diff --git a/src/aws_encryption_sdk/internal/crypto/authentication.py b/src/aws_encryption_sdk/internal/crypto/authentication.py
index 560fdb2a2..f90ac77e0 100644
--- a/src/aws_encryption_sdk/internal/crypto/authentication.py
+++ b/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 +46,9 @@ 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:
+        if not isinstance(self.algorithm.signing_algorithm_info, type(ec.EllipticCurve)):
             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.
diff --git a/src/aws_encryption_sdk/internal/crypto/elliptic_curve.py b/src/aws_encryption_sdk/internal/crypto/elliptic_curve.py
index 0febe7cc8..d2edde317 100644
--- a/src/aws_encryption_sdk/internal/crypto/elliptic_curve.py
+++ b/src/aws_encryption_sdk/internal/crypto/elliptic_curve.py
@@ -18,14 +18,13 @@
 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_to_bytes, verify_interface
+from cryptography.utils import int_to_bytes
 
 from ...exceptions import NotSupportedError
 from ..str_ops import to_bytes
 
 _LOGGER = logging.getLogger(__name__)
 
-
 # Curve parameter values are included strictly as a temporary measure
 #  until they can be rolled into the cryptography.io library.
 # Expanded values from http://www.secg.org/sec2-v2.pdf
@@ -44,10 +43,10 @@
         order=0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC7634D81F4372DDF581A0DB248B0A77AECEC196ACCC52973,
     ),
     "secp521r1": _ECCCurveParameters(
-        p=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,  # noqa pylint: disable=line-too-long
-        a=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC,  # noqa pylint: disable=line-too-long
-        b=0x0051953EB9618E1C9A1F929A21A0B68540EEA2DA725B99B315F3B8B489918EF109E156193951EC7E937B1652C0BD3BB1BF073573DF883D2C34F1EF451FD46B503F00,  # noqa pylint: disable=line-too-long
-        order=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409,  # noqa pylint: disable=line-too-long
+        p=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF, # noqa pylint: disable=line-too-long
+        a=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC, # noqa pylint: disable=line-too-long
+        b=0x0051953EB9618E1C9A1F929A21A0B68540EEA2DA725B99B315F3B8B489918EF109E156193951EC7E937B1652C0BD3BB1BF073573DF883D2C34F1EF451FD46B503F00, # noqa pylint: disable=line-too-long
+        order=0x01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409, # noqa pylint: disable=line-too-long
     ),
 }
 
@@ -182,8 +181,6 @@ 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:
+    if not isinstance(algorithm.signing_algorithm_info, type(ec.EllipticCurve)):
         raise NotSupportedError("Unsupported signing algorithm info")
+    return ec.generate_private_key(curve=algorithm.signing_algorithm_info(), backend=default_backend())
diff --git a/test/unit/test_crypto_authentication_signer.py b/test/unit/test_crypto_authentication_signer.py
index 440fa4f9b..11271abfb 100644
--- a/test/unit/test_crypto_authentication_signer.py
+++ b/test/unit/test_crypto_authentication_signer.py
@@ -30,6 +30,12 @@ def patch_default_backend(mocker):
     yield aws_encryption_sdk.internal.crypto.authentication.default_backend
 
 
+@pytest.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")
@@ -71,8 +77,10 @@ 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):
+    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 +91,11 @@ 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):
+    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()
 
@@ -98,13 +108,21 @@ 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)
+    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)
@@ -112,16 +130,19 @@ def test_signer_encoded_public_key(
     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):
+    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()
+    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)
diff --git a/test/unit/test_crypto_authentication_verifier.py b/test/unit/test_crypto_authentication_verifier.py
index b75d1c310..05af581eb 100644
--- a/test/unit/test_crypto_authentication_verifier.py
+++ b/test/unit/test_crypto_authentication_verifier.py
@@ -86,6 +86,7 @@ def test_f_verifier_key_bytes():
 def test_verifier_from_encoded_point(
     patch_default_backend,
     patch_serialization,
+    patch_ec,
     patch_ecc_public_numbers_from_compressed_point,
     patch_base64,
     patch_build_hasher,
@@ -94,21 +95,24 @@ def test_verifier_from_encoded_point(
     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()
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
 
-    verifier = Verifier.from_encoded_point(algorithm=algorithm, encoded_point=sentinel.encoded_point)
+    verifier = Verifier.from_encoded_point(algorithm=mock_algorithm, encoded_point=sentinel.encoded_point)
 
     patch_base64.b64decode.assert_called_once_with(sentinel.encoded_point)
-    algorithm.signing_algorithm_info.assert_called_once_with()
+    mock_algorithm.signing_algorithm_info.assert_called_once_with()
     patch_ecc_public_numbers_from_compressed_point.assert_called_once_with(
-        curve=algorithm.signing_algorithm_info.return_value, compressed_point=sentinel.compressed_point
+        curve=mock_algorithm.signing_algorithm_info.return_value, compressed_point=sentinel.compressed_point
     )
     mock_point_instance.public_key.assert_called_once_with(patch_default_backend.return_value)
     assert isinstance(verifier, Verifier)
 
 
-def test_verifier_update(patch_default_backend, patch_serialization, patch_build_hasher):
-    verifier = Verifier(algorithm=MagicMock(), key=MagicMock())
+def test_verifier_update(patch_default_backend, patch_serialization, patch_build_hasher, patch_ec):
+    mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info, spec=patch_ec.EllipticCurve)
+    mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
+    verifier = Verifier(algorithm=mock_algorithm, key=MagicMock())
     verifier.update(sentinel.data)
     verifier._hasher.update.assert_called_once_with(sentinel.data)
 
diff --git a/test/unit/test_crypto_elliptic_curve.py b/test/unit/test_crypto_elliptic_curve.py
index 445a28c79..02497b31c 100644
--- a/test/unit/test_crypto_elliptic_curve.py
+++ b/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
 
