South African Computer Journal - Volume 55, Issue 1, 2014
Volumes & issues
Volume 55, Issue 1, 2014
Source: South African Computer Journal 55, pp 1 –11 (2014)More Less
The application schema layer of a Database Management System (DBMS) can be modified to produce results that do not reflect the data actually stored in the database. For example, table structures may be corrupted by changing the metadata of a database, or operators of the database can be altered to produce incorrect results when used in queries. Such incorrect results may lead to a forensic examination to determine the cause of the problem. Alternatively, such modifications may be employed as an anti-forensic technique in an attempt to hide the actual data from an investigator when an investigation lead to the examination of a database. In both cases forensic examiners need to be aware of the impact of such metadata on queries and plan their examination of the database accordingly. Different versions of a layer of metadata may exist: a version as found on the computer being investigated, the version that was initially designed, versions from backups, and so on. It is possible that these versions are identical, but subtle ad hoc changes are often made over time and someone with access and malicious intent can introduce changes to modify the behaviour of the DBMS to achieve some nefarious goal.
This paper initially discusses categories of possibilities that exist to (surreptitiously) change the application schema; practical examples are used to illustrate these possibilities.
The paper is based on the premise that a specific combination of DBMS layers of metadata and data should be assembled to test specific hypotheses. For example, questions about how a DBMS should have responded to a specific query and how it does, in fact, respond are both facts that may be important to a forensic investigator. The paper illustrates how such a combination of layers may be of use to examine a specific facet of the behaviour of the DBMS. The paper refers to such a combination of layers as a configuration.
The primary purpose of the paper is to explore methods that may be used to construct a given configuration for testing. A process is proposed on how forensic evidence should be extracted from the application schema layer of a DBMS.
Source: South African Computer Journal 55, pp 12 –24 (2014)More Less
Although computerized retinal image blood vessel segmentation has been extensively researched, there is still room for improvement in the quality of the segmented images. Since retinal image analysis is still widely used in the diagnosis of diabetic retinopathy, efficient and accurate image characterization techniques are required. Previous work has mainly focused on improving segmentation accuracy rates with little regard to the false positives that are produced by illumination variation. This research work presents a hybrid approach towards the segmentation of retinal blood vessels. New approaches towards the reduction of background illumination variation are proposed using normalized Gabor filtering. These are the base-offset encoding and a modified version of an existing zero-integral kernel technique. The valley emphasis automatic thresholding scheme is used to segment the Gabor response images. Experiments are conducted on the DRIVE and STARE retinal image data sets. Accuracy rates of up to 94% are achieved through the zero-integral and base offset methods. This is comparable with results from literature, where the same data sets are segmented using other classification techniques. The median-offset method is found to most effectively reduce background illumination variation.
Source: South African Computer Journal 55, pp 25 –39 (2014)More Less
Problems experienced with website usability can prevent users from accessing and adopting technology, such as e-Government. At present, a number of guidelines exist for e-Government website user experience (UX) design; however, the effectiveness of the implementation of these guidelines depends on the expertise of the website development team and on an organisation's understanding of UX. Despite the highlighted importance of UX, guidelines are rarely applied in South African e-Government website designs. UX guidelines cannot be implemented if there is a lack of executive support, trained staff, budget and user-centred design processes. The goal of this research is to propose and evaluate a methodology (called the "Institutionalise UX in Government (IUXG) methodology") to institutionalise UX in South African Provincial Governments (SAPGs). The Western Cape Government in South Africa was used as a case study to evaluate the proposed IUXG methodology. The results show that the IUXG methodology can assist SAPGs to establish UX as standard practice and improve the UX maturity levels.
Source: South African Computer Journal 55, pp 40 –55 (2014)More Less
This paper sets out to study the views of key stakeholders on the issue of cloud information security within institutions of Higher Education. A specific focus is on understanding trust and the adoption of cloud computing in context of the unique operational requirements of South African universities. Contributions are made on both a methodological and theoretical level. Methodologically, the study contributes by employing interpretivism and using a data-driven approach to thematic analysis in a topic area often studied quantitatively, thus affording researchers the opportunity to gain the necessary in-depth insight into how key stakeholders view cloud security and trust. A theoretical contribution is made in the form of a trust-centric conceptual framework that illustrates how the qualitative data relates to concepts innate to cloud computing trust and adoption. Both these contributions lend credence to the fact that there is a need to address cloud information security with a specific focus on the contextual elements that surround South African universities. The paper concludes with some considerations for implementing and investigating cloud computing services in Higher Education contexts in South Africa.