PURSE 2006

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https://ir.lib.pdn.ac.lk/handle/20.500.14444/53

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A casestudy on password security evolution
(University of Peradeniya, Sri Lanka, 2006-11-30) Sandirigama, M.; Weragama, N. S
As the Internet and Mobile applications have been increasing in the recent past, the need for authentication over remote servers and telephones has become very important. The need of authentication is essential as the private data sent over the Internet have risk of being wiretapped. Existing password authentication schemes can be divided into two types, one requires only the weak password and the other must use the strong password. The main objective of this case study is to present a review on the evolution of the strong password protocols. Starting with the earliest password authentication protocols such as Lamport I, CINON and the PERM, the study comprehensively analyzes the most recent protocols such as SAS-2 and SPAPA. The newest protocol SPAPA stands for hash-based Strong Password Authentication Protocol with user Anonymity . The user's anonymity is highly required in a hostile environment as it prevents observing the user 's activity. Also, the SPAPA protocol is very simple and contains only hash functions and XOR operations as compared to the earlier versions, which are suitable for power and computation constrained smart card applications. The SPAPA protocol is tested and verified to be secure from Stolen Smart Card or Online Guessing Attack, Offline Guessing Attack, Stolen Verifier Attack, Replay Attack and Denial of Service (DoS) Attack. In addition, all the attacks performed on each of these protocols are covered in this case study as well. The common pattern in evolution and the details of the attacks that compromised the security measures in each of the protocol are taken into account.
Candida in oral lichen planus: a histopathological analysis
(University of Peradeniya, Sri Lanka, 2006-11-30) Jayasooriya, P. R.; Tennakoon, P. B.; Amaratunge, E. A. P. D.
Oral lichen planus (OLP) is a chronic inflammatory disorder of unknown etiology and Candida species are common fungal organisms that live as commensals in the oral cavity. Although the yeast forms of Candida are non-pathogenic, hyphal forms have been implicated in the etiology of several disease processes. Evaluation of scientific literature regarding colonization of Candida species in OLP revealed controversial results. Therefore, the aim of the study was to evaluate the prevalence of Candida histopathologically in OLP lesions and to correlate the presence of Candida with the clinical form of the disease. Sixty five formalin fixed paraffin embedded histopathologically confirmed OLP samples were used for the study. Paraffin embedded blocks were prepared from incisional biopsies obtained prior to treatment with steroids. In addition, fifteen previously diagnosed Frictional keratosis tissue blocks were used as the control. Clinical features such as age, gender and type of lesion (reticular, plaque like or erosive) were obtained from the request forms while only OLP and Frictional keratosis lesions involving buccal mucosa were analyzed in the present study to avoid bias. From each block 4µm thick tissue sections were stained with Diastase resistant periodic acid Schiff (D-PAS) stain to evaluate the presence of candidal hyphae invading in to the superficial epithelium of OLP lesions. The results revealed histopathological evidence of Candida in 26% (17/65) of OLP and in 0% (0/15) Frictional keratosis lesions. This finding was statistically significant when analyzed by Chi-square test at 5% level. The mean age of OLP patients with and without candidal infection was 41.4 and 42.7 years respectively. Forty seven percent and 41% of OLP lesions with and without candidal infection were present in males while the remaining lesions were present in females. As such no statistically significant differences could be established between age/gender and candidal carriage in OLP lesions. Forty two percent, 31% and 26% of erosive, plaque like and reticular OLP lesions showed superficial candidal infection respectively. Although not statistically significant Candida was more frequently found in erosive form compared to plaque like or reticular OLP lesions. In conclusion, even though candidal hyphae have been identified in 26% of OLP lesions, it is not adequate to establish an etiological role of Candida in OLP as the presence of Candida can also be attributed to secondary infection. However, as the hyphal forms are pathogenic, in Candida positive OLP patients, addition of antifungal medication may provide beneficial results
Between two hegemonies: the double marginalisation of "under-class" tamil users of English
(University of Peradeniya, Sri Lanka, 2006-11-30) Williams, M.
We have come a long way from the days when Sri Lankan English was seen as a collection of errors or a "deviant" from/ incomplete form of Standard British English. While the description and analysis of Sri Lankan English by scholars like Kandiah and Parakrama, have contributed much to legitimizing this variety, it appears that the examples (lexis, syntax and discourse) are predominantly from Sinhala bilingual use. Thus, though the specificities of educated Lankan English reflect the areas of common language contact between Sinhalese and Tamils, and may therefore be appropriate to middle and upper class bilingual usage, they appear to exclude and thereby marginalize under-elass and rural Tamils. As long as the Sinhala user of English remains the 'standard-bearer' of Lankan English, there will be (and have been) negative implications on the acceptance of under-elass Tamil usage. The markers for such "non-acceptance" (or a deliberate refusal to accept) appear predominantly in one's pronunciation and varying grammatical constructions. Building on a presentation at the SLELTA Conference (2006), this paper seeks to provide examples of how the norms and standards of Lankan English, as well as vestigial Standard English value systems, tend to discriminate against, and pathologies under-class Tamil usage. In addition, it will seek to demonstrate how, in an already (ethnically) charged environment, these "errors" become more than simply markers of class and caste, but of ethnicity; and this has serious implications, in today's Sri Lankan context.
