Pass proper encryption keys when retrieving the subject NameID

This requires the latest pysaml2 to work properly, as older versions of
get_subject do not accept the optional keys argument.

To have this working without this changeset, one should define the
pysaml2 configuration option `encryption_keypairs`.

Signed-off-by: Ivan Kanakarakis <[email protected]>

Author: c00kiemon5ter

src/satosa/backends/saml2.py

@@ -404,7 +404,7 @@ def _translate_response(self, response, state):
         )
 
         # The SAML response may not include a NameID.
-        subject = response.get_subject()
+        subject = response.get_subject(keys=self.encryption_keys)
         name_id = subject.text if subject else None
         name_id_format = subject.format if subject else None