Vehicular Ad-hoc Network (VANET) is a collection of interconnected smart vehicles. Underlying wireless technology enables communication within vehicles as well as between road infrastructure and vehicles. Security plays a vital role during transmission of safety and important messages due to the open-access environment of VANET. Several security challenges need to be addressed in order to enable a real-time use of VANET. The significant goal of the paper is to propose a Secure Anonymous Routing Protocol (SARP) that is the extension of ACO-IBR. The SARP uses anonymous authentication methodology alongwith bilinear paring technique. The protocol verifies authenticity of the vehicles and integrity of the messages that participate in the communication process at the route discovery phase and it is resistant to various attacks. The simulation based QoS performance of the SARP routing protocol is evaluated using collision rate, packet delivery ratio, delay & throughput. SARP observed 0.023, 0.048, 0.028s less delay and 8.63, 11.52, 10.49 less overhead as compared to the ACO-IBR, GPSR and IBR. The performance is evaluated in terms of communication overhead and computational time that enhance security efficiently. It is observed that SARP requires 224.4ms computational time and 568-byte communication overhead for 100 vehicles.