Now-a-days, attacker can obtain information like sequence number and packet type etc. The authors' main aim is to guard all parts of a packet's content, and it is self-governing of solutions on traffic pattern un-observability. In this paper, they define solid secrecy requirements regarding secrecy-maintain routing in MANET. They propose an unobservable secure routing scheme USOR to offer complete unlink ability and content un-observability. USOR is efficient as it uses a novel combination of group signature and ID-based encryption for route outcome. Protection analysis demonstrates that USOR can well protect user privacy against both inside and outside attackers.