os_alt_seps = list(sep for sep in [os.path.sep, os.path.altsep]
|
|
if sep not in (None, '/'))
|
|
|
|
|
|
def _find_hashlib_algorithms():
|
|
algos = getattr(hashlib, 'algorithms', None)
|
|
if algos is None:
|
|
algos = ('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512')
|
|
rv = {}
|
|
for algo in algos:
|
|
func = getattr(hashlib, algo, None)
|
|
if func is not None:
|
|
rv[algo] = func
|
|
return rv
|
|
_hash_funcs = _find_hashlib_algorithms()
|
|
|
|
|
|
def pbkdf2_hex(data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS,
|
|
keylen=None, hashfunc=None):
|
|
"""Like :func:`pbkdf2_bin`, but returns a hex-encoded string.
|
|
|
|
.. versionadded:: 0.9
|
|
|
|
:param data: the data to derive.
|
|
:param salt: the salt for the derivation.
|
|
:param iterations: the number of iterations.
|
|
:param keylen: the length of the resulting key. If not provided,
|
|
the digest size will be used.
|
|
:param hashfunc: the hash function to use. This can either be the
|
|
string name of a known hash function, or a function
|
|
from the hashlib module. Defaults to sha1.
|
|
"""
|
|
rv = pbkdf2_bin(data, salt, iterations, keylen, hashfunc)
|
|
return to_native(codecs.encode(rv, 'hex_codec'))
|
|
|
|
|
|
_has_native_pbkdf2 = hasattr(hashlib, 'pbkdf2_hmac')
|
|
|
|
|
|
def pbkdf2_bin(data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS,
|
|
keylen=None, hashfunc=None):
|
|
"""Returns a binary digest for the PBKDF2 hash algorithm of `data`
|
|
with the given `salt`. It iterates `iterations` times and produces a
|
|
key of `keylen` bytes. By default, SHA-1 is used as hash function;
|
|
a different hashlib `hashfunc` can be provided.
|
|
|
|
.. versionadded:: 0.9
|
|
|
|
:param data: the data to derive.
|
|
:param salt: the salt for the derivation.
|
|
:param iterations: the number of iterations.
|
|
:param keylen: the length of the resulting key. If not provided
|
|
the digest size will be used.
|
|
:param hashfunc: the hash function to use. This can either be the
|
|
string name of a known hash function or a function
|
|
from the hashlib module. Defaults to sha1.
|
|
"""
|
|
if isinstance(hashfunc, string_types):
|
|
hashfunc = _hash_funcs[hashfunc]
|
|
elif not hashfunc:
|
|
hashfunc = hashlib.sha1
|
|
data = to_bytes(data)
|
|
salt = to_bytes(salt)
|
|
|
|
# If we're on Python with pbkdf2_hmac we can try to use it for
|
|
# compatible digests.
|
|
if _has_native_pbkdf2:
|
|
_test_hash = hashfunc()
|
|
if hasattr(_test_hash, 'name') and \
|
|
_test_hash.name in _hash_funcs:
|
|
return hashlib.pbkdf2_hmac(_test_hash.name,
|
|
data, salt, iterations,
|
|
keylen)
|
|
|
|
mac = hmac.HMAC(data, None, hashfunc)
|
|
if not keylen:
|
|
keylen = mac.digest_size
|
|
def _pseudorandom(x, mac=mac):
|
|
h = mac.copy()
|
|
h.update(x)
|
|
return bytearray(h.digest())
|
|
buf = bytearray()
|
|
for block in range_type(1, -(-keylen // mac.digest_size) + 1):
|
|
rv = u = _pseudorandom(salt + _pack_int(block))
|
|
for i in range_type(iterations - 1):
|
|
u = _pseudorandom(bytes(u))
|
|
rv = bytearray(starmap(xor, izip(rv, u)))
|
|
buf.extend(rv)
|
|
return bytes(buf[:keylen])
|
|
|
|
|
|
def safe_str_cmp(a, b):
|
|
"""This function compares strings in somewhat constant time. This
|
|
requires that the length of at least one string is known in advance.
|
|
|
|
Returns `True` if the two strings are equal, or `False` if they are not.
|
|
|
|
.. versionadded:: 0.7
|
|
"""
|
|
if isinstance(a, text_type):
|
|
a = a.encode('utf-8')
|
|
if isinstance(b, text_type):
|
|
b = b.encode('utf-8')
|
|
|
|
if _builtin_safe_str_cmp is not None:
|
|
return _builtin_safe_str_cmp(a, b)
|
|
|
|
if len(a) != len(b):
|
|
return False
|
|
|
|
rv = 0
|
|
if PY2:
|
|
for x, y in izip(a, b):
|
|
rv |= ord(x) ^ ord(y)
|
|
else:
|
|
for x, y in izip(a, b):
|
|
rv |= x ^ y
|
|
|
|
return rv == 0
|
|
|
|
|
|
def gen_salt(length):
|
|
"""Generate a random string of SALT_CHARS with specified ``length``."""
