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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 binascii
import pytest
from cryptography import utils
from cryptography.exceptions import (
UnsupportedAlgorithm, AlreadyFinalized,
)
from cryptography.hazmat.primitives import interfaces
from cryptography.hazmat.primitives.ciphers import (
Cipher, algorithms, modes
)
from .utils import (
generate_aead_exception_test, generate_aead_tag_exception_test
)
@utils.register_interface(interfaces.Mode)
class DummyMode(object):
name = "dummy-mode"
@utils.register_interface(interfaces.CipherAlgorithm)
class DummyCipher(object):
name = "dummy-cipher"
@pytest.mark.cipher
class TestCipher(object):
def test_creates_encryptor(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
assert isinstance(cipher.encryptor(), interfaces.CipherContext)
def test_creates_decryptor(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
assert isinstance(cipher.decryptor(), interfaces.CipherContext)
def test_instantiate_with_non_algorithm(self, backend):
algorithm = object()
with pytest.raises(TypeError):
Cipher(algorithm, mode=None, backend=backend)
@pytest.mark.cipher
class TestCipherContext(object):
def test_use_after_finalize(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
encryptor = cipher.encryptor()
encryptor.update(b"a" * 16)
encryptor.finalize()
with pytest.raises(AlreadyFinalized):
encryptor.update(b"b" * 16)
with pytest.raises(AlreadyFinalized):
encryptor.finalize()
decryptor = cipher.decryptor()
decryptor.update(b"a" * 16)
decryptor.finalize()
with pytest.raises(AlreadyFinalized):
decryptor.update(b"b" * 16)
with pytest.raises(AlreadyFinalized):
decryptor.finalize()
def test_unaligned_block_encryption(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.ECB(),
backend
)
encryptor = cipher.encryptor()
ct = encryptor.update(b"a" * 15)
assert ct == b""
ct += encryptor.update(b"a" * 65)
assert len(ct) == 80
ct += encryptor.finalize()
decryptor = cipher.decryptor()
pt = decryptor.update(ct[:3])
assert pt == b""
pt += decryptor.update(ct[3:])
assert len(pt) == 80
assert pt == b"a" * 80
decryptor.finalize()
@pytest.mark.parametrize("mode", [DummyMode(), None])
def test_nonexistent_cipher(self, backend, mode):
cipher = Cipher(
DummyCipher(), mode, backend
)
with pytest.raises(UnsupportedAlgorithm):
cipher.encryptor()
with pytest.raises(UnsupportedAlgorithm):
cipher.decryptor()
def test_incorrectly_padded(self, backend):
cipher = Cipher(
algorithms.AES(b"\x00" * 16),
modes.CBC(b"\x00" * 16),
backend
)
encryptor = cipher.encryptor()
encryptor.update(b"1")
with pytest.raises(ValueError):
encryptor.finalize()
decryptor = cipher.decryptor()
decryptor.update(b"1")
with pytest.raises(ValueError):
decryptor.finalize()
@pytest.mark.cipher
class TestAEADCipherContext(object):
test_aead_exceptions = generate_aead_exception_test(
algorithms.AES,
modes.GCM,
only_if=lambda backend: backend.cipher_supported(
algorithms.AES("\x00" * 16), modes.GCM("\x00" * 12)
),
skip_message="Does not support AES GCM",
)
test_aead_tag_exceptions = generate_aead_tag_exception_test(
algorithms.AES,
modes.GCM,
only_if=lambda backend: backend.cipher_supported(
algorithms.AES("\x00" * 16), modes.GCM("\x00" * 12)
),
skip_message="Does not support AES GCM",
)
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