Earticle

A scheme, which uses flexible cryptographic key management upon adaptable time-token constraint for a user hierarchy access control (UHAC) scheme, is proposed in this paper. For adapting the changeability in a UHAC system, we propose a technique of assigning independent time-token which is distributed by a trusted agency server to reply an authorized user for once secure access request. The key feature of the technique is to adapt some secure parameters in distributed time-token for responding to each legal access request. Further, all class keys will be updated proactively by the concept of proactive key management, which makes the advantage that is proven and free from the scenario of the collusive attack example which proposed by Yi et al. in [18]. This cryptographic key assignment scheme based on the difficulty in solving a discrete logarithm, with adaptable time-token constraint, can achieve better security and more efficient management, than the conventional UHAC scheme. Besides, our scheme provides a flexible manner and dynamic key management to increase the availability of user access in UHAC structure.

In the evolution of traditional telecom network towards a converged next generation network, Inter-working is always challenging due to different name spaces and routing mechanism across different communities. Most existing Inter-working solutions are terminal based solutions. They require mobile phone or PC users to install multiple client-side applications on the devices, such as, Google talk client, Skype client, and MSN client, etc. In order to avoid too many client applications running on mobile terminals that normally have a limited resource, a network based Inter-working solution is desired. An IMS based Inter-working solution for multi-media services is proposed. It enables an IMS subscriber make use of a single SIP user agent to communicate with the other users who might have communication means other than IMS based devices. The solution consists of two parts in the network: one is the conference like service that resides at the originating side and provides “forking service”; the other is the Inter-working gateway service that provides the protocol conversion service. The detailed technical description of the proposed solution is described hereafter. The corresponding use cases are studied. The application of the solution to the Group Communication service, e.g. an ad-hoc group or pre-defined group multimedia service, is also discussed. The benefits of the proposed solution for end users and operators are highlighted respectively.

Push-to-Talk (PTT) is a half-duplex and one-to-many voice group communication. In past decades, PTT service has been widely adopted in various areas, including practical military, police, security, rescue, and emergency radio communication, etc. In addition, PTT service has also annunciated being an IP Multimedia Subsystem (IMS)-based service defined by Open Mobile Alliance (OMA), which is called Push-to-Talk over Cellular (PoC).Context-aware computing derived from the field of ubiquitous computing as a technique for imbuing application services with an awareness of users’ surroundings and situations for achieving transparent interaction. Thus, a user can obtain some reasonable and proper services among context-aware interactions. In this paper we try combine the features of PoC and context-aware service to implement a context-aware PoC service based on the Open IMS core. The context-aware PoC service can be aware to filter context information and to form an applicable PoC session according to the current contexts of participant PoC users. By the way, our implemented context-aware PoC service can be realizedly used to play an applicable IMS application service in the next generation network (NGN).

Ad hoc networks are highly dynamic routing networks cooperated by a collection of wireless mobile hosts without any assistance of a centralized access point. Secure Efficient Ad hoc Distance Vector (SEAD) is a proactive routing protocol, based on the design of Destination Sequenced Distance Vector routing protocol (DSDV). SEAD provides a robust protocol against attackers trying to create incorrect routing state in the other node. However, it does not provide a way to prevent an attacker from tampering the next hop or the destination field in route update. In this paper, we propose an I-SEAD protocol to solve the problem. A series of simulation experiments are conducted to evaluate the performance.

The mobile Internet has become increasingly visible in everyday life. As mobile Internet penetration leverages content business opportunities, it is crucial to identify methodologies to fit mobile-specific demands, e.g. regularity. Regularity is one of the important measures to capture easy-come, easy-go mobile users, especially in subscription-based mobile services. The author proposes a method called the "time slot count in window" method (TCW-method) to efficiently capture regular users, while relaxing the explicit splits among time slots with visits. The author shows the case study result from 2001-2002 commercial service logs. Case studies conducted in 2001-2002 with commercial news service subscribers show that the relaxation in the proposed method loses 2-3 % in the true positive rate of regularity as a binary classifier. The results show high true positive rate, 88-91 % for the Carrier-A case and 86-92 % in the Carrier-C case. Experimental results show that the method is promising for identifying revisiting users under mobile-specific constraints..

DVD VR(Video Recording) is a logic format adopted by most home consumer DVD recorder machines to record real-time TV and multimedia content on DVD+R/RW or DVD-R/RW blank discs. However, DVD VR format can only be recognized and played by the DVD recorder itself. To achieve forward compatibility and playability, the recorder provides a function called disc finalizing process which closes every tracks and sessions of a DVD VR disc and changes its logic format from DVD VR to DVD-Video to make it playable on generic DVD-Video compatible players. Unfortunately, disc finalizing process provided by DVD recorder is very unstable and unreliable due to various uncertain reasons. This unreliable finalizing process often and easily produces failure discs which are neither in correct DVD VR format nor in DVD-Video format. Thus, these discs become unrecognized, and can no longer be played any more by any DVD players or recorders. This paper proposes an extension of software solution with packet reading which is capable of reading and playing non-finalized, finalizing-failure or other recording-failure DVD VR discs.

Most of the national critical key infrastructure, such as power, piped gas and water supply facilities, or the high-speed railroad, is run on the SCADA (Supervisory Control and Data Acquisition) system. Recently, concerns have been raised about the possibility of these facilities being attacked by cyber terrorists, hacking, or viruses. Thus, it is time to adopt the relevant security management techniques. This study analyzes the vulnerabilities of SCADA systems through scenarios, designs a test-bed to prove such vulnerabilities, and suggests security devices..