User authentication and undeniable billing support for agent-based roaming service in WLAN/cellular integrated mobile networks

In this paper, a framework of authentication and undeniable billing support for an agentbased roaming service in WLAN/cellular networks interworking networks is proposed. This framework circumvents the requirement of peer-to-peer roaming agreements to provide seamless roaming service between WLAN hotspots and cellular networks operated by independent wireless network service providers. Within the framework, an adaptive authentication and an event-tracking scheme have been developed, which allow the application of undeniable billing service to cellular network even when it still uses a traditional authentication scheme. The proposed modified dual directional hash chain (MDDHC) based billing support mechanism features mutual non-repudiation. Security analysis and overhead evaluation demonstrate that the proposed framework is secure and efficient. 2008 Elsevier B.V. All rights reserved.