Privacy protection in ad hoc network becomes key issue in privacy-preserving routing. Earlier works on privacy preserving routing did not address unlinkability or unobservability property due to data packets and control packets are linkable and distinguishable. Existing work presents privacy requirements with Unobservable Secure On-Demand Routing (USOR) scheme which offers complete unlinkability and content unobservability for all types of packets. USOR used combination of group signature and ID-based encryption for secured route discovery. But it unable to detect the propagation of wrong topology information in illusion channel due to the wormhole attack which disrupt the route reply and topology control messages.