Abstract: First, conspiracy and replay attacks of authenticated routing for Ad hoc networks (ARAN) have been found in the paper. In order to overcome the above defects of ARAN, an improved protocol is proposed, by appending the identity of the intermediate nodes which broadcast the route discovery packet，that is, routing path. The routing path is signed with the destination node's private key and appended to reply packet. Then, the destination node unicasts reply packet back along the reverse path to the source. The correctness and integrity of the routing path are therefore guaranteed. Finally, the security of eARAN is analyzed by the extended strand spaces, and the analysis proves the correctness of the protocol.