Judul: Modifikasi Algoritme Fungsi Hash Md5 Didasarkan Pada Analisis Syarat Cukup Serangan Diferensial
Abstrak: Salah satu primitif kriptografi modern adalah fungsi hash kriptografi, atau sering disebut fungsi hash satu-arah. Dari segi transformasinya, fungsi hash didefinisikan sebagai fungsi yang memetakan bitstring dengan panjang sebarang ke bitstring dengan panjang tetap. Output dari fungsi hash adalah nilai hash (hash value). Di samping itu, dari segi peranannya di dalam kriptografi, fungsi ini juga diharuskan memenuhi sifat satu arah dan tahan tumbukan. Fungsi hash h dikatakan bersifat satu arah apabila secara komputasi tak layak menentukan input x jika diketahui nilai hash y sehingga y = h(x). Di lain pihak, sifat tahan tumbukan dari h dimaknai secara komputasi tak layak menentukan pasangan input x dan x’ dengan x ≠ x’ sehingga outputnya sama, h(x) = h(x’) (terjadi tumbukan). Sifat satu arah dan tahan tumbukan menyebabkan fungsi hash salah satunya digunakan untuk melindungi integritas data dari pemalsuan. Sebagai ilustrasi, suatu pesan x dilabelkan dengan nilai hashnya y = h(x). Kita bisa memalsukan x apabila kita bisa menentukan pesan lain x’ ≠ x sehingga h(x’) = y (mempunyai label yang sama dengan x). Jika ini yang terjadi maka fungsi hash yang bersangkutan dikatakan tidak aman, dengan kata lain x’ bisa digunakan untuk memalsukan x.
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Judul: Implementasi Fungsi Hash MD6 untuk Integritas Ijazah Digital
Abstrak: Nowadays certificates are still printed on papers, which makes it possible to forge by irresponsible parties. Certificates which are still printed on paper may also suffer from loss of important information when the document is lostor damaged. These issues motivates the needs for digital certificates, other than the fact that there are easier to store. However digital certificates face the risk of being abused: modified or duplicated. Protection against digital certificates is necessary to avoid these abuses. One of the cryptographic technique used to ensure data integrity is hash function. This research used an algorithm called MD6, which is improvement of MD5 algorithm avoiding collision that had been found in MD5. In this research, the MD6 algorithm is implemented sequentially and uses two optional operators, the length (d) and the key (K). The MD6 hash function convert the digital certificates into a series of message digest which will be the references of integrity verification from a digital certificates. The digital certificates which has been modified will produce different message digest when compared with the message digest of the original certificates. The MD6 algorithm be able to avoid collision.
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Judul: Habitat characteristics of timor friarbird philemon inornatus in Camplong Landscape Kupang District, East Nusa Tenggara
Abstrak: Timor Friarbird (Philemon inornatus, G. R. Gray, 1846) is one of the six endemic birds of Timor and is a protected species. The population of bird is suspected to have been decreasing over the past six years along with the decreasing of the quantity and quality of physical and biotic factors of its habitat. Knowledge on landscape spatial pattern could be used to evaluate the quantity and quality of habitat. This research aimed at identifying spatial habitat characteristics of Timor Friarbird based on dominant factors of physical and biotic habitat components. Principle Component Analysis (PCA) on the physical habitat factors showed that variables that have strong correlation with the presence of the bird were Normalized Difference Vegetation Index (NDVI), slope, distance from secondary forest, distance from bush, distance from cashew plantation, distance from crop plantation, and distance from roads. The biotic factors that have strong correlation with the presence of Timor Friarbird were the total number of plant species, number of plants used for food and cover, and mean height of trees. Height of poles was the only variable that has no correlation with the presence of Timor Friarbird. The most dominant physical and biotic factors that influent the presence of Timor Friarbird at a site are the density of foraging trees, slope, distance from the river, the distance from secondary forest, the density of cover pole and the distance from road. The estimation population of Timor Friarbird in Camplong region is low; this might be caused by low feeding tree density, high rates of poaching, the uneven distribution of feed vegetation and the flowering season, habitat degradation due to illegal logging, grazing cattle in the wild, and invasion of siam weed or chromolaena (Chromolaena odorata). The results of land cover classification at Camplong region based on Landsat_5 Thematic Mapper (TM) image with ArcGIS 9.3 and Erdas 9.1 obtained 11 land cover classes, with shrub as the dominant class. Keyword: Philemon inornatus, Habitat Spatial Characteristics, PCA, Population, Land Cover
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