Judul: Implementasi dan Analisis Steganografi Audio Menggunakan Discrete Cosine Transform (DCT)
Abstrak: The rapid development of the internet and the digital information revolution caused significant changes in the global society, ranging from the influence on the world economy to the way people communicate. Digital communication strongly supports the ease of message exchange transactions, but on the other hand has a risk of security, especially for confidential messages. This research proposed implementation of steganography audio in WAV files transformed using DCT. The results of DCT coefficients are divided into an arbitrary number of segments and the energy of each segment is calculated. Text message are then embedded into the selected peaks of the highest energy segment with values ranging peaks from -0.4 – 0.4. Recovery text message from Stego-audio are extracted by performing the inverse operation of steganography embedding process. Simulation results indicate that a selected steganography technique meet the primary criteria of imperceptibility and recovery. In addition, the result of Signal-to-Noise Ratio (SNR) values range from 12dB – 40dB. The test quality of stego-audio makes use of objective and subjective analysis. The objective analysis uses Euclidean distance and the subjective analysis is based on survey
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Judul: Penerapan dan Analisis Metode Discrete Cosine Transform (DCT) dengan Huffman Code pada Steganografi Video AVI
Abstrak: The use of digital data is increasingly encountered and began to replace analog media's role in various applications. Digital data has several advantages such as being easy in storage, duplication, processing, and distribution. Digital communication on the one hand strongly support the ease of message exchange transactions, but on the other hand has a higher risk of security, especially for confidential messages. Steganographic methods are used to hide secret messages in digital form into other digital media. This research proposed the implementation of steganography in AVI video using the Discrete Cosine Transform (DCT) technique. DCT is a method that will transform data from the spatial domain into the frequency domain and separates the data into two parts, namely the DC coefficient and AC coefficients. DCT-based steganography embed the text message in Least Significant Bits (LSB) of the DC coefficient. The test consists of subjective video quality analysis based on survey and objective testing using the Mean Structure Similarity (MSSIM), analysis of the data hiding validity, and the level of data hiding capacity. Huffman compression on the text is used to increase the capacity of the storage. In addition, using more bits of DC coefficients will further increase the capacity. The test result shows that the steganographic technique using DCT produces data hiding with level the of validity reaches 100%. In addition, the quality of the resulting video is still relatively good up to 4-LSB for message insertion. Also, it is known that the Huffman compression on the text message can reduce the processing time and increase the capacity of the insertion.
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Judul: Revisi marga Ptychopyxis miquel (Euphorbiaceae) di kawasan Malesia
Abstrak: Ptychopyxis adalah salah satu marga dari 317 marga yang termasuk ke dalam suku Euphorbiaceae. pertama kali dipublikasikan oleh Miquel (1860). Marga ini Marga ini pernah dimasukkan kedalam marga lain, yaitu Podadenia, Mallotus dan Clarorivinia. Fakta tersebut menunjukkan bahwa batasan marga Ptychopyxis belum cukup mantap. Persebaran marga ini menurut Van Welzen (1993) jumpai di Thailand, Indochina dan kawasan Malesia, di seluruhnya ada 23 jenis dan 10 jenis diantaranya terdapat di kawasan Malesia. Marga ini umum berperawakan pohon dan berumah dua, tumbuh di hutan hujan dataran rendah sampai pada ketinggian 1500 m dpl. Penelitian taksonomi yang komprehensif tentang marga ini telah dilakukan oleh Airy Shaw pada tahun 1960; sejak saat itu belum ada penelitian taksonomi yang lebih kompre- hensif, khususnya untuk kawasan Malesia. Kini dengan bertambahnya jumlah spesimen koleksi baru, maka tepatlah kiranya dilakukan revisi marga. Tujuan penelitian ini adalah untuk memberikan batasan marga serta jenis-jenisnya yang termasuk dalam Ptychopyxis selain itu diteliti pula hubungan kekerabatan antar jenis dan keterangan-keterangan..dst
Keyword: Herbarium Bogoriense, Podadenia, Mallotus, Clarorivinia