add minimum key size checks and warnings

.travis.yml

@@ -4,33 +4,33 @@ matrix:
   include:
     # CPython 2.7
     - python: 2.7
-      env: TOXENV=py27-local-slow
+      env: TOXENV=py27-local-fast
     - python: 2.7
-      env: TOXENV=py27-integ-slow
+      env: TOXENV=py27-integ-fast
     # CPython 3.4
     - python: 3.4
-      env: TOXENV=py34-local-slow
+      env: TOXENV=py34-local-fast
     - python: 3.4
-      env: TOXENV=py34-integ-slow
+      env: TOXENV=py34-integ-fast
     # CPython 3.5
     - python: 3.5
-      env: TOXENV=py35-local-slow
+      env: TOXENV=py35-local-fast
     - python: 3.5
-      env: TOXENV=py35-integ-slow
+      env: TOXENV=py35-integ-fast
     # CPython 3.6
     - python: 3.6
-      env: TOXENV=py36-local-slow
+      env: TOXENV=py36-local-fast
     - python: 3.6
-      env: TOXENV=py36-integ-slow
+      env: TOXENV=py36-integ-fast
     # CPython 3.7
     # xenial + sudo are currently needed to get 3.7
     # https://github.com/travis-ci/travis-ci/issues/9815
     - python: 3.7
-      env: TOXENV=py37-local-slow
+      env: TOXENV=py37-local-fast
       dist: xenial
       sudo: true
     - python: 3.7
-      env: TOXENV=py37-integ-slow
+      env: TOXENV=py37-integ-fast
       dist: xenial
       sudo: true
     # Upstream tests

examples/__init__.py

@@ -0,0 +1,13 @@
+# Copyright 2018 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.
+"""Stub to allow relative imports of examples from tests."""

examples/test/examples_test_utils.py

@@ -0,0 +1,10 @@
+"""
+Helper utilities for use while testing examples.
+"""
+import os
+import sys
+
+os.environ["AWS_ENCRYPTION_SDK_EXAMPLES_TESTING"] = "yes"
+sys.path.extend([os.sep.join([os.path.dirname(__file__), "..", "..", "test", "integration"])])
+
+from integration_test_utils import cmk_arn, ddb_table_name  # noqa pylint: disable=unused-import

examples/test/test_aws_kms_encrypted_examples.py

@@ -11,23 +11,10 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Test ``aws_kms_encrypted_*`` examples."""
-import os
-import sys
-
-sys.path.extend(
-    [  # noqa
-        os.sep.join([os.path.dirname(__file__), "..", "..", "test", "integration"]),
-        os.sep.join([os.path.dirname(__file__), "..", "src"]),
-    ]
-)
-
 import pytest
 
-import aws_kms_encrypted_client  # noqa
-import aws_kms_encrypted_item  # noqa
-import aws_kms_encrypted_resource  # noqa
-import aws_kms_encrypted_table  # noqa
-from integration_test_utils import cmk_arn, ddb_table_name  # noqa pylint: disable=unused-import
+from ..src import aws_kms_encrypted_client, aws_kms_encrypted_item, aws_kms_encrypted_resource, aws_kms_encrypted_table
+from .examples_test_utils import cmk_arn, ddb_table_name  # noqa pylint: disable=unused-import
 
 pytestmark = [pytest.mark.examples]
 

examples/test/test_most_recent_provider_encrypted_examples.py

@@ -11,23 +11,15 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Test most recent provider examples."""
-import os
-import sys
-
-sys.path.extend(
-    [  # noqa
-        os.sep.join([os.path.dirname(__file__), "..", "..", "test", "integration"]),
-        os.sep.join([os.path.dirname(__file__), "..", "src"]),
-    ]
-)
 import uuid
 
 import boto3
 import pytest
 
 from dynamodb_encryption_sdk.material_providers.store.meta import MetaStore
-import most_recent_provider_encrypted_table  # noqa
-from integration_test_utils import cmk_arn, ddb_table_name  # noqa pylint: disable=unused-import
+
+from ..src import most_recent_provider_encrypted_table
+from .examples_test_utils import cmk_arn, ddb_table_name  # noqa pylint: disable=unused-import
 
 pytestmark = [pytest.mark.examples]
 

examples/test/test_wrapped_encrypted_examples.py

@@ -11,22 +11,12 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Test ``wrapped_*_encrypted_*`` examples."""
-import os
-import sys
-
-sys.path.extend(
-    [  # noqa
-        os.sep.join([os.path.dirname(__file__), "..", "..", "test", "integration"]),
-        os.sep.join([os.path.dirname(__file__), "..", "src"]),
-    ]
-)
-
 import pytest
 
