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# 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
import pytest
from cryptography import exceptions
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
@pytest.mark.hash
class TestHKDF(object):
def test_length_limit(self, backend):
big_length = 255 * (hashes.SHA256().digest_size // 8) + 1
with pytest.raises(ValueError):
HKDF(
hashes.SHA256(),
big_length,
salt=None,
info=None,
backend=backend
)
def test_already_finalized(self, backend):
hkdf = HKDF(
hashes.SHA256(),
16,
salt=None,
info=None,
backend=backend
)
hkdf.derive('\x01' * 16)
with pytest.raises(exceptions.AlreadyFinalized):
hkdf.derive('\x02' * 16)
hkdf = HKDF(
hashes.SHA256(),
16,
salt=None,
info=None,
backend=backend
)
hkdf.verify('\x01' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
with pytest.raises(exceptions.AlreadyFinalized):
hkdf.verify('\x02' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
def test_verify(self, backend):
hkdf = HKDF(
hashes.SHA256(),
16,
salt=None,
info=None,
backend=backend
)
hkdf.verify('\x01' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
def test_verify_invalid(self, backend):
hkdf = HKDF(
hashes.SHA256(),
16,
salt=None,
info=None,
backend=backend
)
with pytest.raises(exceptions.InvalidKey):
hkdf.verify('\x02' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
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