tests/hazmat/backends/test_commoncrypto.py

# 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
#
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# distributed under the License is distributed on an "AS IS" BASIS,
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# 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 utils
from cryptography.exceptions import InternalError, _Reasons
from cryptography.hazmat.bindings.commoncrypto.binding import Binding
from cryptography.hazmat.primitives import interfaces
from cryptography.hazmat.primitives.ciphers.algorithms import AES
from cryptography.hazmat.primitives.ciphers.base import Cipher
from cryptography.hazmat.primitives.ciphers.modes import CBC, GCM

from ...utils import raises_unsupported_algorithm


@utils.register_interface(interfaces.CipherAlgorithm)
class DummyCipher(object):
    name = "dummy-cipher"
    block_size = 128


@pytest.mark.skipif(not Binding.is_available(),
                    reason="CommonCrypto not available")
class TestCommonCrypto(object):
    def test_supports_cipher(self):
        from cryptography.hazmat.backends.commoncrypto.backend import backend
        assert backend.cipher_supported(None, None) is False

    def test_register_duplicate_cipher_adapter(self):
        from cryptography.hazmat.backends.commoncrypto.backend import backend
        with pytest.raises(ValueError):
            backend._register_cipher_adapter(
                AES, backend._lib.kCCAlgorithmAES128,
                CBC, backend._lib.kCCModeCBC
            )

    def test_handle_response(self):
        from cryptography.hazmat.backends.commoncrypto.backend import backend

        with pytest.raises(ValueError):
            backend._check_response(backend._lib.kCCAlignmentError)

        with pytest.raises(InternalError):
            backend._check_response(backend._lib.kCCMemoryFailure)

        with pytest.raises(InternalError):
            backend._check_response(backend._lib.kCCDecodeError)

    def test_nonexistent_aead_cipher(self):
        from cryptography.hazmat.backends.commoncrypto.backend import Backend
        b = Backend()
        cipher = Cipher(
            DummyCipher(), GCM(b"fake_iv_here"), backend=b,
        )
        with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_CIPHER):
            cipher.encryptor()