Mobile ad hoc networking (MANET) has become an exciting and important technology in recent years because of the rapid proliferation of wireless devices. In this paper, we present MSRP (secure routing protocol for mobile); a secure routing protocol for mobile ad hoc networks that mitigates the detrimental effects of malicious behavior, as to provide correct connectivity information. The protocol guarantees that fabricated, compromised, or replayed route replies would either be rejected or never reach back the querying node. Furthermore, the protocol responsiveness is safeguarded under different types of attacks that exploit the routing protocol itself. The sole requirement of the protocol is that any two nodes that wish to communicate securely can simply establish a priori shared secret, to be used by their routing protocol modules. Specifically, no assumption is made regarding the intermediate nodes, which may exhibit arbitrary and malicious behavior. The scheme is robust in the presence of a number of non-colluding nodes, and provides accurate routing information in a timely manner.