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
|
# 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, division, print_function
from cryptography.exceptions import InvalidKey, UnsupportedAlgorithm
from cryptography.hazmat.primitives import constant_time
class PBKDF2(object):
def __init__(self, algorithm, length, salt, iterations, backend):
if not backend.pbkdf2_hash_supported(algorithm):
raise UnsupportedAlgorithm(
"{0} is not supported by this backend".format(algorithm.name)
)
self.algorithm = algorithm
if length > 2**31 - 1:
raise ValueError("Requested length too large.")
self._length = length
# TODO: handle salt
self._salt = salt
self.iterations = iterations
self._backend = backend
def derive(self, key_material):
return self._backend.derive_pbkdf2(
self.algorithm,
self._length,
self._salt,
self.iterations,
key_material
)
def verify(self, key_material, expected_key):
if not constant_time.bytes_eq(key_material, expected_key):
raise InvalidKey("Signature did not match digest.")
|
