'Parse a Authentication Request
:param enc_request: The request in its transport format
:param binding: Which binding that was used to transport the message
to this entity.
:return: A dictionary with keys:
consumer_url - as gotten from the SPs entity_id and the metadata
id - the id of the request
sp_entity_id - the entity id of the SP
request - The verified request'

def parse_authn_request(self, enc_request, binding=BINDING_HTTP_REDIRECT):

    return self._parse_request(enc_request, AuthnRequest, 'single_sign_on_service', binding)
