Skip to content
Find file
Fetching contributors…
Cannot retrieve contributors at this time
403 lines (325 sloc) 12.7 KB
import hashlib
from django.dispatch import receiver
from django.conf import settings
from django.test.signals import setting_changed
from django.utils import importlib
from django.utils.datastructures import SortedDict
from django.utils.encoding import smart_str
from django.core.exceptions import ImproperlyConfigured
from django.utils.crypto import (
pbkdf2, constant_time_compare, get_random_string)
from django.utils.translation import ugettext_noop as _
UNUSABLE_PASSWORD = '!' # This will never be a valid encoded hash
HASHERS = None # lazily loaded from PASSWORD_HASHERS
PREFERRED_HASHER = None # defaults to first item in PASSWORD_HASHERS
@receiver(setting_changed)
def reset_hashers(**kwargs):
if kwargs['setting'] == 'PASSWORD_HASHERS':
global HASHERS, PREFERRED_HASHER
HASHERS = None
PREFERRED_HASHER = None
def is_password_usable(encoded):
return (encoded is not None and encoded != UNUSABLE_PASSWORD)
def check_password(password, encoded, setter=None, preferred='default'):
"""
Returns a boolean of whether the raw password matches the three
part encoded digest.
If setter is specified, it'll be called when you need to
regenerate the password.
"""
if not password or not is_password_usable(encoded):
return False
preferred = get_hasher(preferred)
raw_password = password
password = smart_str(password)
encoded = smart_str(encoded)
if len(encoded) == 32 and '$' not in encoded:
hasher = get_hasher('unsalted_md5')
else:
algorithm = encoded.split('$', 1)[0]
hasher = get_hasher(algorithm)
must_update = hasher.algorithm != preferred.algorithm
is_correct = hasher.verify(password, encoded)
if setter and is_correct and must_update:
setter(raw_password)
return is_correct
def make_password(password, salt=None, hasher='default'):
"""
Turn a plain-text password into a hash for database storage
Same as encode() but generates a new random salt. If
password is None or blank then UNUSABLE_PASSWORD will be
returned which disallows logins.
"""
if not password:
return UNUSABLE_PASSWORD
hasher = get_hasher(hasher)
password = smart_str(password)
if not salt:
salt = hasher.salt()
salt = smart_str(salt)
return hasher.encode(password, salt)
def load_hashers(password_hashers=None):
global HASHERS
global PREFERRED_HASHER
hashers = []
if not password_hashers:
password_hashers = settings.PASSWORD_HASHERS
for backend in password_hashers:
try:
mod_path, cls_name = backend.rsplit('.', 1)
mod = importlib.import_module(mod_path)
hasher_cls = getattr(mod, cls_name)
except (AttributeError, ImportError, ValueError):
raise ImproperlyConfigured("hasher not found: %s" % backend)
hasher = hasher_cls()
if not getattr(hasher, 'algorithm'):
raise ImproperlyConfigured("hasher doesn't specify an "
"algorithm name: %s" % backend)
hashers.append(hasher)
HASHERS = dict([(hasher.algorithm, hasher) for hasher in hashers])
PREFERRED_HASHER = hashers[0]
def get_hasher(algorithm='default'):
"""
Returns an instance of a loaded password hasher.
If algorithm is 'default', the default hasher will be returned.
This function will also lazy import hashers specified in your
settings file if needed.
"""
if hasattr(algorithm, 'algorithm'):
return algorithm
elif algorithm == 'default':
if PREFERRED_HASHER is None:
load_hashers()
return PREFERRED_HASHER
else:
if HASHERS is None:
load_hashers()
if algorithm not in HASHERS:
raise ValueError("Unknown password hashing algorithm '%s'. "
"Did you specify it in the PASSWORD_HASHERS "
"setting?" % algorithm)
return HASHERS[algorithm]
def mask_hash(hash, show=6, char="*"):
"""
Returns the given hash, with only the first ``show`` number shown. The
rest are masked with ``char`` for security reasons.
