refactor: change verify_interface to isinstance

Author: josecorella

requirements.txt

@@ -1,4 +1,4 @@
 boto3>=1.10.0
-cryptography>=2.5.0
+cryptography>=2.5.0,<3.3.2
 attrs>=17.4.0
 wrapt>=1.10.11

src/aws_encryption_sdk/internal/crypto/authentication.py

@@ -18,7 +18,6 @@
 from cryptography.hazmat.primitives import hashes, serialization
 from cryptography.hazmat.primitives.asymmetric import ec
 from cryptography.hazmat.primitives.asymmetric.utils import Prehashed
-from cryptography.utils import InterfaceNotImplemented, verify_interface
 
 from ...exceptions import NotSupportedError
 from .elliptic_curve import (
@@ -47,11 +46,10 @@ def __init__(self, algorithm, key):
 
     def _set_signature_type(self):
         """Ensures that the algorithm signature type is a known type and sets a reference value."""
-        try:
-            verify_interface(ec.EllipticCurve, self.algorithm.signing_algorithm_info)
-            return ec.EllipticCurve
-        except InterfaceNotImplemented:
-            raise NotSupportedError("Unsupported signing algorithm info")
+        for method in ec.EllipticCurve.__abstractmethods__:
+            if not hasattr(self.algorithm.signing_algorithm_info(), method):
+                raise NotSupportedError("Unsupported signing algorithm info")
+        return ec.EllipticCurve
 
     def _build_hasher(self):
         """Builds the hasher instance which will calculate the digest of all passed data.

src/aws_encryption_sdk/internal/crypto/elliptic_curve.py

@@ -18,7 +18,7 @@
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives.asymmetric import ec
 from cryptography.hazmat.primitives.asymmetric.utils import Prehashed, decode_dss_signature, encode_dss_signature
-from cryptography.utils import InterfaceNotImplemented, int_from_bytes, int_to_bytes, verify_interface
+from cryptography.utils import int_from_bytes, int_to_bytes
 
 from ...exceptions import NotSupportedError
 from ..str_ops import to_bytes
@@ -183,8 +183,7 @@ def generate_ecc_signing_key(algorithm):
     :returns: Generated signing key
     :raises NotSupportedError: if signing algorithm is not supported on this platform
     """
-    try:
-        verify_interface(ec.EllipticCurve, algorithm.signing_algorithm_info)
-        return ec.generate_private_key(curve=algorithm.signing_algorithm_info(), backend=default_backend())
-    except InterfaceNotImplemented:
-        raise NotSupportedError("Unsupported signing algorithm info")
+    for method in ec.EllipticCurve.__abstractmethods__:
+        if not hasattr(algorithm.signing_algorithm_info(), method):
+            raise NotSupportedError("Unsupported signing algorithm info")
+    return ec.generate_private_key(curve=algorithm.signing_algorithm_info(), backend=default_backend())

test/unit/test_crypto_authentication_signer.py

@@ -1,18 +1,6 @@
-# Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License"). You
-# may not use this file except in compliance with the License. A copy of
-# the License is located at
-#
-# http://aws.amazon.com/apache2.0/
-#
-# or in the "license" file accompanying this file. This file 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.
 """Unit test suite for ``aws_encryption_sdk.internal.crypto.authentication.Signer``."""
 import pytest
-from mock import MagicMock, sentinel
+from mock import MagicMock, sentinel, patch
 from pytest_mock import mocker  # noqa pylint: disable=unused-import
 
 import aws_encryption_sdk.internal.crypto.authentication
@@ -31,6 +19,12 @@ def patch_default_backend(mocker):
 
 
 @pytest.yield_fixture
+def patch_ec(mocker):
+    mocker.patch.object(aws_encryption_sdk.internal.crypto.authentication, "ec")
+    yield aws_encryption_sdk.internal.crypto.authentication.ec
+
+
+@pytest.fixture
 def patch_serialization(mocker):
     mocker.patch.object(aws_encryption_sdk.internal.crypto.authentication, "serialization")
     yield aws_encryption_sdk.internal.crypto.authentication.serialization
@@ -71,8 +65,11 @@ def test_f_signer_key_bytes():
     assert test.key_bytes() == VALUES["ecc_private_key_prime_private_bytes"]
 
