There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

International Journal of Computer and Applications

The Art and Science of Negotiation

As the most prevailing two-factor authentication mechanism, smart-card-based password authentication has been a subject of intensive research in the past two decades, and hundreds of this type of schemes have wave upon wave been proposed. In most of these studies, there is no comprehensive and systematical metric available for schemes to be assessed objectively, and the authors present new schemes with assertions of the superior aspects over previous ones, while overlooking dimensions on which their schemes fare poorly. Unsurprisingly, most of them are far from satisfactory—either are found short of important security goals or lack of critical properties, especially being stuck with the security-usability tension. To overcome this issue, in this work we first explicitly define a security model that can accurately capture the practical capabilities of an adversary and then suggest a broad set of twelve properties framed as a systematic methodology for comparative evaluation, allowing schemes to be rated across a common spectrum. As our main contribution, a new scheme is advanced to resolve the various issues arising from user corruption and server compromise, and it is formally proved secure under the harshest adversary model so far. In particular, by integrating “honeywords”, traditionally the purview of system security, with a “fuzzy-verifier”, our scheme hits “two birds”: it not only eliminates the long-standing security-usability conflict that is considered intractable in the literature, but also achieves security guarantees beyond the conventional optimal security bound.

Two Birds with One Stone: Two-Factor Authentication with Security Beyond Conventional Bound

An efficient and security dynamic identity based authentication protocol for multi-server architecture using smart cards

A secure dynamic identity based authentication protocol for multi-server architecture

Today's real-time systems (RTS) are characterized by managing large volumes of dispersed data making real-time distributed data processing a reality. Large business houses need to do distributed processing for many reasons, and they often must do it in order to stay competitive. So, efficient database management algorithms and protocols for accessing and manipulating data are required to satisfy timing constraints of supported applications. Therefore, new research in distributed real-time database systems (DRTDBS) is needed to investigate possible ways of applying database systems technology to real-time systems. This paper first discusses the performance issues that are important to DRTDBS, and then surveys the research that has been done so far on the issues like priority assignment policy, commit protocols and optimizing the use of memory in non-replicated/replicated environment pertaining to distributed real time transaction processing. In fact, this study provides a foundation for addressing performance issues important for the management of very large real time data and pointer to other publications in journals and conference proceedings for further investigation of unanswered research questions.

Distributed real time database systems: background and literature review

In 2009, Xu et al. found that Lee et al.'s [3] scheme is vulnerable to offline password guessing attack. Xu et al. also demonstrated that Lee and Chiu's [4] scheme is vulnerable to forgery attack. Furthermore, Lee and Chiu's scheme does not achieve mutual authentication and thus can not resist malicious server attack. Therefore, Xu et al. proposed an improved scheme that inherits the merits of Lee et al.'s and Lee and Chiu's schemes and resists different possible attacks. However, we found that Xu et al.'s scheme is vulnerable to forgery attack. This paper presents an improved scheme to resolve the aforementioned problem, while keeping the merits of Xu et al.'s scheme.

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An improvement of Xu et al.'s authentication scheme using smart cards

Integration of MANET with the Internet is a challenging problem. It is important that dynamically deployed wireless ad hoc networks should also gain access to Internet multimedia contents through these fixed networks. When a mobile node in an Ad Hoc network wants to communicate with a node on the Internet, it has to find an efficient and reliable Internet gateway. For this purpose, the node either can send solicitation message or may depend on periodic gateway advertisement. Gateway discovery time has strong influence on packet delay and throughput. In most of the cases, a mobile node uses a number of physical hops to a gateway to communicate with a fixed host connected to an Internet. However, a minimum hop path may not always be efficient if some nodes along the path have longer queue of waiting packets. The focus of this paper is on devising an efficient proactive gateway discovery algorithm that takes into account the size of interface queue in addition to the traditional minimum hop metric to select an efficient gateway. In the MANET domain, AODV routing protocol has been used. This approach also allows an efficient handoff from one gateway to another gateway and still maintains a seamless connectivity to a fixed host. In this paper, impacts of this new metric on the gateway discovery performance are investigated. Simulation results indicate that our protocol outperforms other approaches.

An Efficient Gateway Discovery in Ad Hoc Networks for Internet Connectivity

In this paper, we compare performance of some routing protocols for Mobile Ad-Hoc Networks (MANET's). A Mobile Ad-Hoc Network (MANET) is a collection of wireless mobile nodes that communicates with each other without using any existing infrastructure or centralized administration. In MANET, due to mobility of nodes network topology changes frequently and thus, routing becomes a challenging task. A variety of routing protocols with varying network conditions are analyzed to find an optimized route from a source to some destination. This paper presents performance comparison of four popular mobile ad-hoc network routing protocols i.e. Landmark Ad-hoc Routing Protocol (LANMAR), Location Aided Routing scheme 1 (LAR1), Dynamic MANET On-Demand (DYMO) and Zone Routing Protocol (ZRP) in variable pause time. We used well known network simulator QualNet 5.0 from scalable networks to evaluate the performance of these protocols. The performance analysis is based on different network metrics such as average jitter, packet delivery ratio, average end-to-end delay and throughput.

Anil K. Sarje

Papers

A secure dynamic identity based authentication protocol for multi-server architecture

Distributed real time database systems: background and literature review

An improvement of Xu et al.'s authentication scheme using smart cards

An Efficient Gateway Discovery in Ad Hoc Networks for Internet Connectivity

Comparative performance analysis of LANMAR, LAR1, DYMO and ZRP routing protocols in MANET using Random Waypoint Mobility Model