 from dynamodb_encryption_sdk.delegated_keys.jce import JceNameLocalDelegatedKey
-import wrapped_rsa_encrypted_table  # noqa
-import wrapped_symmetric_encrypted_table  # noqa
-from integration_test_utils import ddb_table_name  # noqa pylint: disable=unused-import
+
+from ..src import wrapped_rsa_encrypted_table, wrapped_symmetric_encrypted_table
+from .examples_test_utils import ddb_table_name  # noqa pylint: disable=unused-import
 
 pytestmark = [pytest.mark.examples]
 

src/dynamodb_encryption_sdk/internal/crypto/jce_bridge/authentication.py

@@ -27,6 +27,7 @@
 
 from dynamodb_encryption_sdk.exceptions import InvalidAlgorithmError, SignatureVerificationError, SigningError
 from dynamodb_encryption_sdk.identifiers import LOGGER_NAME, EncryptionKeyType, KeyEncodingType
+from dynamodb_encryption_sdk.internal.identifiers import MinimumKeySizes
 from dynamodb_encryption_sdk.internal.validators import callable_validator
 
 from .primitives import load_rsa_key
@@ -37,7 +38,6 @@
     # We only actually need these imports when running the mypy checks
     pass
 
-
 __all__ = ("JavaAuthenticator", "JavaMac", "JavaSignature", "JAVA_AUTHENTICATOR")
 _LOGGER = logging.getLogger(LOGGER_NAME)
 
@@ -138,6 +138,9 @@ def load_key(self, key, key_type, key_encoding):
         if not (key_type is EncryptionKeyType.SYMMETRIC and key_encoding is KeyEncodingType.RAW):
             raise ValueError("Key type must be symmetric and encoding must be raw.")
 
+        if len(key) * 8 < MinimumKeySizes.HMAC.value:
+            _LOGGER.warning("HMAC keys smaller than %d bits are unsafe" % MinimumKeySizes.HMAC.value)
+
         return key
 
     def validate_algorithm(self, algorithm):

src/dynamodb_encryption_sdk/internal/crypto/jce_bridge/primitives.py

@@ -35,6 +35,7 @@
     WrappingError,
 )
 from dynamodb_encryption_sdk.identifiers import LOGGER_NAME, EncryptionKeyType, KeyEncodingType
+from dynamodb_encryption_sdk.internal.identifiers import MinimumKeySizes
 from dynamodb_encryption_sdk.internal.validators import callable_validator
 
 try:  # Python 3.5.0 and 3.5.1 have incompatible typing modules
@@ -451,7 +452,12 @@ def load_rsa_key(key, key_type, key_encoding):
     if key_type is EncryptionKeyType.PRIVATE:
         kwargs["password"] = None
 
-    return loader(**kwargs)
+    loaded_key = loader(**kwargs)
+
+    if loaded_key.key_size < MinimumKeySizes.RSA.value:
+        _LOGGER.warning("RSA keys smaller than %d bits are unsafe" % MinimumKeySizes.RSA.value)
+
+    return loaded_key
 
 
 _KEY_LOADERS = {rsa: load_rsa_key}

src/dynamodb_encryption_sdk/internal/identifiers.py

@@ -32,13 +32,21 @@
     "SignatureValues",
     "MaterialDescriptionKeys",
     "MaterialDescriptionValues",
+    "MinimumKeySizes",
 )
 
 #: Encoding to use for all text values.
 #: This is noted here for consistency but should not be changed.
 TEXT_ENCODING = "utf-8"
 
 
+class MinimumKeySizes(Enum):
+    """Minimum safe key sizes for algorithms."""
+
+    RSA = 2048
+    HMAC = 128
+
+
 class ReservedAttributes(Enum):
     """Item attributes reserved for use by DynamoDBEncryptionClient"""
 

test/functional/delegated_keys/test_jce.py

@@ -11,11 +11,17 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Functional test suite for ``dynamodb_encryption_sdk.delegated_keys.jce``."""
+from __future__ import division
+
 import pytest
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
 
 from dynamodb_encryption_sdk.delegated_keys.jce import JceNameLocalDelegatedKey
+from dynamodb_encryption_sdk.internal.crypto.jce_bridge.authentication import JAVA_AUTHENTICATOR
+from dynamodb_encryption_sdk.internal.identifiers import MinimumKeySizes
+
+from ..functional_test_utils import RUNNING_IN_TRAVIS, capturing_logger
 
 pytestmark = [pytest.mark.functional, pytest.mark.local]
 
@@ -26,7 +32,7 @@ def _find_aes_key_length(key):
 
 def _find_rsa_key_length(key):
     loaded_key = serialization.load_der_private_key(data=key, password=None, backend=default_backend())
-    return loaded_key._key_size
+    return loaded_key.key_size
 