 
-def test_signer_from_key_bytes(patch_default_backend, patch_serialization, patch_build_hasher):
-    _algorithm = MagicMock()
+def test_signer_from_key_bytes(patch_default_backend, patch_serialization, patch_build_hasher, patch_ec):
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    _algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
+
     signer = Signer.from_key_bytes(algorithm=_algorithm, key_bytes=sentinel.key_bytes)
 
     patch_serialization.load_der_private_key.assert_called_once_with(
@@ -83,9 +80,12 @@ def test_signer_from_key_bytes(patch_default_backend, patch_serialization, patch
     assert signer.key is patch_serialization.load_der_private_key.return_value
 
 
-def test_signer_key_bytes(patch_default_backend, patch_serialization, patch_build_hasher):
+def test_signer_key_bytes(patch_default_backend, patch_serialization, patch_build_hasher, patch_ec):
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
     private_key = MagicMock()
-    signer = Signer(MagicMock(), key=private_key)
+    signer = Signer(algorithm, key=private_key)
 
     test = signer.key_bytes()
 
@@ -98,30 +98,45 @@ def test_signer_key_bytes(patch_default_backend, patch_serialization, patch_buil
 
 
 def test_signer_encoded_public_key(
-    patch_default_backend, patch_serialization, patch_build_hasher, patch_ecc_encode_compressed_point, patch_base64
+    patch_default_backend,
+    patch_serialization,
+    patch_build_hasher,
+    patch_ecc_encode_compressed_point,
+    patch_base64,
+    patch_ec
 ):
     patch_ecc_encode_compressed_point.return_value = sentinel.compressed_point
     patch_base64.b64encode.return_value = sentinel.encoded_point
     private_key = MagicMock()
 
-    signer = Signer(MagicMock(), key=private_key)
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
+
+    signer = Signer(algorithm, key=private_key)
     test_key = signer.encoded_public_key()
 
     patch_ecc_encode_compressed_point.assert_called_once_with(private_key)
     patch_base64.b64encode.assert_called_once_with(sentinel.compressed_point)
     assert test_key == sentinel.encoded_point
 
 
-def test_signer_update(patch_default_backend, patch_serialization, patch_build_hasher):
-    signer = Signer(MagicMock(), key=MagicMock())
+def test_signer_update(patch_default_backend, patch_serialization, patch_build_hasher, patch_ec):
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
+    signer = Signer(algorithm, key=MagicMock())
     signer.update(sentinel.data)
     patch_build_hasher.return_value.update.assert_called_once_with(sentinel.data)
 
 
 def test_signer_finalize(
-    patch_default_backend, patch_serialization, patch_build_hasher, patch_ecc_static_length_signature
+    patch_default_backend, patch_serialization, patch_build_hasher, patch_ecc_static_length_signature, patch_ec
 ):
-    algorithm = MagicMock()
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
     private_key = MagicMock()
 
     signer = Signer(algorithm, key=private_key)

test/unit/test_crypto_authentication_verifier.py

@@ -18,6 +18,7 @@
 import aws_encryption_sdk.internal.crypto.authentication
 from aws_encryption_sdk.internal.crypto.authentication import Verifier
 from aws_encryption_sdk.internal.defaults import ALGORITHM
+from cryptography.hazmat.primitives.asymmetric import ec
 
 from .test_crypto import VALUES
 
@@ -89,12 +90,16 @@ def test_verifier_from_encoded_point(
     patch_ecc_public_numbers_from_compressed_point,
     patch_base64,
     patch_build_hasher,
+    patch_ec
 ):
     mock_point_instance = MagicMock()
     mock_point_instance.public_key.return_value = sentinel.public_key
     patch_ecc_public_numbers_from_compressed_point.return_value = mock_point_instance
     patch_base64.b64decode.return_value = sentinel.compressed_point
-    algorithm = MagicMock()
+
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
 
     verifier = Verifier.from_encoded_point(algorithm=algorithm, encoded_point=sentinel.encoded_point)
 

test/unit/test_crypto_elliptic_curve.py

@@ -15,7 +15,6 @@
 
 import pytest
 from cryptography.hazmat.primitives.asymmetric import ec
-from cryptography.utils import InterfaceNotImplemented
 from mock import MagicMock, sentinel
 from pytest_mock import mocker  # noqa pylint: disable=unused-import
 
@@ -72,12 +71,6 @@ def patch_ecc_decode_compressed_point(mocker):
     yield aws_encryption_sdk.internal.crypto.elliptic_curve._ecc_decode_compressed_point
 
