/usr/share/pyshared/werkzeug/security.py is in python-werkzeug 0.8.3+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | # -*- coding: utf-8 -*-
"""
werkzeug.security
~~~~~~~~~~~~~~~~~
Security related helpers such as secure password hashing tools.
:copyright: (c) 2011 by the Werkzeug Team, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
"""
import os
import hmac
import posixpath
from itertools import izip
from random import SystemRandom
# because the API of hmac changed with the introduction of the
# new hashlib module, we have to support both. This sets up a
# mapping to the digest factory functions and the digest modules
# (or factory functions with changed API)
try:
from hashlib import sha1, md5
_hash_funcs = _hash_mods = {'sha1': sha1, 'md5': md5}
_sha1_mod = sha1
_md5_mod = md5
except ImportError:
import sha as _sha1_mod, md5 as _md5_mod
_hash_mods = {'sha1': _sha1_mod, 'md5': _md5_mod}
_hash_funcs = {'sha1': _sha1_mod.new, 'md5': _md5_mod.new}
SALT_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
_sys_rng = SystemRandom()
_os_alt_seps = list(sep for sep in [os.path.sep, os.path.altsep]
if sep not in (None, '/'))
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 len(a) != len(b):
return False
rv = 0
for x, y in izip(a, b):
rv |= ord(x) ^ ord(y)
return rv == 0
def gen_salt(length):
"""Generate a random string of SALT_CHARS with specified ``length``."""
if length <= 0:
raise ValueError('requested salt of length <= 0')
return ''.join(_sys_rng.choice(SALT_CHARS) for _ in xrange(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
if salt:
if method not in _hash_mods:
return None
if isinstance(salt, unicode):
salt = salt.encode('utf-8')
h = hmac.new(salt, None, _hash_mods[method])
else:
if method not in _hash_funcs:
return None
h = _hash_funcs[method]()
if isinstance(password, unicode):
password = password.encode('utf-8')
h.update(password)
return h.hexdigest()
def generate_password_hash(password, method='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.
:param password: the password to hash
:param method: the hash method to use (``'md5'`` or ``'sha1'``)
:param salt_length: the lengt of the salt in letters
"""
salt = method != 'plain' and gen_salt(salt_length) or ''
h = _hash_internal(method, salt, password)
if h is None:
raise TypeError('invalid method %r' % method)
return '%s$%s$%s' % (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), 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)
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