anchor.diff:          {StringToSign, Signature} ->
               case is_expired(Expires) of
                   true ->
  +                    ?LOG_DEBUG("req_id=~p expired signature (~p) for ~p",
  +                               [ReqId, Expires, Path]),
                       encode_access_denied_error_response(RequestId, Req0, Context);
                   false ->
                       case ((erlang:iolist_to_binary(AWSAccessKeyId) ==
  
positive.code:                         true ->
                              {true, Req0, Context};
                          false ->
                              encode_sign_error_response(AWSAccessKeyId, IncomingSignature, RequestId,
                                                         StringToSign, Req0, Context)
                      end
  
negative.code:             do_standard_authorization(RequestId, IncomingAuth, Req1, Context)
      end.
  
  do_signed_url_authorization(RequestId, Req0, #context{reqid = ReqId} = Context) ->
      AWSAccessKeyId = wrq:get_qs_value("AWSAccessKeyId", Req0),
      Expires = wrq:get_qs_value("Expires", Req0),
      IncomingSignature = wrq:get_qs_value("Signature", Req0),
  