Judul: Konstruksi Skema Pembagian Rahasia Asmuth Bloom yang Diterapkan pada Algoritme ElGamal
Abstrak: Kegiatan bertukar informasi merupakan hal yang sudah biasa dilakukan banyak orang dari berbagai latar belakang di zaman modern ini. Namun dalam aplikasinya, masalah keamanan dan juga kepemilikan bersama informasi menjadi suatu risiko bagi pihak yang melakukan pertukaran informasi. Secret sharing merupakan salah satu metode untuk mengamankan suatu rahasia dengan membagi atau mendistribusikan rahasia menjadi beberapa serpihan. Secret sharing digunakan untuk perlindungan terhadap ancaman kehilangan kunci kriptografi. Karya ilmiah ini membahas tentang penerapan skema pembagian rahasia Asmuth Bloom pada algoritme ElGamal. Algoritme ElGamal terdiri dari tiga proses, yaitu proses pembentukan kunci, proses enkripsi yang mengubah pesan bermakna menjadi pesan sandi, dan proses dekripsi yang mengembalikan pesan bersandi menjadi pesan bermakna.
Keyword: Kriptografi, Secret Sharing, Asmuth Bloom, Algoritme ElGamal, Enkripsi, Dekripsi

Judul: Protokol Pertukaran Kunci Berbasis Kriptosistem Kunci Publik Elgamal.
Abstrak: Komunikasi atau pertukaran data sekarang ini sangat mudah dilakukan bahkan komunikasi jarak jauh sekalipun. Namun kemudahan ini tidak hanya membawa dampak positif tetapi juga negatif, salah satunya adalah keamanan datadata yang dipertukarkan tersebut. Data tersebut harus dienkripsi menjadi pesan rahasia agar tidak seorang pun, selain party yang berkomunikasi, dapat mengetahui isi pesan rahasia tersebut. Kriptosistem pertukaran kunci publik ElGamal merupakan salah satu metode yang dapat digunakan untuk pengamanan tersebut. Karya ilmiah ini menjelaskan teori-teori yang digunakan dalam protokol pertukaran kunci berbasis kriptosistem kunci publik ElGamal, mekanisme protokol tersebut dan menganalisis keamanan dari kriptosistem kunci publik ElGamal. Party-party yang berkomunikasi akan membuat sebuah kunci rahasia atau kunci sesi dengan pertukaran kunci publik. Setelah pertukaran tersebut, party-party akan memeroleh kunci rahasia atau kunci sesi yang akan digunakan untuk mengenkripsi dan dekripsi data. Kriptosistem kunci publik ElGamal dapat dikatakan cukup aman karena adanya masalah logaritma diskret dan proses autentikasi yang mencegah terjadinya man-in-the-middle attack.
Keyword: ElGamal, komunikasi, kriptosistem, kunci rahasia

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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