 
 @pytest.mark.parametrize(
@@ -49,3 +55,28 @@ def test_generate_correct_key_length(algorithm, requested_bits, expected_bits, l
     test = JceNameLocalDelegatedKey.generate(algorithm, requested_bits)
 
     assert length_finder(test.key) == expected_bits
+
+
+def build_short_key_cases():
+    for algorithm in JAVA_AUTHENTICATOR:
+        if algorithm.upper().startswith("HMAC"):
+            message = "HMAC keys smaller than {} bits are unsafe".format(MinimumKeySizes.HMAC.value)
+            yield (algorithm, MinimumKeySizes.HMAC.value, False, message)
+            yield (algorithm, MinimumKeySizes.HMAC.value - 1, True, message)
+
+        elif algorithm.upper().endswith("RSA"):
+            message = "RSA keys smaller than {} bits are unsafe".format(MinimumKeySizes.RSA.value)
+            yield (algorithm, MinimumKeySizes.RSA.value, False, message)
+            yield (algorithm, MinimumKeySizes.RSA.value // 2, True, message)
+
+    message = "RSA keys smaller than {} bits are unsafe".format(MinimumKeySizes.RSA.value)
+    yield ("RSA", MinimumKeySizes.RSA.value, False, message)
+    yield ("RSA", MinimumKeySizes.RSA.value // 2, True, message)
+
+
+@pytest.mark.parametrize("algorithm, key_bits, too_short, error_message", build_short_key_cases())
+def test_warn_on_short_keys(capturing_logger, algorithm, key_bits, too_short, error_message):
+    _test = JceNameLocalDelegatedKey.generate(algorithm, key_bits)
+
+    logging_results = capturing_logger.getvalue()
+    assert (too_short and error_message in logging_results) or (not too_short and error_message not in logging_results)

test/functional/functional_test_utils.py

@@ -15,11 +15,14 @@
 
 import copy
 import itertools
+import logging
+import os
 from collections import defaultdict
 from decimal import Decimal
 
 import boto3
 import pytest
+import six
 from boto3.dynamodb.types import Binary
 from moto import mock_dynamodb2
 
@@ -36,6 +39,7 @@
 from dynamodb_encryption_sdk.structures import AttributeActions
 from dynamodb_encryption_sdk.transform import ddb_to_dict, dict_to_ddb
 
+RUNNING_IN_TRAVIS = "TRAVIS" in os.environ
 _DELEGATED_KEY_CACHE = defaultdict(lambda: defaultdict(dict))
 TEST_TABLE_NAME = "my_table"
 TEST_INDEX = {
@@ -44,7 +48,7 @@
 }
 SECONARY_INDEX = {
     "secondary_index_1": {"type": "B", "value": Binary(b"\x00\x01\x02")},
-    "secondary_index_1": {"type": "S", "value": "another_value"},
+    "secondary_index_2": {"type": "S", "value": "another_value"},
 }
 TEST_KEY = {name: value["value"] for name, value in TEST_INDEX.items()}
 TEST_BATCH_INDEXES = [
@@ -641,3 +645,13 @@ def client_cycle_batch_items_check_paginators(
     e_scan_result = e_client.scan(TableName=table_name, ConsistentRead=True)
     assert not raw_scan_result["Items"]
     assert not e_scan_result["Items"]
+
+
+@pytest.fixture
+def capturing_logger():
+    output_stream = six.StringIO()
+    handler = logging.StreamHandler(stream=output_stream)
+    logger = logging.getLogger()
+    logger.setLevel(logging.DEBUG)
+    logger.addHandler(handler)
+    return output_stream

test/integration/integration_test_utils.py

@@ -18,7 +18,11 @@
 from dynamodb_encryption_sdk.material_providers.aws_kms import AwsKmsCryptographicMaterialsProvider
 
 # convenience imports
-from ..functional import functional_test_utils, hypothesis_strategies
+try:
+    from ..functional import functional_test_utils, hypothesis_strategies
+except (ImportError, ValueError, SystemError):
+    if "AWS_ENCRYPTION_SDK_EXAMPLES_TESTING" not in os.environ:
+        raise
 
 AWS_KMS_KEY_ID = "AWS_ENCRYPTION_SDK_PYTHON_INTEGRATION_TEST_AWS_KMS_KEY_ID"
 DDB_TABLE_NAME = "DDB_ENCRYPTION_CLIENT_TEST_TABLE_NAME"
@@ -52,7 +56,7 @@ def ddb_table_name():
     except KeyError:
         raise ValueError(
             (
-                'Environment variable "{}" must be set to the correct DynamoDB table name'
+                "Environment variable '{}' must be set to the correct DynamoDB table name"
                 " for integration tests to run"
-            ).format(AWS_KMS_KEY_ID)
+            ).format(DDB_TABLE_NAME)
         )