Applying Communicative Teaching Method in English-teaching Classroom

Communicative language teaching is generally accepted in the field of second language teaching. In this paper, the author introduces a model of communicative language teaching. The authors also mention some practical requirements and methods in the application of this model, such as authentic materials and group work.

An Anonymous Authentication Scheme for Plugin Electric Vehicles Joining to Charging/Discharging Station in Vehicle-to-Grid(V2G) Networks

Incorporating electric vehicles into smart grid,vehicle-to-Grid(V2G) makes it feasible to charge for large-scale electric vehicles,and in turn support electric vehicles,as mobile and distributed storage units,to discharge to smart grid.In order to provide reliable and efficient services,the operator of V2 G networks needs to monitor realtime status of every plug-in electric vehicle(PEV) and then evaluate current electricity storage capability.Anonymity,aggregation and dynamic management are three basic but crucial characteristics of which the services of V2 G networks should be.However,few of existing authentication schemes for V2 G networks could satisfy them simultaneously.In this paper,we propose a secure and efficient authentication scheme with privacy-preserving for V2 G networks.The scheme makes the charging/discharging station authenticate PEVs anonymously and manage them dynamically.Moreover,the monitoring data collected by the charging/discharging station could be sent to a local aggregator(LAG)in batch mode.In particular,time overheads during verification stage are independent with the number of involved PEVs,and there is no need to update the membership certificate and key pair before PEV logs out.

A novel secure group RFID authentication protocol

The trend of researching group radio frequency identification devices（RFID） authentication protocol has become increasingly popular in recent years. One of the newest work in this area is from Batina and Lee, they presented a privacy-preserving multi-players grouping-proof protocol based on the elliptic curve cryptography（ECC）, and claimed their protocol have the ability to resist five potential attacks, including compromised tag attack, man-in-the-middle attack, colluding tags attack, etc. In this paper, we first take a counterexample to demonstrate their protocol is vulnerable to compromised tag attack. Then we propose a novel secure RFID authentication protocol, and analyze its security by merging formal analysis, provable security, and mathematical inductive method, so as to solve the weakness of Batina and Lee＇s work. Furthermore, compared with another two classic protocols（secure ownership transfer protocol（SOTP） and secure multiple group ownership transfer protocol（SMGOTP））, the performance analysis show that our protocol provides not only a lower tags＇ communication cost at about 50.0% and 14.3%, but also a lower reader＇s computation cost（approximate 14.5% and 55.1% respectively）, when transferring a large number of tags.

LEGA:A Lightweight and Efficient Group Authentication Protocol for Massive Machine Type Communication in 5G Networks

Massive machine type communication(mMTC)is anticipated to be an essential part of fifth generation(5G)networks.The main challenge for mMTC devices(mMTCDs)is the design of an access authentication scheme that can fulfill the security and privacy requirements of 5G applications,which have specific conditions,including rigorous latency and si-multaneous access.Thus,a novel 5G authentication and key agreement(5G-AKA)protocol was introduced by the 3rd generation partnership project(3GPP)to achieve mMTCD access authentication.However,5G-AKA protocol comes with some security vulnerabilities and significant delay for real-time mMTC applications,particularly when mMTCDs concurrently roam into new networks.In order to address the real-time secure and efficient access issues of multiple mMTCDs,this paper proposes a lightweight and efficient group authen-tication protocol for mMTC in 5G wireless networks.The proposed protocol,which integrates bilinear maps and an aggregate certificateless signature mechanism,can achieve several security goals,including avoidance of signaling congestion in the authentication process,mutual authentication,session key agreement,perfect forward/backward secrecy,and masked attack and key escrow resistance.Compared to existing conventional protocols,the proposed protocol demonstrates robust security and improved performance in terms of signaling cost authentication,bandwidth consumption and compu-tational cost.