Buddidst affiliation at Sigiriya
(University of Peradeniya, Sri Lanka, 2006-11-30) Somathilake, Mahinda
According to the Brahmi inscriptions on the western side of Sigiriya, it is obvious that there was a population of monks at the foot of the rock as early as first or second century BC. But Sigiriya came to be better known during the reign of the parricide king Kassapa who shifted his capital from Anuradhapura to Sigiriya. Moggallana I, the successor, having regained the throne once again shifted his capital to Anuradhapura and the palace on the rock of Sigiriya was converted into a monastery and offered to the Buddhist monks. The Buddhist order itself had no great love for the place; for it is not mentioned afterwards as having had anything to do with religion though the chronicle states that the Pabbatavihara built by Moggallana was granted to Mahanama thero. Although it is not possible to say precisely how long these later monasteries continued to exist in Sigiriya, there is no doubt that these monasteries continued to function even during subsequent periods, since one inscription from Abhayagiriya most probably belonging to the tenth century AD mentions Sihagiri maha sä. This is further substantiated by the fact that the recent excavations at Sigiriya have also revealed a series of developments extending from the third and second centuries BC to the twelfth and thirteenth centuries AD at the site. Besides, periodic extensions of drip-ledges and deepening of rock shelters, successive layers of plaster and paintings and at least five or six re-constructions of the walled extensions and the internal partitions indicate that Sigiriya had been used even in later times. In addition to the paintings on the main rock, a number of caves at the foot of the rock also contained paintings. Some of these caves carry several layers of paintings on the canopies and it is quite possible that the bottom layers of paintings on these are contemporary with the time when religious recluses first made their abode in the caves. The ceiling paintings at the Cobra-hood cave at Sigiriya proves that the cave was used as a Buddhist shrine and the Asana cave also contains painted fragment of a scene of which one panel depicts a worshipping scene. These figures in the cave strongly suggest that an image of the Buddha was placed on the existing throne. It seems that their fragmentary nature and unusually dramatic location have led to the Sigiriya paintings being interpreted in a number of ways. It is also evident that these expressions of various interpretations are mainly due to the lack of information. Accordingly, considerable speculation has helped to advance a few major theories in the attempt to find a solution. Of these, the most popular one that prevails at present is that these paintings depict some apsaras. It is not only the simplest but also the most logical and acceptable interpretation, especially since they are shown among and half hidden by clouds in the sky. It is believed that they depict some goddesses from Tusita heaven and it signifies Buddhist ideology to a great extent. It is thus obvious that except for a short reign of Kassapa who created secular buildings there, the Buddhist religious nature, would have been predominant in the Sigiriya area for a very long period. All these facts silently reveal a very close Buddhist affiliation at the site.
Blood Pressure and Heart Rate Variability in response to a surgical stimulus under gueneral anesthesia among adult female patients: A preliminary report
(University of Peradeniya, Sri Lanka, 2006-11-30) Jayasinghe, E. H. K.; Dharmapal, H. L. P. S.; Kumarasiri, P. V. R.; Goonasekera, C. D. A.
Blood pressure changes and heart rate variability are due to complex interactions between external stimuli and mechanisms of cardiovascular control. While blood pressure changes strongly correlate with target organ damage; variable heart rate is a powerful predictor of arrhythmia related complications in patients surviving the acute phase of myocardial infarction. Nevertheless, reports on the assessment of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) variations in response to a surgical stimulus under the conditions of general anaesthesia are not available in the literature. This study therefore, aims to assess changes in SBP, DBP and HR following an initial standard surgical stimulus such as skin incision, among adult, female patients during general anaesthesia. The relationship between these changes and the preoperative cardiovascular status is also analysed . Standard mercury sphygmomanometre was used to obtain blood pressure. The pulse rate was calculated manually. Baseline measurements were taken the day before surgery. Test measurements were taken in the theatre during surgery. The DBP and SBP increased between the second and fourth minute after the skin incision. However, between the fourth and eighth minute the SBP decreased whereas, the DBP increased from the fourth to the sixth minute and thereafter declined between the sixth and eighth minute. In the case of HR, an increase was observed before induction of anaesthesia as compared with baseline readings. It continued to increase even after induction and then two minutes after the skin incision it began to decrease. This trend continued and remained so for the next eight minutes, with minor variations. These observations suggest that baseline SBP and DBP are predictive of SBP and DBP changes before induction of anaesthesia and the initial eight minutes after surgical skin incision. However, baseline HR does not provide a good predictive value of HR during the initial eight minutes after surgical skin incision.

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