In this paper, the authors define solid privacy requirements regarding privacy-maintain routing in MANET. Then, they propose a secure routing scheme to offer complete unlink ability and content un-observability for all types of packets. It is efficient as it uses a novel combination of group signature and ID-based encryption for route discovery. Security analysis demonstrates that it can well protect user privacy against both inside and outside attackers. Privacy-preserving routing is crucial for some ad hoc networks that require stronger privacy protection. A number of schemes have been proposed to protect privacy in ad hoc networks.