mirror of
https://github.com/PiBrewing/craftbeerpi4.git
synced 2024-12-02 03:34:22 +01:00
74 lines
2.4 KiB
Python
74 lines
2.4 KiB
Python
# This file is dual licensed under the terms of the Apache License, Version
|
|
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
|
|
# for complete details.
|
|
|
|
from __future__ import absolute_import, division, print_function
|
|
|
|
import struct
|
|
|
|
from cryptography import utils
|
|
from cryptography.exceptions import (
|
|
AlreadyFinalized,
|
|
InvalidKey,
|
|
UnsupportedAlgorithm,
|
|
_Reasons,
|
|
)
|
|
from cryptography.hazmat.backends import _get_backend
|
|
from cryptography.hazmat.backends.interfaces import HashBackend
|
|
from cryptography.hazmat.primitives import constant_time, hashes
|
|
from cryptography.hazmat.primitives.kdf import KeyDerivationFunction
|
|
|
|
|
|
def _int_to_u32be(n):
|
|
return struct.pack(">I", n)
|
|
|
|
|
|
@utils.register_interface(KeyDerivationFunction)
|
|
class X963KDF(object):
|
|
def __init__(self, algorithm, length, sharedinfo, backend=None):
|
|
backend = _get_backend(backend)
|
|
|
|
max_len = algorithm.digest_size * (2 ** 32 - 1)
|
|
if length > max_len:
|
|
raise ValueError(
|
|
"Can not derive keys larger than {} bits.".format(max_len)
|
|
)
|
|
if sharedinfo is not None:
|
|
utils._check_bytes("sharedinfo", sharedinfo)
|
|
|
|
self._algorithm = algorithm
|
|
self._length = length
|
|
self._sharedinfo = sharedinfo
|
|
|
|
if not isinstance(backend, HashBackend):
|
|
raise UnsupportedAlgorithm(
|
|
"Backend object does not implement HashBackend.",
|
|
_Reasons.BACKEND_MISSING_INTERFACE,
|
|
)
|
|
self._backend = backend
|
|
self._used = False
|
|
|
|
def derive(self, key_material):
|
|
if self._used:
|
|
raise AlreadyFinalized
|
|
self._used = True
|
|
utils._check_byteslike("key_material", key_material)
|
|
output = [b""]
|
|
outlen = 0
|
|
counter = 1
|
|
|
|
while self._length > outlen:
|
|
h = hashes.Hash(self._algorithm, self._backend)
|
|
h.update(key_material)
|
|
h.update(_int_to_u32be(counter))
|
|
if self._sharedinfo is not None:
|
|
h.update(self._sharedinfo)
|
|
output.append(h.finalize())
|
|
outlen += len(output[-1])
|
|
counter += 1
|
|
|
|
return b"".join(output)[: self._length]
|
|
|
|
def verify(self, key_material, expected_key):
|
|
if not constant_time.bytes_eq(self.derive(key_material), expected_key):
|
|
raise InvalidKey
|