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# All Rights Reserved.
#
# 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.
"""
Secret utilities.
.. versionadded:: 3.5
"""
import hashlib
import hmac
def _constant_time_compare(first, second):
"""Return True if both string or binary inputs are equal, otherwise False.
This function should take a constant amount of time regardless of
how many characters in the strings match. This function uses an
approach designed to prevent timing analysis by avoiding
content-based short circuiting behaviour, making it appropriate
for cryptography.
"""
first = str(first)
second = str(second)
if len(first) != len(second):
return False
result = 0
for x, y in zip(first, second):
result |= ord(x) ^ ord(y)
return result == 0
try:
constant_time_compare = hmac.compare_digest
except AttributeError:
constant_time_compare = _constant_time_compare
try:
_ = hashlib.md5(usedforsecurity=False) # nosec
def md5(string=b'', usedforsecurity=True):
"""Return an md5 hashlib object using usedforsecurity parameter
For python distributions that support the usedforsecurity keyword
parameter, this passes the parameter through as expected.
See https://bugs.python.org/issue9216
"""
return hashlib.md5(string, usedforsecurity=usedforsecurity) # nosec
except TypeError:
def md5(string=b'', usedforsecurity=True):
"""Return an md5 hashlib object without usedforsecurity parameter
For python distributions that do not yet support this keyword
parameter, we drop the parameter
"""
return hashlib.md5(string) # nosec
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