Sathiamoorthy Manoharan

A performance comparison of SQL and NoSQL databases

With the current emphasis on “Big Data”, NoSQL databases have surged in popularity. These databases are claimed to perform better than SQL databases. In this paper we aim to independently investigate the performance of some NoSQL and SQL databases in the light of key-value stores. We compare read, write, delete, and instantiate operations on key-value stores implemented by NoSQL and SQL databases. Besides, we also investigate an additional operation: iterating through all keys. An abstract key-value pair framework supporting these basic operations is designed and implemented using all the databases tested. Experimental results measure the timing of these operations and we summarize our findings of how the databases stack up against each other. Our results show that not all NoSQL databases perform better than SQL databases. Some are much worse. And for each database, the performance varies with each operation. Some are slow to instantiate, but fast to read, write, and delete. Others are fast to instantiate but slow on the other operations. And there is little correlation between performance and the data model each database uses.

On GPS Tracking of Mobile Devices

Tracking living beings and devices using the Global Positioning System (GPS) has become prevalent and indispensable over the last few years. Applications range from military and national security to personal safety and comfort. This paper reviews some of the recent application areas and discusses the benefits and issues of GPS tracking. It then presents a software architecture of a general tracking system to locate lost and misplaced devices (and those that carry such devices).

A security analysis of the OAuth protocol

The OAuth 2.0 authorization protocol standardises delegated authorization on the Web. Popular social networks such as Facebook, Google and Twitter implement their APIs based on the OAuth protocol to enhance user experience of social sign-on and social sharing. The intermediary authorization code can be potentially leaked during the transmission, which then may lead to its abuse. This paper uses an attacker model to study the security vulnerabilities of the OAuth 2.0 protocol. The experimental results show that common attacks such as replay attacks, impersonation attacks and forced-login CSRF attacks are capable of compromising the resources protected by the OAuth 2.0 protocol. The paper presents a systematic analysis of the potential root causes of the disclosed vulnerabilities.

An Empirical Analysis of RS Steganalysis

Steganography is the science of hiding messages within some cover media.The intent is usually covert communication, but steganography is equally used for digital watermarking of media. Messages can be hidden in any media. Typical media include digital images, sound, and video. Steganalysis is the science of detecting the presence of hidden messages in media. Most steganalysis techniques search for artifacts created by the message hiding process. A simple and commonly-used steganograpy technique is LSB steganography where the least-significant bits (LSB) of data values in a media file are altered to hide a message. There are also a number of published steganalysis techniques for LSB steganography. This paper presents an empirical analysis of an LSB steganalysis technique called the RS steganlysis.

Dynamic Content Management and Delivery for Mobile Devices

Unlike desktop computers, mobile devices vary widely in terms of their capability. Screen size, colour depth, and supported file types are just some examples of where the variations are. Tailoring content to suit the capability of a device has been a research and practical problem for some time, and a variety of solutions exist. Content adaptation to cater for device variations is the focus of this paper. It presents the design and implementation of a content management and delivery system that adapts content based on device capability. The system is capable of handling a variety of content types and is extensible to allow inclusion of others.

An assessment of assignment schemes for dependency graphs

Abstract The recent past has seen a number of publications proposing assignment schemes that do not ignore communication costs. Yet, little effort has been made to comparatively assess the performance and end-results of these schemes. This paper presents a comparative assessment of assignment schemes for dependency graphs that take into account the communication costs. To generate an assignment, some parameters describing the program model will be required. In many cases, accurate estimation of these parameters is hard. It is thought that inaccuracies in the estimation would lead to poor assignments. This paper investigates this speculation and presents experimental evidence that shows such inaccuracies do not greatly affect the quality of the assignments.

Effect of task duplication on the assignment of dependency graphs

Abstract This paper analyses the effect of task duplication on the assignment of task dependency graphs onto concurrent processor systems. It augments work-greedy assignment schemes with task duplication (TD). Such augmentation results in a time-complexity increase which is well below that of comparable assignment schemes with TD. The paper shows empirical results comparing the augmented assignment schemes.

Advance in vision-based driver assistance

Vision-based driver assistance is an active safety measure currently under development in various car companies and research institutes worldwide. The paper informs about related activities at The University of Auckland, focussing on stereo vision, performance evaluation, provided test data, and currently developed components.

Experiments with and Enhancements to Echo Hiding

Echo hiding is a steganographic technique that hides messages in audio.This paper proposes a scheme that improves the robustness of echo hiding.A self-synchronizing code set called the T-Codes is used to encode messagesprior to their concealment using echo hiding. This is shown to increasemessage recovery and in turn robustness of echo hiding.

Software Licensing: A Classification and Case Study

Software licensing schemes are controls put in software to grant or deny the use of the software. It plays an important part in the distribution and the control of software. This paper reviews some of the technologies behind software licensing schemes and presents a classification and a case study.