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All Journal Seminar Nasional Aplikasi Teknologi Informasi (SNATI) Semantik Jurnal Teknologi Informasi dan Ilmu Komputer Seminar Nasional Informatika (SEMNASIF) JOIV : International Journal on Informatics Visualization Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) JURNAL MEDIA INFORMATIKA BUDIDARMA JURNAL TEKNIK INFORMATIKA DAN SISTEM INFORMASI JURIKOM (Jurnal Riset Komputer) Aptisi Transactions on Technopreneurship (ATT) Building of Informatics, Technology and Science Journal Sensi: Strategic of Education in Information System Jurnal Sistem Komputer dan Informatika (JSON) Aiti: Jurnal Teknologi Informasi Jurnal Indonesia : Manajemen Informatika dan Komunikasi Jurnal Ilmiah Sains Magistrorum et Scholarium: Jurnal Pengabdian Masyarakat IT-Explore: Jurnal Penerapan Teknologi Informasi dan Komunikasi Jurnal Indonesia : Manajemen Informatika dan Komunikasi Jurnal DIMASTIK

Theopillus J. H. Wellem

Universitas Kristen Satya Wacana

Author-ID : 403010

Agriculture, Biological Sciences & Forestry Humanities Biochemistry, Genetics & Molecular Biology Chemistry Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Economics, Econometrics & Finance Education Electrical & Electronics Engineering Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Library & Information Science Mathematics Physics Social Sciences Other

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Implementasi Sistem Otentikasi Dokumen Berbasis Quick Response (QR) Code dan Digital Signature Antika Lorien; Theophilus Wellem
Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) Vol 5 No 4 (2021): Agustus 2021
Publisher : Ikatan Ahli Informatika Indonesia (IAII)

The authenticity and integrity of documents are essential in data exchange and communication. Digital documents must be verifiable for their authenticity and integrity by all parties that use the documents. Generally, digital documents can be authenticated by using digital signatures. This study aims to implement a document authentication system based on Quick Response (QR) code and digital signature. As the case study, the document authentication system is implemented to generate digital signatures for student’s certificate documents. Furthermore, the system can also verify the authenticity of the certificate documents. Creating a digital signature requires a hash function algorithm for generating the message digest of the document. In addition, an algorithm to generate the public key and the private key used in the encryption/decryption of the message digest is also needed. The hash function utilized in this study is the Secure Hash Algorithm-256 (SHA-256), while the algorithm used for encryption/decryption is the Rivest-Shamir-Adleman (RSA) algorithm. The system is evaluated by verifying 30 student certificate documents, of which 15 of them were certificates with QR code signature generated by the system and the other 15 were certificates with QR code signature generated using a random QR code generator. The system’s testing results demonstrate that the system can ensure the authenticity and integrity of the signed certificate documents to prevent document falsification. All documents that contain random QR codes were correctly identified as false documents.

Implementasi BGP dan Resource Public Key Infrastructure menggunakan BIRD untuk Keamanan Routing Valen Brata Pranaya; Theophilus Wellem
Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) Vol 5 No 6 (2021): Desember 2021
Publisher : Ikatan Ahli Informatika Indonesia (IAII)

The validity of the routing advertisements sent by one router to another is essential for Internet connectivity. To perform routing exchanges between Autonomous Systems (AS) on the Internet, a protocol known as the Border Gateway Protocol (BGP) is used. One of the most common attacks on routers running BGP is prefix hijacking. This attack aims to disrupt connections between AS and divert routing to destinations that are not appropriate for crimes, such as fraud and data breach. One of the methods developed to prevent prefix hijacking is the Resource Public Key Infrastructure (RPKI). RPKI is a public key infrastructure (PKI) developed for BGP routing security on the Internet and can be used by routers to validate routing advertisements sent by their BGP peers. RPKI utilizes a digital certificate issued by the Certification Authority (CA) to validate the subnet in a routing advertisement. This study aims to implement BGP and RPKI using the Bird Internet Routing Daemon (BIRD). Simulation and implementation are carried out using the GNS3 simulator and a server that acts as the RPKI validator. Experiments were conducted using 4 AS, 7 routers, 1 server for BIRD, and 1 server for validators, and there were 26 invalid or unknown subnets advertised by 2 routers in the simulated topology. The experiment results show that the router can successfully validated the routing advertisement received from its BGP peer using RPKI. All invalid and unknown subnets are not forwarded to other routers in the AS where they are located such that route hijacking is prevented.

