def serialize(material_description):
# type: (Dict[Text, Text]) -> dynamodb_types.BINARY_ATTRIBUTE
"""Serialize a material description dictionary into a DynamodDB attribute.
:param dict material_description: Material description dictionary
:returns: Serialized material description as a DynamoDB binary attribute value
:rtype: dict
:raises InvalidMaterialDescriptionError: if invalid name or value found in material description
"""
material_description_bytes = bytearray(_MATERIAL_DESCRIPTION_VERSION)
# TODO: verify Java sorting order
for name, value in sorted(material_description.items(), key=lambda x: x[0]):
try:
material_description_bytes.extend(encode_value(to_bytes(name)))
material_description_bytes.extend(encode_value(to_bytes(value)))
except (TypeError, struct.error):
raise InvalidMaterialDescriptionError(
'Invalid name or value in material description: "{name}"="{value}"'.format(
name=name,
value=value
)
)
return {Tag.BINARY.dynamodb_tag: bytes(material_description_bytes)}
def _decrypt_initial_material(self, encryption_context):
# type: (EncryptionContext) -> bytes
"""Decrypt an encrypted initial cryptographic material value.
:param encryption_context: Encryption context providing information about request
:type encryption_context: EncryptionContext
:returns: Plaintext of initial cryptographic material
:rtype: bytes
"""
key_id = self._select_key_id(encryption_context)
self._validate_key_id(key_id, encryption_context)
kms_encryption_context = self._kms_encryption_context(
encryption_context=encryption_context,
encryption_description=encryption_context.material_description.get(
MaterialDescriptionKeys.CONTENT_ENCRYPTION_ALGORITHM.value),
signing_description=encryption_context.material_description.get(
MaterialDescriptionKeys.ITEM_SIGNATURE_ALGORITHM.value),
)
encrypted_initial_material = base64.b64decode(
to_bytes(
encryption_context.material_description.get(
MaterialDescriptionKeys.WRAPPED_DATA_KEY.value)))
kms_params = dict(CiphertextBlob=encrypted_initial_material,
EncryptionContext=kms_encryption_context)
if self._grant_tokens:
kms_params["GrantTokens"] = self._grant_tokens
# Catch any boto3 errors and normalize to expected UnwrappingError
try:
response = self._client(key_id).decrypt(**kms_params)
return response["Plaintext"]
except (botocore.exceptions.ClientError, KeyError):
message = "Failed to unwrap AWS KMS protected materials"
_LOGGER.exception(message)
raise UnwrappingError(message)
def _transform_string_value(value):
# type: (dynamodb_types.STRING) -> bytes
"""
:param value: Input value
:type value: bytes or str
:returns: bytes value
:rtype: bytes
"""
return to_bytes(value)
def test_to_bytes(data, expected_output):
test = to_bytes(data)
assert test == expected_output