JWCN_V2_N1_RP1 R. Narmadha Malarkkan Journal On Wireless Communication Networks 2320 - 2351 2 1 1 8 LTE, WIMAX, Authentication Protocols, Cryptography Key Length The integration of LTE –WiMax wireless mobility aids in seamless mobility and cost effective mobile data services with the use of IP core and OFDMA air interface technology. The onslaught of 3G/4G and Wifi/WiMax interworking capabilities introduces a multitude of possibilities like security and Quality of Service (QoS). Each network has several similarities and has its own technology for authentication and link layer security. The interworking is performed on a data link layer using EAP authentication protocol by integrating key authentication procedure. In this paper, security key management for various protocols and its numerical analysis are presented across interworking domain. Interworking security is isolated in view of the fact that the authentication protocol has its limitation. It is desirable to avoid several round trips, delays in handover, computational overhead, hence a fast re-authentication procedure has been proposed in LTE-WiMax network. April - June 2013 Copyright © 2013 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=2305