Abstract. Due to an increasing number of portable devices over 785million world Internet users, a support for quality of service (QoS) and security becomes a significant issue in Mobile IP networks. Therefore researchers have focused on the handoff with a great effect on QoS, and they proposed Low Latency Handoff and packet forwarding mechanism as representative fast handoff mechanisms. However when we consider a secure handoff using AAA, above two mechanisms implicit a falling-off of QoS because of a frequent session key distribution. Hence we propose a fast and secure handoff mechanism by authenticating MN at MAP instead of AAAH based on a hash function for reducing the frequency of location updates to Home Agent. We evaluate its performance by dividing packet delivery cost, location update cost, and encryption/decryption cost based on the novel analytical approach. The evaluation result shows the better performance with a lower Call-to-Mobility ratio.