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# Author:: Donald Stufft (<donald@stufft.io>)
# Copyright:: Copyright (c) 2013 Donald Stufft
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import
from __future__ import division
import os
import re
import warnings
import six
from . import _bcrypt # type: ignore
from .__about__ import (
__author__,
__copyright__,
__email__,
__license__,
__summary__,
__title__,
__uri__,
__version__,
)
__all__ = [
"__title__",
"__summary__",
"__uri__",
"__version__",
"__author__",
"__email__",
"__license__",
"__copyright__",
"gensalt",
"hashpw",
"kdf",
"checkpw",
]
_normalize_re = re.compile(br"^\$2y\$")
def gensalt(rounds: int = 12, prefix: bytes = b"2b") -> bytes:
if prefix not in (b"2a", b"2b"):
raise ValueError("Supported prefixes are b'2a' or b'2b'")
if rounds < 4 or rounds > 31:
raise ValueError("Invalid rounds")
salt = os.urandom(16)
output = _bcrypt.ffi.new("char[]", 30)
_bcrypt.lib.encode_base64(output, salt, len(salt))
return (
b"$"
+ prefix
+ b"$"
+ ("%2.2u" % rounds).encode("ascii")
+ b"$"
+ _bcrypt.ffi.string(output)
)
def hashpw(password: bytes, salt: bytes) -> bytes:
if isinstance(password, six.text_type) or isinstance(salt, six.text_type):
raise TypeError("Unicode-objects must be encoded before hashing")
if b"\x00" in password:
raise ValueError("password may not contain NUL bytes")
# bcrypt originally suffered from a wraparound bug:
# http://www.openwall.com/lists/oss-security/2012/01/02/4
# This bug was corrected in the OpenBSD source by truncating inputs to 72
# bytes on the updated prefix $2b$, but leaving $2a$ unchanged for
# compatibility. However, pyca/bcrypt 2.0.0 *did* correctly truncate inputs
# on $2a$, so we do it here to preserve compatibility with 2.0.0
password = password[:72]
# When the original 8bit bug was found the original library we supported
# added a new prefix, $2y$, that fixes it. This prefix is exactly the same
# as the $2b$ prefix added by OpenBSD other than the name. Since the
# OpenBSD library does not support the $2y$ prefix, if the salt given to us
# is for the $2y$ prefix, we'll just mugne it so that it's a $2b$ prior to
# passing it into the C library.
original_salt, salt = salt, _normalize_re.sub(b"$2b$", salt)
hashed = _bcrypt.ffi.new("char[]", 128)
retval = _bcrypt.lib.bcrypt_hashpass(password, salt, hashed, len(hashed))
if retval != 0:
raise ValueError("Invalid salt")
# Now that we've gotten our hashed password, we want to ensure that the
# prefix we return is the one that was passed in, so we'll use the prefix
# from the original salt and concatenate that with the return value (minus
# the return value's prefix). This will ensure that if someone passed in a
# salt with a $2y$ prefix, that they get back a hash with a $2y$ prefix
# even though we munged it to $2b$.
return original_salt[:4] + _bcrypt.ffi.string(hashed)[4:]
def checkpw(password: bytes, hashed_password: bytes) -> bool:
if isinstance(password, six.text_type) or isinstance(
hashed_password, six.text_type
):
raise TypeError("Unicode-objects must be encoded before checking")
if b"\x00" in password or b"\x00" in hashed_password:
raise ValueError(
"password and hashed_password may not contain NUL bytes"
)
ret = hashpw(password, hashed_password)
if len(ret) != len(hashed_password):
return False
return _bcrypt.lib.timingsafe_bcmp(ret, hashed_password, len(ret)) == 0
def kdf(
password: bytes,
salt: bytes,
desired_key_bytes: int,
rounds: int,
ignore_few_rounds: bool = False,
) -> bytes:
if isinstance(password, six.text_type) or isinstance(salt, six.text_type):
raise TypeError("Unicode-objects must be encoded before hashing")
if len(password) == 0 or len(salt) == 0:
raise ValueError("password and salt must not be empty")
if desired_key_bytes <= 0 or desired_key_bytes > 512:
raise ValueError("desired_key_bytes must be 1-512")
if rounds < 1:
raise ValueError("rounds must be 1 or more")
if rounds < 50 and not ignore_few_rounds:
# They probably think bcrypt.kdf()'s rounds parameter is logarithmic,
# expecting this value to be slow enough (it probably would be if this
# were bcrypt). Emit a warning.
warnings.warn(
(
"Warning: bcrypt.kdf() called with only {0} round(s). "
"This few is not secure: the parameter is linear, like PBKDF2."
).format(rounds),
UserWarning,
stacklevel=2,
)
key = _bcrypt.ffi.new("uint8_t[]", desired_key_bytes)
res = _bcrypt.lib.bcrypt_pbkdf(
password, len(password), salt, len(salt), key, len(key), rounds
)
_bcrypt_assert(res == 0)
return _bcrypt.ffi.buffer(key, desired_key_bytes)[:]
def _bcrypt_assert(ok: bool) -> None:
if not ok:
raise SystemError("bcrypt assertion failed")
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