In mobile ad hoc networks (MANETs), multi-hop message relay is the common way for nodes to communicate and participate in network operations, making routing a primary issue. The early research efforts on MANET routing focused mainly on effectiveness and efficiency under the assumption of perfectly cooperative networks. However, MANETs may not be such a friendly environment for various reasons. Routing protocols without any security feature may put entire network at risk. As security becomes an increasingly popular topic, secure mobile ad hoc routing is attracting more and more research attention. In this paper, we conduct a survey on the state-of-art work in this field.