@@ -374,22 +373,20 @@ 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)
+    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
+def test_generate_ecc_signing_key_unsupported(patch_default_backend, patch_ec):
     mock_algorithm_info = MagicMock(return_value=sentinel.algorithm_info)
     mock_algorithm = MagicMock(signing_algorithm_info=mock_algorithm_info)
 
diff --git a/test/unit/test_crypto_prehashing_authenticator.py b/test/unit/test_crypto_prehashing_authenticator.py
index 158872f8c..104133da0 100644
--- a/test/unit/test_crypto_prehashing_authenticator.py
+++ b/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.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.fixture
 def patch_cryptography_ec(mocker):
     mocker.patch.object(aws_encryption_sdk.internal.crypto.authentication, "ec")
@@ -71,21 +64,18 @@ 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()
+    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
     with pytest.raises(NotSupportedError) as excinfo:
         _PrehashingAuthenticator(algorithm=MagicMock(), key=sentinel.key)
 
diff --git a/test_vector_handlers/src/pylintrc b/test_vector_handlers/src/pylintrc
index c78fe416a..dc5d95fff 100644
--- a/test_vector_handlers/src/pylintrc
+++ b/test_vector_handlers/src/pylintrc
@@ -1,4 +1,4 @@
-[MESSAGES CONTROL]
+[MESSAGE CONTROL]
 # Disabling messages that we either don't care about for tests or are necessary to break for tests.
 disable =
     bad-continuation,  # we let black handle this
diff --git a/test_vector_handlers/tox.ini b/test_vector_handlers/tox.ini
index 7418b2e98..10be9652d 100644
--- a/test_vector_handlers/tox.ini
+++ b/test_vector_handlers/tox.ini
@@ -105,12 +105,7 @@ commands =
 # Linters
 [testenv:flake8]
 basepython = python3
-deps =
-    ..
-    flake8
-    flake8-docstrings
-    # https://github.com/JBKahn/flake8-print/pull/30
-    flake8-print>=3.1.0
+deps = -r../dev_requirements/linter-requirements.txt
 commands =
     flake8 \
         src/awses_test_vectors/ \
@@ -120,25 +115,20 @@ commands =
 
 [testenv:flake8-tests]
 basepython = {[testenv:flake8]basepython}
-deps =
-    ..
-    flake8
+deps = -r../dev_requirements/linter-requirements.txt
 commands =
     flake8 \
         # Ignore F811 redefinition errors in tests (breaks with pytest-mock use)
         # E203 is not PEP8 compliant https://github.com/ambv/black#slices
         # W503 is not PEP8 compliant https://github.com/ambv/black#line-breaks--binary-operators
-        --ignore F811,E203,W503 \
-        test/ \
-        {posargs}
+        --ignore F811,E203,W503,D \
+        test/
 
 [testenv:pylint]
 basepython = python3
 deps =
     -rtest/requirements.txt
-    ..
-    pyflakes
-    pylint
+    -r../dev_requirements/linter-requirements.txt
 commands =
     pylint \
         --rcfile=src/pylintrc \
@@ -157,8 +147,7 @@ commands =
 
 [testenv:blacken-src]
 basepython = python3
-deps =
-    black
+deps = -r../dev_requirements/linter-requirements.txt
 commands =
     black --line-length 120 \
         src/awses_test_vectors/ \
@@ -184,14 +173,12 @@ commands =
 
 [testenv:isort-seed]
 basepython = python3
-deps = seed-isort-config
+deps = -r../dev_requirements/linter-requirements.txt
 commands = seed-isort-config
 
 [testenv:isort]
 basepython = python3
-deps = 
-    isort
-    ..
+deps = -r../dev_requirements/linter-requirements.txt
 commands = isort -rc \
     src \
     test \
@@ -216,29 +203,23 @@ commands =
 
 [testenv:doc8]
 basepython = python3
-deps =
-    sphinx
-    doc8
+deps = -r../dev_requirements/linter-requirements.txt
 commands = doc8 doc/index.rst README.rst CHANGELOG.rst
 
 [testenv:readme]
 basepython = python3
-deps =
-    ..
-    readme_renderer
+deps = -r../dev_requirements/linter-requirements.txt
 commands = python setup.py check -r -s
 
 [testenv:bandit]
 basepython = python3
-deps =
-    ..
-    bandit>=1.5.1
+deps = -r../dev_requirements/linter-requirements.txt
 commands = bandit -r src/awses_test_vectors/
 
 # Prone to false positives: only run independently
 [testenv:vulture]
 basepython = python3
-deps = vulture
+deps = -r../dev_requirements/linter-requirements.txt
 commands = vulture src/awses_test_vectors/
 
 [testenv:linters]
@@ -284,9 +265,7 @@ commands =
 [testenv:park]
 basepython = python3
 skip_install = true
-deps =
-    pypi-parker
-    setuptools
+deps = -r../dev_requirements/release-requirements.txt
 commands = python setup.py park
 
 [testenv:build]
@@ -294,8 +273,7 @@ basepython = python3
 skip_install = true
 deps =
     {[testenv:docs]deps}
-    wheel
-    setuptools
+    -r../dev_requirements/release-requirements.txt
 commands =
     {[testenv:docs]commands}
     python setup.py sdist bdist_wheel