 
-@pytest.yield_fixture
-def patch_verify_interface(mocker):
-    mocker.patch.object(aws_encryption_sdk.internal.crypto.elliptic_curve, "verify_interface")
-    yield aws_encryption_sdk.internal.crypto.elliptic_curve.verify_interface
-
-
 @pytest.yield_fixture
 def patch_ecc_curve_parameters(mocker):
     mocker.patch.object(aws_encryption_sdk.internal.crypto.elliptic_curve, "_ECC_CURVE_PARAMETERS")
@@ -374,23 +367,24 @@ def test_ecc_public_numbers_from_compressed_point(patch_ec, patch_ecc_decode_com
     assert test == sentinel.public_numbers_instance
 
 
-def test_generate_ecc_signing_key_supported(patch_default_backend, patch_ec, patch_verify_interface):
+def test_generate_ecc_signing_key_supported(patch_default_backend, patch_ec):
     patch_ec.generate_private_key.return_value = sentinel.raw_signing_key
-    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info)
+    patch_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
     mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
 
     test_signing_key = generate_ecc_signing_key(algorithm=mock_algorithm)
 
-    patch_verify_interface.assert_called_once_with(patch_ec.EllipticCurve, mock_algorithm_info)
     patch_ec.generate_private_key.assert_called_once_with(
         curve=sentinel.algorithm_info, backend=patch_default_backend.return_value
     )
     assert test_signing_key is sentinel.raw_signing_key
 
 
-def test_generate_ecc_signing_key_unsupported(patch_default_backend, patch_ec, patch_verify_interface):
-    patch_verify_interface.side_effect = InterfaceNotImplemented
-    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info)
+def test_generate_ecc_signing_key_unsupported(patch_default_backend, patch_ec):
+    patch_ec.generate_private_key.return_value = sentinel.raw_signing_key
+    patch_ec.EllipticCurve.__abstractmethods__ = set("notName")
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
     mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
 
     with pytest.raises(NotSupportedError) as excinfo:

test/unit/test_crypto_prehashing_authenticator.py

@@ -12,7 +12,6 @@
 # language governing permissions and limitations under the License.
 """Unit test suite for ``aws_encryption_sdk.internal.crypto._PrehashingAuthenticater``."""
 import pytest
-from cryptography.utils import InterfaceNotImplemented
 from mock import MagicMock, sentinel
 from pytest_mock import mocker  # noqa pylint: disable=unused-import
 
@@ -35,12 +34,6 @@ def patch_build_hasher(mocker):
     yield _PrehashingAuthenticator._build_hasher
 
 
-@pytest.yield_fixture
-def patch_cryptography_utils_verify_interface(mocker):
-    mocker.patch.object(aws_encryption_sdk.internal.crypto.authentication, "verify_interface")
-    yield aws_encryption_sdk.internal.crypto.authentication.verify_interface
-
-
 @pytest.yield_fixture
 def patch_cryptography_ec(mocker):
     mocker.patch.object(aws_encryption_sdk.internal.crypto.authentication, "ec")
@@ -71,23 +64,25 @@ def test_init(patch_set_signature_type, patch_build_hasher):
 
 
 def test_set_signature_type_elliptic_curve(
-    patch_build_hasher, patch_cryptography_utils_verify_interface, patch_cryptography_ec
+    patch_build_hasher, patch_cryptography_ec
 ):
-    mock_algorithm = MagicMock()
+    patch_cryptography_ec.generate_private_key.return_value = sentinel.raw_signing_key
+    patch_cryptography_ec.EllipticCurve.__abstractmethods__ = set()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_cryptography_ec.EllipticCurve)
+    mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
     test = _PrehashingAuthenticator(algorithm=mock_algorithm, key=sentinel.key)
 
-    patch_cryptography_utils_verify_interface.assert_called_once_with(
-        patch_cryptography_ec.EllipticCurve, mock_algorithm.signing_algorithm_info
-    )
     assert test._signature_type is patch_cryptography_ec.EllipticCurve
 
 
 def test_set_signature_type_unknown(
-    patch_build_hasher, patch_cryptography_utils_verify_interface, patch_cryptography_ec
+    patch_build_hasher, patch_cryptography_ec
 ):
-    patch_cryptography_utils_verify_interface.side_effect = InterfaceNotImplemented
+    patch_cryptography_ec.EllipticCurve.__abstractmethods__ = set("invalidSetup")
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_cryptography_ec.EllipticCurve)
+    mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
     with pytest.raises(NotSupportedError) as excinfo:
-        _PrehashingAuthenticator(algorithm=MagicMock(), key=sentinel.key)
+        _PrehashingAuthenticator(algorithm=mock_algorithm, key=sentinel.key)
 
     excinfo.match(r"Unsupported signing algorithm info")