"""
masked = hash[:show]
masked += char * len(hash[show:])
return masked
class BasePasswordHasher(object):
"""
Abstract base class for password hashers
When creating your own hasher, you need to override algorithm,
verify(), encode() and safe_summary().
PasswordHasher objects are immutable.
"""
algorithm = None
library = None
def _load_library(self):
if self.library is not None:
if isinstance(self.library, (tuple, list)):
name, mod_path = self.library
else:
name = mod_path = self.library
try:
module = importlib.import_module(mod_path)
except ImportError:
raise ValueError("Couldn't load %s password algorithm "
"library" % name)
return module
raise ValueError("Hasher '%s' doesn't specify a library attribute" %
self.__class__)
def salt(self):
"""
Generates a cryptographically secure nonce salt in ascii
"""
return get_random_string()
def verify(self, password, encoded):
"""
Checks if the given password is correct
"""
raise NotImplementedError()
def encode(self, password, salt):
"""
Creates an encoded database value
The result is normally formatted as "algorithm$salt$hash" and
must be fewer than 128 characters.
"""
raise NotImplementedError()
def safe_summary(self, encoded):
"""
Returns a summary of safe values
The result is a dictionary and will be used where the password field
must be displayed to construct a safe representation of the password.
"""
raise NotImplementedError()
class PBKDF2PasswordHasher(BasePasswordHasher):
"""
Secure password hashing using the PBKDF2 algorithm (recommended)
Configured to use PBKDF2 + HMAC + SHA256 with 10000 iterations.
The result is a 64 byte binary string. Iterations may be changed
safely but you must rename the algorithm if you change SHA256.
"""
algorithm = "pbkdf2_sha256"
iterations = 10000
digest = hashlib.sha256
def encode(self, password, salt, iterations=None):
assert password
assert salt and '$' not in salt
if not iterations:
iterations = self.iterations
hash = pbkdf2(password, salt, iterations, digest=self.digest)
hash = hash.encode('base64').strip()
return "%s$%d$%s$%s" % (self.algorithm, iterations, salt, hash)
def verify(self, password, encoded):
algorithm, iterations, salt, hash = encoded.split('$', 3)
assert algorithm == self.algorithm
encoded_2 = self.encode(password, salt, int(iterations))
return constant_time_compare(encoded, encoded_2)
def safe_summary(self, encoded):
algorithm, iterations, salt, hash = encoded.split('$', 3)
assert algorithm == self.algorithm
return SortedDict([
(_('algorithm'), algorithm),
(_('iterations'), iterations),
(_('salt'), mask_hash(salt)),
(_('hash'), mask_hash(hash)),
])
class PBKDF2SHA1PasswordHasher(PBKDF2PasswordHasher):
"""
Alternate PBKDF2 hasher which uses SHA1, the default PRF
recommended by PKCS #5. This is compatible with other
implementations of PBKDF2, such as openssl's
PKCS5_PBKDF2_HMAC_SHA1().
"""
algorithm = "pbkdf2_sha1"
digest = hashlib.sha1
class BCryptPasswordHasher(BasePasswordHasher):
"""
Secure password hashing using the bcrypt algorithm (recommended)
This is considered by many to be the most secure algorithm but you
must first install the py-bcrypt library. Please be warned that
this library depends on native C code and might cause portability
issues.
