Browsing by Author "Opatha, N.W.K.D.V.P."

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Development of A Chaos Based Image Encryption and Decryption Algorithm for Color Images
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Opatha, N.W.K.D.V.P.
Image encryption and decryption are important in secure transmission and storage of digital images. Image encryption and decryption algorithms are basically categorized into three categories, i.e., traditional ciphers, chaos based techniques and visual cryptography. The goal of this research is to implement an efficient image encryption and decryption algorithm for color (RGB) images, by using chaos based techniques, while analyzing the issues prevailing in the existing chaos based algorithms. In recent years, many chaos based algorithms have been developed, as their suitability in image encryption and decryption is significant. Prior research studies have highlighted the different methodologies in using chaos based techniques, to encrypt and decrypt images, while identifying the issues in them. The research study was conducted as an experimental study. A new technique was proposed to generate the key, which was based on random mathematical permutation. The proposed key was a combination distinct keys for red, green and blue panels of an image. Pixel intensity values were replaced separately in the three panels, based on the key that was generated. Moreover, block transformation was introduced, to be performed, subsequently after replacing the pixel intensity values. The block transformation had three different patterns for three color panels. Finally, encrypted image was received by combining these three layers. Decryption was the reverse process of the encryption process. The algorithm was tested for its accuracy and its validity. Encrypted images provided a flat histogram, which demonstrated the validity. Application of noise removal filter on the encrypted image, did not provide the plain image. Key space of the proposed method was 8.578177753 * 10^506 for one panel, and the key file was a combination of 3 distinct keys of the given nature, which was larger and complex than the other methods. Average execution time (in seconds) for encryption and decryption are 0.012 and 0.014 respectively, which is lower than the other methods. Correlation coefficient between the plain image and cipher image were lower than the existing techniques, and thus this method demonstrated satisfactory results compared with the existing chaos based image encryption and decryption algorithms.
Study on Theory and Practice in Software Quality Assurance (With Special Reference to Information Technology Professionals in Colombo, Sri Lanka)
(3rd International Conference on Advances in Computing and Technology (ICACT ‒ 2018), Faculty of Computing and Technology, University of Kelaniya, Sri Lanka., 2018) Opatha, N.W.K.D.V.P.
A software product is developed or engineered by a set of professionals, and they support and maintain it over a long period of time. Software Quality Assurance (SQA) plays an imperative role in achieving high quality software. SQA process should be carried out from the inception of the project till its maintenance. This research is expected to study the gap between the theories and practical approaches related to SQA by refereeing to Information Technology (IT) professionals in software firms in Colombo, Sri Lanka. Further, it was aimed to explore the differences in SQA activities performed, and perception of IT professionals related to testing and SQA, while identifying the reasons to have/not to have a separate SQA section. The study was conducted as a descriptive study, and the selected sample size was 40. Major reasons identified for not having the SQA section were, the company being small scale with few projects (47.1%) and to reduce the cost (29.1%). The Activities that are performed by companies with a separate SQA section and without a separate SQA section are far too different. Testing programs and retesting them after correction were most popular among both types. The companies enriched with SQA section performed various other activities apart from testing. A significant proportion of the respondents (50%) were not even aware of the SQA standards, and among them, the largest proportion (82%) did not have a separate SQA section. In considering the perception of the professionals with regard to SQA and testing, there is a significant difference among both groups. Furthermore, largest proportion (39%) of the professionals agreed that more up-to-date knowledge regarding the entire process is required, which can cover all the activities and scenarios, while having the presence of SQA from the very beginning to the end of the project. Finally, having a separate SQA section would greatly benefit the companies, and it will contribute to improve the quality, with enriched set of activities. A gap truly exists in between what is emphasized in theories and the way they have been implemented practically in SQA.