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Search Results: 1 - 10 of 372 matches for " Roshan Darshana Yapa "
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The McDonald Generalized Beta-Binomial Distribution: A New Binomial Mixture Distribution and Simulation Based Comparison with Its Nested Distributions in Handling Overdispersion
Chandrabose Manoj,Pushpa Wijekoon,Roshan Darshana Yapa
International Journal of Statistics and Probability , 2013, DOI: 10.5539/ijsp.v2n2p24
Abstract: The binomial outcome data are widely encountered in many real world applications. The Binomial distribution often fails to model the binomial outcomes since the variance of the observed binomial outcome data exceeds the nominal Binomial distribution variance, a phenomenon known as overdispersion. One way of handling overdispersion is modeling the success probability of the Binomial distribution using a continuous distribution defined on the standard unit interval. The resultant general class of univariate discrete distributions is known as the class of Binomial mixture distributions. The Beta-Binomial (BB) distribution is a prominent member of this class of distributions. The Kumaraswamy-Binomial (KB) distribution is another recent member of this class. In this paper we focus the emphasis on the McDonald's Generalized Beta distribution of the first kind as the mixing distribution and introduce a new Binomial mixture distribution called the McDonald Generalized Beta-Binomial distribution(McGBB). Some theoretical properties of McGBB are discussed. The parameters of the McGBB distribution are estimated via maximum likelihood estimation technique. A real world dataset is modeled by using the new McGBB mixture distribution, and it is shown that this model gives better fit than its nested models. Finally, an extended simulation study is presented to compare the McGBB distribution with its nested distributions in handling overdispersed binomial outcome data.
Countermeasures against Bernstein's remote cache timing attack
Janaka Alawatugoda,Darshana Jayasinghe,Roshan Ragel
Computer Science , 2014, DOI: 10.1109/ICIINFS.2011.6038038
Abstract: Cache timing attack is a type of side channel attack where the leaking timing information due to the cache behaviour of a crypto system is used by an attacker to break the system. Advanced Encryption Standard (AES) was considered a secure encryption standard until 2005 when Daniel Bernstein claimed that the software implementation of AES is vulnerable to cache timing attack. Bernstein demonstrated a remote cache timing attack on a software implementation of AES. The original AES implementation can methodically be altered to prevent the cache timing attack by hiding the natural cache-timing pattern during the encryption while preserving its semantics. The alternations while preventing the attack should not make the implementation very slow. In this paper, we report outcomes of our experiments on designing and implementing a number of possible countermeasures.
Accelerating Correlation Power Analysis Using Graphics Processing Units
Hasindu Gamaarachchi,Roshan Ragel,Darshana Jayasinghe
Computer Science , 2014,
Abstract: Correlation Power Analysis (CPA) is a type of power analysis based side channel attack that can be used to derive the secret key of encryption algorithms including DES (Data Encryption Standard) and AES (Advanced Encryption Standard). A typical CPA attack on unprotected AES is performed by analysing a few thousand power traces that requires about an hour of computational time on a general purpose CPU. Due to the severity of this situation, a large number of researchers work on countermeasures to such attacks. Verifying that a proposed countermeasure works well requires performing the CPA attack on about 1.5 million power traces. Such processing, even for a single attempt of verification on commodity hardware would run for several days making the verification process infeasible. Modern Graphics Processing Units (GPUs) have support for thousands of light weight threads, making them ideal for parallelizable algorithms like CPA. While the cost of a GPU being lesser than a high performance multicore server, still the GPU performance for this algorithm is many folds better than that of a multicore server. We present an algorithm and its implementation on GPU for CPA on 128-bit AES that is capable of executing 1300x faster than that on a single threaded CPU and more than 60x faster than that on a 32 threaded multicore server. We show that an attack that would take hours on the multicore server would take even less than a minute on a much cost effective GPU.
Comparison of Digital Water Marking methods
Darshana Mistry
International Journal on Computer Science and Engineering , 2010,
Abstract: In Digital watermarking, image or video is embedded information data within an insensible form for human visual system but in a way that protects from attacks such as common image processing techniques. Spatial domain(Least significant bit(LSB)) and transform domain (Discrete Cosine Transform(DCT) and Discrete Wavelet Transform(DWT))methods are used. DWT is best method because of using embedded zero tree wavelet image compression scheme and high frequency sub bands.
Attitude of Regular Elementary School Teachers towards Inclusive Education
Darshana Sharma
Indian Streams Research Journal , 2012,
Abstract: Education is such a vast arena that it continuously faces certain challenges/ issues and concerns. As a process it has to continuously renew itself by embracing contemporary concerns. Inclusive education is one of our contemporary national concerns in education. In India, inclusive education is a system which aims to provide favorable setting for achieving equal opportunities and full participation for all children with disabilities within general education system. Teachers' attitude is one of the crucial variables in the success of inclusive education.