|
|
if length <= 0:
|
|
raise ValueError('Salt length must be positive')
|
|
return ''.join(_sys_rng.choice(SALT_CHARS) for _ in range_type(length))
|
|
|
|
|
|
def _hash_internal(method, salt, password):
|
|
"""Internal password hash helper. Supports plaintext without salt,
|
|
unsalted and salted passwords. In case salted passwords are used
|
|
hmac is used.
|
|
"""
|
|
if method == 'plain':
|
|
return password, method
|
|
|
|
if isinstance(password, text_type):
|
|
password = password.encode('utf-8')
|
|
|
|
if method.startswith('pbkdf2:'):
|
|
args = method[7:].split(':')
|
|
if len(args) not in (1, 2):
|
|
raise ValueError('Invalid number of arguments for PBKDF2')
|
|
method = args.pop(0)
|
|
iterations = args and int(args[0] or 0) or DEFAULT_PBKDF2_ITERATIONS
|
|
is_pbkdf2 = True
|
|
actual_method = 'pbkdf2:%s:%d' % (method, iterations)
|
|
else:
|
|
is_pbkdf2 = False
|
|
actual_method = method
|
|
|
|
hash_func = _hash_funcs.get(method)
|
|
if hash_func is None:
|
|
raise TypeError('invalid method %r' % method)
|
|
|
|
if is_pbkdf2:
|
|
if not salt:
|
|
raise ValueError('Salt is required for PBKDF2')
|
|
rv = pbkdf2_hex(password, salt, iterations,
|
|
hashfunc=hash_func)
|
|
elif salt:
|
|
if isinstance(salt, text_type):
|
|
salt = salt.encode('utf-8')
|
|
rv = hmac.HMAC(salt, password, hash_func).hexdigest()
|
|
else:
|
|
h = hash_func()
|
|
h.update(password)
|
|
rv = h.hexdigest()
|
|
return rv, actual_method
|
|
|
|
|
|
def generate_password_hash(password, method='pbkdf2:sha1', salt_length=8):
|
|
"""Hash a password with the given method and salt with with a string of
|
|
the given length. The format of the string returned includes the method
|
|
that was used so that :func:`check_password_hash` can check the hash.
|
|
|
|
The format for the hashed string looks like this::
|
|
|
|
method$salt$hash
|
|
|
|
This method can **not** generate unsalted passwords but it is possible
|
|
to set the method to plain to enforce plaintext passwords. If a salt
|
|
is used, hmac is used internally to salt the password.
|
|
|
|
If PBKDF2 is wanted it can be enabled by setting the method to
|
|
``pbkdf2:method:iterations`` where iterations is optional::
|
|
|
|
pbkdf2:sha1:2000$salt$hash
|
|
pbkdf2:sha1$salt$hash
|
|
|
|
:param password: the password to hash.
|
|
:param method: the hash method to use (one that hashlib supports). Can
|
|
optionally be in the format ``pbkdf2:<method>[:iterations]``
|
|
to enable PBKDF2.
|
|
:param salt_length: the length of the salt in letters.
|
|
"""
|
|
salt = method != 'plain' and gen_salt(salt_length) or ''
|
|
h, actual_method = _hash_internal(method, salt, password)
|
|
return '%s$%s$%s' % (actual_method, salt, h)
|
|
|
|
|
|
def check_password_hash(pwhash, password):
|
|
"""check a password against a given salted and hashed password value.
|
|
In order to support unsalted legacy passwords this method supports
|
|
plain text passwords, md5 and sha1 hashes (both salted and unsalted).
|
|
|
|
Returns `True` if the password matched, `False` otherwise.
|
|
|
|
:param pwhash: a hashed string like returned by
|
|
:func:`generate_password_hash`.
|
|
:param password: the plaintext password to compare against the hash.
|
|
"""
|
|
if pwhash.count('$') < 2:
|
|
return False
|
|
method, salt, hashval = pwhash.split('$', 2)
|
|
return safe_str_cmp(_hash_internal(method, salt, password)[0], hashval)
|
|
|
|
|
|
def safe_join(directory, filename):
|
|
"""Safely join `directory` and `filename`. If this cannot be done,
|
|
this function returns ``None``.
|
|
|
|
:param directory: the base directory.
|
|
:param filename: the untrusted filename relative to that directory.
|
|
"""
|
|
filename = posixpath.normpath(filename)
|
|
for sep in _os_alt_seps:
|
|
if sep in filename:
|
|
return None
|
|
if os.path.isabs(filename) or filename.startswith('../'):
|
|
return None
|
|
return os.path.join(directory, filename)
|