"""
algorithm = "bcrypt"
library = ("py-bcrypt", "bcrypt")
rounds = 12
def salt(self):
bcrypt = self._load_library()
return bcrypt.gensalt(self.rounds)
def encode(self, password, salt):
bcrypt = self._load_library()
data = bcrypt.hashpw(password, salt)
return "%s$%s" % (self.algorithm, data)
def verify(self, password, encoded):
algorithm, data = encoded.split('$', 1)
assert algorithm == self.algorithm
bcrypt = self._load_library()
return constant_time_compare(data, bcrypt.hashpw(password, data))
def safe_summary(self, encoded):
algorithm, empty, algostr, work_factor, data = encoded.split('$', 4)
assert algorithm == self.algorithm
salt, checksum = data[:22], data[22:]
return SortedDict([
(_('algorithm'), algorithm),
(_('work factor'), work_factor),
(_('salt'), mask_hash(salt)),
(_('checksum'), mask_hash(checksum)),
])
class SHA1PasswordHasher(BasePasswordHasher):
"""
The SHA1 password hashing algorithm (not recommended)
"""
algorithm = "sha1"
def encode(self, password, salt):
assert password
assert salt and '$' not in salt
hash = hashlib.sha1(salt + password).hexdigest()
return "%s$%s$%s" % (self.algorithm, salt, hash)
def verify(self, password, encoded):
algorithm, salt, hash = encoded.split('$', 2)
assert algorithm == self.algorithm
encoded_2 = self.encode(password, salt)
return constant_time_compare(encoded, encoded_2)
def safe_summary(self, encoded):
algorithm, salt, hash = encoded.split('$', 2)
assert algorithm == self.algorithm
return SortedDict([
(_('algorithm'), algorithm),
(_('salt'), mask_hash(salt, show=2)),
(_('hash'), mask_hash(hash)),
])
class MD5PasswordHasher(BasePasswordHasher):
"""
The Salted MD5 password hashing algorithm (not recommended)
"""
algorithm = "md5"
def encode(self, password, salt):
assert password
assert salt and '$' not in salt
hash = hashlib.md5(salt + password).hexdigest()
return "%s$%s$%s" % (self.algorithm, salt, hash)
def verify(self, password, encoded):
algorithm, salt, hash = encoded.split('$', 2)
assert algorithm == self.algorithm
encoded_2 = self.encode(password, salt)
return constant_time_compare(encoded, encoded_2)
def safe_summary(self, encoded):
algorithm, salt, hash = encoded.split('$', 2)
assert algorithm == self.algorithm
return SortedDict([
(_('algorithm'), algorithm),
(_('salt'), mask_hash(salt, show=2)),
(_('hash'), mask_hash(hash)),
])
class UnsaltedMD5PasswordHasher(BasePasswordHasher):
"""
I am an incredibly insecure algorithm you should *never* use;
stores unsalted MD5 hashes without the algorithm prefix.
This class is implemented because Django used to store passwords
this way. Some older Django installs still have these values
lingering around so we need to handle and upgrade them properly.
"""
algorithm = "unsalted_md5"
def salt(self):
return ''
def encode(self, password, salt):
return hashlib.md5(password).hexdigest()
def verify(self, password, encoded):
encoded_2 = self.encode(password, '')
return constant_time_compare(encoded, encoded_2)
def safe_summary(self, encoded):
return SortedDict([
(_('algorithm'), self.algorithm),
(_('hash'), mask_hash(encoded, show=3)),
])
class CryptPasswordHasher(BasePasswordHasher):
"""
Password hashing using UNIX crypt (not recommended)
The crypt module is not supported on all platforms.
"""
algorithm = "crypt"
library = "crypt"
def salt(self):
return get_random_string(2)
def encode(self, password, salt):
crypt = self._load_library()
assert len(salt) == 2
data = crypt.crypt(password, salt)
# we don't need to store the salt, but Django used to do this
return "%s$%s$%s" % (self.algorithm, '', data)
def verify(self, password, encoded):
crypt = self._load_library()
algorithm, salt, data = encoded.split('$', 2)
assert algorithm == self.algorithm
return constant_time_compare(data, crypt.crypt(password, data))
def safe_summary(self, encoded):
algorithm, salt, data = encoded.split('$', 2)
assert algorithm == self.algorithm
return SortedDict([
(_('algorithm'), algorithm),
(_('salt'), salt),
(_('hash'), mask_hash(data, show=3)),
])
Something went wrong with that request. Please try again.