Lookup signer only if signing is requested

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

Author: c00kiemon5ter

src/saml2/entity.py

@@ -225,7 +225,7 @@ def apply_binding(self, binding, msg_str, destination="", relay_state="",
             info["method"] = "POST"
         elif binding == BINDING_HTTP_REDIRECT:
             logger.info("HTTP REDIRECT")
-            if kwargs.get('sigalg', ''):
+            if sign and kwargs.get('sigalg', ''):
                 signer = self.sec.sec_backend.get_signer(kwargs['sigalg'])
             else:
                 signer = None