Abstract: To provide an effective method for verifying security of secure dynamic source routing (DSR) protocols, a sufficient-and-necessary condition against active-1-y(y≥1) adversary for secure DSR protocols is proposed. Then a new secure DSR protocol, named effective secure DSR (ESDSR), which is proved to meet this sufficient-and-necessary condition is presented. Compared with the existing secure DSR protocols, the proposed protocol ESDSR can not only defend against active-1-y adversary, but also consume less resource.