Magic Frames: The Best of All Possible Virtual Worlds
Darshana Jayemanne
Fibreculture Journal , 2010,
Abstract: If videogame realism is dazzling and flighty, unrealism is a solid and dependable. Unrealistic elements are a feature of all genres and all stages of gaming history. Icons that signify potential actions, pop-up menus, ‘heads-up displays’ (HUDs) quantifying the avatar’s status and various methods of representing the player’s own virtual body (or apparent lack thereof) are all highly unrealistic visual elements. They are also very common across all the genres of gaming. Galloway (2006: 69) argues that the first-person perspective in games tends to marginalise montage in the sense of an editorial cut in cinema. However, a broader definition of the term – one which is not restricted to a cinematic antecedent – would recognise that multiple frames of many videogames are montage. The overwhelming majority of game screens involve overlays or partitions, and gameplay often demands the dynamic navigation of multiple frames. These elements constitute moments of counterplay with regard to the realist ambitions of many videogames.
Qualities Without the Man (Book Review)
Darshana Jayemanne
Cosmos and History : the Journal of Natural and Social Philosophy , 2007,
Abstract: Review of Dominic Pettman, emspan class="sans"Love and Other Technologies: Retrofitting Eros for the Information Age/span/emspan class="sans", New York, /spanFordham University Press, 2006. ISBN: 978-0823226696
Qualities Without the Man (Book Review: Pettman, Love and Other Technologies: Retrofitting Eros for the Information Age)
Darshana Jayemanne
Cosmos and History : the Journal of Natural and Social Philosophy , 2007,
Abstract: Review of Dominic Pettman, Love and Other Technologies: Retrofitting Eros for the Information Age, New York, Fordham University Press, 2006. ISBN: 978-0823226696
DDoS Attack Detection Using Heuristics Clustering Algorithm and Na?ve Bayes Classification  [PDF]
Sharmila Bista, Roshan Chitrakar
Journal of Information Security (JIS) , 2018, DOI: 10.4236/jis.2018.91004
In recent times among the multitude of attacks present in network system, DDoS attacks have emerged to be the attacks with the most devastating effects. The main objective of this paper is to propose a system that effectively detects DDoS attacks appearing in any networked system using the clustering technique of data mining followed by classification. This method uses a Heuristics Clustering Algorithm (HCA) to cluster the available data and Na?ve Bayes (NB) classification to classify the data and detect the attacks created in the system based on some network attributes of the data packet. The clustering algorithm is based in unsupervised learning technique and is sometimes unable to detect some of the attack instances and few normal instances, therefore classification techniques are also used along with clustering to overcome this classification problem and to enhance the accuracy. Na?ve Bayes classifiers are based on very strong independence assumptions with fairly simple construction to derive the conditional probability for each relationship. A series of experiment is performed using “The CAIDA UCSD DDoS Attack 2007 Dataset” and “DARPA 2000 Dataset” and the efficiency of the proposed system has been tested based on the following performance parameters: Accuracy, Detection Rate and False Positive Rate and the result obtained from the proposed system has been found that it has enhanced accuracy and detection rate with low false positive rate.
Secrecy and Performance Analysis of Symmetric Key Encryption Algorithms
Tharindu Darshana Bandara Weerasinghe
International Journal of Information and Network Security (IJINS) , 2012, DOI: 10.11591/ijins.v1i2.438
Abstract: There can be two vital criteria of selecting an algorithm to fulfil one’s encryption requirement. The security level of the cipher (secrecy) and the encryption time (performance). There is less focus on secrecy of ciphers as a security measurement, thus in this research, Shannon’s theories on secrecy of ciphers are used in-order to calculate the average secrecy of each cipher. Depending on the secrecy level and performance of the algorithm, suitable algorithm for encryption can be selected. This paper presents an analysis of some of the widely used symmetric key algorithms which fall under the categories of block and stream ciphers together with the two combined algorithms. [DES, TripleDES, AES, RC2, RC4, Hybrid1 (TripleDES+RC4) and Hybrid2 (AES+RC4) are used]. Analysis is done based on two measurement criteria under two circumstances which is described later in this paper. All the algorithms are implemented in Java using classes available in JAVA package javax.crypto. Separate classes are written to calculate the secrecy of ciphers and the encryption time. Performances of all stream ciphers are higher than that of block ciphers and the combined algorithms have similar performance level to block ciphers. Secrecy level of block ciphers are comparatively higher than that of stream ciphers but there are drastic changes as the data size increases. Hybrid ones have more stable secrecy level.
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