Optimizing Multilayer Perceptron with Cost-Sensitive Learning for Addressing Class Imbalance in Credit Card Fraud Detection Priatna, Wowon; Hindriyanto Dwi Purnomo; Ade Iriani; Irwan Sembiring; Theophilus Wellem
Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) Vol 8 No 4 (2024): August 2024
Publisher : Ikatan Ahli Informatika Indonesia (IAII)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29207/resti.v8i4.5917

The increasing use of credit cards in global financial transactions offers significant convenience for consumers and businesses. However, credit card fraud remains a major challenge due to its potential to cause substantial financial losses. Detecting credit card fraud is a top priority, but the primary challenge lies in class imbalance, where fraudulent transactions are significantly fewer than non-fraudulent ones. This imbalance often leads to machine learning algorithms overlooking fraudulent transactions, resulting in suboptimal performance. This study aims to enhance the performance of Multilayer Perceptron (MLP) in addressing class imbalance by employing cost-sensitive learning strategies. The research utilizes a credit card transaction dataset obtained from Kaggle, with additional validation using an e-commerce transaction dataset to strengthen the robustness of the findings. The dataset undergoes preprocessing with RUS and SMOTE techniques to balance the data before comparing the performance of baseline MLP models to those optimized with cost-sensitive learning. Evaluation metrics such as accuracy, recall, F1 score, and AUC indicate that the optimized MLP model significantly outperforms the baseline, achieving an AUC of 0.99 and a recall of 0.6. The model's superior performance is further validated through statistical tests, including Friedman and T-tests. These results underscore the practical implications of implementing cost-sensitive learning in MLPs, highlighting its potential to significantly enhance fraud detection accuracy and offer substantial benefits to financial institutions.

Co-Authors Ade Iriani Adi Setiawan Adriyanto Juliastomo Gundo Agustinus Fritz Wijaya Antika Lorien Anton Hermawan Arthur, Christian Atik Setyanti, Angela Bentar Priyopradono Danang Maulana Ikhsan Daniawan, Benny Daniel D Kameo Danny Manongga Darmawan Utomo Donny Priyadi Edi Suharyadi Erwien Christianto Fauzan, Rafi Ardhan Fra Arsandy Kusuma Sejati Fransiscus Bryan Prasetio Gabriel Gracia Salindeho Hanita Yulia Henderi . Hendry Hendry . Hindriyanto Dwi Purnomo Ignatius Agus Supriyono Ikhsan, Danang Maulana Ilham Hizbuloh Imanuel Susanto Indrastanti Ratna Widiasari Irwan Sembiring Ivanna Kristianti Timotius Iwan Setyawan Jonathan Putera Perdana Juliastomo Gundo, Adriyanto Krismiyati krismiyati krismiyati Kristoko Dwi Hartomo Lasso, Aldi Luis Geraldo Mauboy Maulana, Aldias Henry Muhamad Yusup Pantow, Prayogo Pangestu Piter Wijaya Prakoso, Alvian Dafa Priatna , Wowon Putra, Yeheskiel Mandala Rafi Ardhan Fauzan Rafly Fernanda Rizky Restu Fauzi Roland Tumbelaka Palar Sri Yulianto Joko Prasetyo Suharyadi Sutarto Wijono Tintien Koerniawati Valen Brata Pranaya Wahab, Nur Haliza Abdul Weku, Winsy C.D Yeheskiel Mandala Putra Yessica Nataliani Yonas Juniantiko Putro

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