fix JceNameLocalDelegatedKey.generate to only accept number of bits to generate rather than bytes for symmetric and bits for RSA

Author: mattsb42-aws

src/dynamodb_encryption_sdk/delegated_keys/jce.py

@@ -11,6 +11,8 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Delegated key that JCE StandardName algorithm values to determine behavior."""
+from __future__ import division
+
 import logging
 import os
 
@@ -32,17 +34,17 @@
 def _generate_symmetric_key(key_length):
     """Generate a new AES key.
 
-    :param int key_length: Required key length in bytes
+    :param int key_length: Required key length in bits
     :returns: raw key, symmetric key identifier, and RAW encoding identifier
     :rtype: tuple of bytes, EncryptionKeyType, and KeyEncodingType
     """
-    return os.urandom(key_length), EncryptionKeyType.SYMMETRIC, KeyEncodingType.RAW
+    return os.urandom(key_length // 8), EncryptionKeyType.SYMMETRIC, KeyEncodingType.RAW
 
 
 def _generate_rsa_key(key_length):
     """Generate a new RSA private key.
 
-    :param int key_length: Required key length in bytes
+    :param int key_length: Required key length in bits
     :returns: DER-encoded private key, private key identifier, and DER encoding identifier
     :rtype: tuple of bytes, EncryptionKeyType, and KeyEncodingType
     """
@@ -151,7 +153,7 @@ def generate(cls, algorithm, key_length=None):
         """Generate an instance of this DelegatedKey using the specified algorithm and key length.
 
         :param str algorithm: Text description of algorithm to be used
-        :param int key_length: Size of key to generate
+        :param int key_length: Size in bits of key to generate
         :returns: Generated delegated key
         :rtype: dynamodb_encryption_sdk.delegated_keys.DelegatedKey
         """

src/dynamodb_encryption_sdk/materials/wrapped.py

@@ -11,8 +11,6 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Cryptographic materials to use ephemeral content encryption keys wrapped by delegated keys."""
-from __future__ import division
-
 import base64
 import copy
 
@@ -140,7 +138,7 @@ def _generate_content_key(self):
         args = self._content_key_algorithm.split('/', 1)
         content_algorithm = args[0]
         try:
-            content_key_length = int(args[1]) // 8
+            content_key_length = int(args[1])
         except IndexError:
             content_key_length = None
         content_key = JceNameLocalDelegatedKey.generate(

test/functional/delegated_keys/__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.
+"""Dummy stub to make linters work better."""

test/functional/delegated_keys/test_jce.py

@@ -0,0 +1,48 @@
+# 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.
+"""Functional test suite for ``dynamodb_encryption_sdk.delegated_keys.jce``."""
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+import pytest
+
+from dynamodb_encryption_sdk.delegated_keys.jce import JceNameLocalDelegatedKey
+
+pytestmark = [pytest.mark.functional, pytest.mark.local]
+
+
+def _find_aes_key_length(key):
+    return len(key) * 8
+
+
+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
+
+
+@pytest.mark.parametrize('algorithm, requested_bits, expected_bits, length_finder', (
+    ('AES', 256, 256, _find_aes_key_length),
+    ('AESWrap', 256, 256, _find_aes_key_length),
+    ('RSA', 4096, 4096, _find_rsa_key_length),
+    ('HmacSHA512', 256, 256, _find_aes_key_length),
+    ('HmacSHA256', 256, 256, _find_aes_key_length),
+    ('HmacSHA384', 256, 256, _find_aes_key_length),
+    ('HmacSHA224', 256, 256, _find_aes_key_length),
+    ('SHA512withRSA', 4096, 4096, _find_rsa_key_length),
+    ('SHA256withRSA', 4096, 4096, _find_rsa_key_length),
+    ('SHA384withRSA', 4096, 4096, _find_rsa_key_length),
+    ('SHA224withRSA', 4096, 4096, _find_rsa_key_length)
+))
+def test_generate_correct_key_length(algorithm, requested_bits, expected_bits, length_finder):
+    test = JceNameLocalDelegatedKey.generate(algorithm, requested_bits)
+
+    assert length_finder(test.key) == expected_bits

test/functional/functional_test_utils.py

@@ -211,7 +211,7 @@ def _some_algorithm_pairs():
 def _all_possible_cmps(algorithm_generator):
     """Generate all possible cryptographic materials providers based on the supplied generator."""
     # The AES combinations do the same thing, but this makes sure that the AESWrap name works as expected.
-    yield _build_wrapped_jce_cmp('AESWrap', 32, 'HmacSHA256', 32)
+    yield _build_wrapped_jce_cmp('AESWrap', 256, 'HmacSHA256', 256)
 
     for builder_info, args in itertools.product(_cmp_builders.items(), algorithm_generator()):
         builder_type, builder_func = builder_info
@@ -229,9 +229,6 @@ def _all_possible_cmps(algorithm_generator):
             sig_key_length=signing_key_length
         )
 
-        if encryption_algorithm == 'AES':
-            encryption_key_length //= 8
-
         yield pytest.param(
             builder_func(
                 encryption_algorithm,