Implementing KMS encrypt/decrypt

This adds support for testing the /encrypt and /decrypt endpoints
of Amazon KMS

moto/kms/responses.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import base64
 import json
 import re
 
@@ -213,6 +214,19 @@ class KmsResponse(BaseResponse):
 
         return json.dumps({'Truncated': False, 'PolicyNames': ['default']})
 
+    def encrypt(self):
+        """
+        We perform no encryption, we just encode the value as base64 and then
+        decode it in decrypt().
+        """
+        value = self.parameters.get("Plaintext")
+        return json.dumps({"CiphertextBlob": base64.b64encode(value).encode("utf-8")})
+
+    def decrypt(self):
+        value = self.parameters.get("CiphertextBlob")
+        return json.dumps({"Plaintext": base64.b64decode(value).encode("utf-8")})
+
+
 def _assert_valid_key_id(key_id):
     if not re.match(r'^[A-F0-9]{8}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{12}$', key_id, re.IGNORECASE):
         raise JSONResponseError(404, 'Not Found', body={'message': ' Invalid keyId', '__type': 'NotFoundException'})