Judul: Model Pengelolaan Berkelanjutan Kawasan Taman Wisata Alam Sumber Semen di Kabupaten Rembang
Abstrak: Sumber Semen Natural Tourism Park is the only conservation area located in Rembang Regency. This area is designated as a protected area by two ministries, namely the Ministry of Environment and Forestry and the Ministry of Energy and Mineral Resources. Confirmed by Presidential Decree Number 26 of 2011 concerning Designation of Groundwater Basins as Conservation/Protected Areas. One of the reasons is that this area is the largest water recharge area in Rembang Regency which is part of the North Kendeng Karst Mountains area. However, some parties are not aware of the value possessed by Sumber Semen Natural Tourism Park so that the willingness to participate in managing the area is still low. This study aims to estimate the total economic value of the area, determine the level of community dependence, determine the status of sustainable management of the area and develop a model for sustainable management of the Sumber Semen Natural Tourism Park area. This research is expected to be taken into consideration for stakeholders in making decisions related to Sumber Semen Natural Tourism Park, either directly or indirectly. This research was conducted at Sumber Semen Natural Tourism Park, Gading Village and Tahunan Village in 2021. The respondents used were 2% of the respondent population, both visitors and the research village community. Data collection was carried out by interviews, field observations, biodiversity exploration and literature study. Then analyzed by benefit transfer, willingness to pay and total economic value to estimate the total economic value of the area, analysis of economic benefits (share and cover) to determine the level of community dependence on the area, and sustainability analysis to determine the area's sustainability status. All analysis results are taken into consideration in developing a sustainable management model for the Sumber Semen Natural Tourism Park area. The total economic value is estimated by identifying the potential in Sumber Semen Natural Tourism Park. The potential in question is the potential of flora, fauna, springs, environmental services and forest carbon stocks in the area. Exploration results showed a diversity of identified flora as many as 124 species. It was found that there were still many woody species, such as teak (Tectona grandis) and two types of mahogany (Swietenia mahagoni and Swietenia macrophylla). This sufficiently illustrates the history of Sumber Semen Natural Tourism Park which was formerly eco-tourism area managed by Perhutani KPH Kebonharjo. Fauna diversity identified 6 species of birds, 1 mammal, 2 herpetofauna and several butterflies. Utilization of water is carried out for tourism activities, agricultural irrigation and fulfillment of household clean water needs. Utilization is carried out by the surrounding community and PDAM Banyumili, Rembang Regency, to meet the clean water needs of 4 sub-districts in Rembang Regency. The minimum estimation result of forest carbon stocks is 468.31 tons/ha. The estimated total economic value of the area is IDR 12,486,219,121. This value is obtained from the direct use value in the form of tourism activities, agricultural irrigation and household clean water of IDR 7,961,788,620, the indirect use value of forest carbon stocks of IDR 164,596,754, the optional value of biodiversity of IDR 98,573,961 and
Keyword: community dependency level, economic valuation, environmental  services, sustainability status, sustainable management

Judul: Nilai dan Manfaat Ekonomi Pengembangan Taman Wisata Alam bagi Konservasi dan Masyarakat Sekitar (Studi Kasus Taman Wisata Alam Rimbo Panti, Kabupaten Pasaman, Sumatera Barat)
Abstrak: Rimbo Panti Natural Tourism Park which located in the Pasaman District (West Sumatera) is a recreational area specifically developed as a buffer zone for the Rimbo Panti Natural Reserve. The natural recreational park have several recreational attractions but most of them are openly accessible. The open access nature of the attraction has resulted in an under-valuation of the recreational natural resources. It also has a potential for attracting large number of visitors beyond carrying capacity of the park, which in turn will put the nature reserve in danger. Therefore, it is important to examine the economic value and benefit of the natural tourism park for the conservation of the natural reserve and the surrounding communities. The study employs the Travel Cost Method (TCM) and regression analysis to reality factors influencing demand for the Rimbo Panti Natural Tourism Park. Recreational segmentation and pricing according to visitor’s Willingness To Pay (WTP) are used to spread visitor’s concentration and raise conservation fund. The study find that the recreational economic value was IDR 7.02 billion. Factors that significantly influence the demand for Rimbo Panti Natural Tourism Park, ie: the distance of visitor’s home to the park, the length of visitor’s knowledge of the park, number of dependants, and age. The economic benefits of the park for surrounding communities include providing job opportunities and source of additional income. Guest house owner experienced the most significant incremental increase of their income, from IDR 4.5 million to IDR 8 million per month. Revenue from recreational visitors was the main income for the swimming pool keeper. The conservational benefit of market segmentation was the reduction in number of visitors implying a decreasing threat to sustainability of the nature reserve. The reduction in the number of visitors, in fact will increase the income of the recreational park. It is estimated that the introduction of the price segmentation would increase in the income of the recreational park from IDR 88.2 million to IDR 283.3 million per year, which can be allocated for financing the conservation of the natural reserve
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Judul: Algorithm Construction of HLI Hash Function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice