def decode(response, request):
    """
        Create a credentials object from the given response.

        @type response: L{str}
        @param response: scheme specific response string

        @type request: L{twisted.web.http.Request}
        @param request: The request being processed (from which the response
            was taken).

        @raise twisted.cred.error.LoginFailed: If the response is invalid.

        @rtype: L{twisted.cred.credentials.ICredentials} provider
        @return: The credentials represented by the given response.
        """
