Explicitly name the default symmetric scheme

Signed-off-by: Ivan Kanakarakis <ivan.kanak@gmail.com>

Author: c00kiemon5ter

src/saml2/cryptography/symmetric.py

@@ -13,7 +13,7 @@
 import cryptography.hazmat.primitives.ciphers as _ciphers
 
 
-class Default(object):
+class Fernet(object):
     """The default symmetric cryptography method."""
 
     @staticmethod
@@ -51,6 +51,7 @@ def decrypt(self, ciphertext):
         return plaintext
 
 
+
 class AESCipher(object):
     """[deprecated] Symmetric cryptography method using AES.
 
@@ -164,3 +165,7 @@ def decrypt(self, msg, alg='aes_128_cbc', padding='PKCS#7', b64dec=True):
             idx = bytearray(res)[-1]
             res = res[:-idx]
         return res
+
+
+class Default(Fernet):
+    """Default class is saml2.cryptography.symmetric.Fernet"""