In ad hoc network all nodes are mobile and can be connected dynamically in an arbitrary manner. No default router is available for routing. Since in an ad hoc network, a significant concern is the ability to route in the presence of byzantine failures which include nodes that drop, fabricate, modify, or mis-route packets in an attempt to disrupt the routing service. As byzantine fault occur in Ad-hoc On-demand Distance Vector (AODV) protocol. In this paper, the authors propose three methods for securing AODV protocol from byzantine attacks by using signature based techniques.