  A mobile ad hoc network (MANET) is a collection of mobile nodes that
communicate with each other by forming a multi-hop radio network. Security
remains a major challenge for these networks due to their features of open
medium, dynamically changing topologies, reliance on cooperative algorithms,
absence of centralized monitoring points, and lack of clear lines of defense.
Design of an efficient and reliable node authentication protocol for such
networks is a particularly challenging task since the nodes are battery-driven
and resource constrained. This paper presents a robust and efficient key
exchange protocol for nodes authentication in a MANET based on multi-path
communication. Simulation results demonstrate that the protocol is effective
even in presence of large fraction of malicious nodes in the network. Moreover,
it has a minimal computation and communication overhead that makes it ideally
suitable for MANETs.
