Add payload base classes to prepare for simplifying the client

This change adds payload request and response base classes to
prepare for future simplification updates to the current client
architecture. No new tests are required for this change.

kmip/core/messages/payloads/encrypt.py

@@ -19,9 +19,10 @@ from kmip.core import attributes
 from kmip.core import enums
 from kmip.core import primitives
 from kmip.core import utils
+from kmip.core.messages.payloads import base
 
 
-class EncryptRequestPayload(primitives.Struct):
+class EncryptRequestPayload(base.RequestPayload):
     """
     A request payload for the Encrypt operation.
 
@@ -63,9 +64,7 @@ class EncryptRequestPayload(primitives.Struct):
                 authenticated via the Authenticated Encryption Tag.
                 Added in KMIP 1.4.
         """
-        super(EncryptRequestPayload, self).__init__(
-            enums.Tags.REQUEST_PAYLOAD
-        )
+        super(EncryptRequestPayload, self).__init__()
 
         self._unique_identifier = None
         self._cryptographic_parameters = None
@@ -343,7 +342,7 @@ class EncryptRequestPayload(primitives.Struct):
         })
 
 
-class EncryptResponsePayload(primitives.Struct):
+class EncryptResponsePayload(base.ResponsePayload):
     """
     A response payload for the Encrypt operation.
 
@@ -384,9 +383,7 @@ class EncryptResponsePayload(primitives.Struct):
                 authenticated encryption cipher. Optional, defaults to None.
                 Added in KMIP 1.4.
         """
-        super(EncryptResponsePayload, self).__init__(
-            enums.Tags.RESPONSE_PAYLOAD
-        )
+        super(EncryptResponsePayload, self).__init__()
 
         self._unique_identifier = None
         self._data = None