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Increasing The Capacity of Headstega Based on Bitwise Operation Hasmawati Hasmawati; Ari Moesriami Barmawi
Jurnal Ilmu Komputer dan Informasi Vol 14, No 2 (2021): Jurnal Ilmu Komputer dan Informasi (Journal of Computer Science and Information
Publisher : Faculty of Computer Science - Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21609/jiki.v14i2.957

Abstract

Headstega (Head steganography) is a noiseless steganography that used email headers as a cover for concealing messages. However, it has less embedding capacity and it raises suspicion. For overcoming the problem, bitwise operation is proposed.  In the proposed method, the message was embedded into the cover by converting the message and the cover into binary representation based on a mapping table that was already known by the sender and the receiver. Furthermore, XOR bitwise operations were applied to the secret message and cover bits based on random numbers that were generated using a modular function. Moreover, the result was converted into characters that represent the secret message bits. After embedding the message into the cover, an email alias was generated to camouflage the secret message characters. Finally, the sender sends the embedded cover and the email alias to the recipient. Using the proposed method, the embedding capacity is 89% larger than using the original Headstega. For reducing the adversary’s suspicion, the existing email address was used instead of creating a new email address.
Modifikasi Headstega berdasarkan Penyisipan Karakter Hasmawati Hasmawati; Ari Moesriami Barmawi
Indonesia Journal on Computing (Indo-JC) Vol. 2 No. 1 (2017): Maret, 2017
Publisher : School of Computing, Telkom University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21108/INDOJC.2017.2.1.145

Abstract

AbstractHead steganography or Headstega is one of noiseless steganography paradigm, or Nostega.This method utilizes the email header as a media of  message concealment. There are several problems that can be enhanced in Headstega, i.e. low embedding capacity and high level of suspicion. Modified Headstega based on Character Hiding uses a combination of consonant vowel to embed the secret messages into email address. The messages embedding process using four consonant vowel combination that represented one character in Indonesian language.  From the experiments conducted, the results obtained that the Modified Headstega has a better performance than the Original Headstega in term of embedding capacity and also in suspicion level. Keyword : Steganography, Nostega, Headstega, Character Hiding
Grid-based Image Encryption using Code-based Cryptography Dian Anggoro Putro Bhagaskoro; Ari Moesriami Barmawi
Indonesia Journal on Computing (Indo-JC) Vol. 5 No. 3 (2020): December, 2020
Publisher : School of Computing, Telkom University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34818/INDOJC.2020.5.3.493

Abstract

Recently, image is frequently sent or exchanged electronically, such that image security is important. A method for securing images is using RSA. However, RSA needs more time for securing an image. For overcoming the RSA problem, McEliece Cryptosystem is introduced to grid-based image encryption. The image is divided into blocks and each block is divided into grids, then finally McEliece Cryptosystem is applied to the pixels in the grids. Based on the experiment’s result, it was proven that the execution time of the proposed method is less than the previous one, while maintaining the security. Keywords: McEliece Cryptosystem, RSA, Image Encryption, Image Decryption, Grid 
Column-Level Database Encryption Using Rijndael Algorithm and Dynamic Key on Learning Management System Ariva Syam Mursalat; Ari Moesriami Barmawi; Prasti Eko Yunanto
Indonesia Journal on Computing (Indo-JC) Vol. 7 No. 1 (2022): April, 2022
Publisher : School of Computing, Telkom University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34818/INDOJC.2022.7.1.609

Abstract

The course management system’s goal is to help learning activities. The system helps tomanage tasks, the grading process, and user communications. To avoid unauthorized dataaccess, the course management system needs a mechanism to protect the password that isused in the system’s login process. Database encryption using Rijndael algorithm is proposedby Francis Onodueze et al. to protect the data. A key is needed for the encryption process,and the key has to be kept secret. Thus, when the key is static, it is vulnerable against keyguessing attacks. To overcome the static key’s drawback, a dynamic key generation usingHash Messages Authentication Code - Deterministic Random Bit Generator (HMAC-DRBG)is proposed because it can generate keys periodically. Based on the evaluation, the probabilityof success key guessing attack using the proposed method is less than using the previousmethod, while the time complexity of those methods is similar.
Overcoming Alignment Problem in Non-Identical Mathematical Support Visual Cryptography Schemes Ari Moesriami Barmawi; Widhian Bramantya
Journal of ICT Research and Applications Vol. 12 No. 1 (2018)
Publisher : LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.ict.res.appl.2018.12.1.6

Abstract

An important problem in visual cryptography is the alignment problem. Although Liu, et al. have proposed a method for aligning the shares, there is still a problem with the non-identical mathematical support visual cryptography schemes. For overcoming this problem, the Three-Orthogonal-Point (3OP) method is proposed in this paper. Based on the experimental result it was proven that it can overcome the alignment problem, while the time complexity for aligning the shares is decreased significantly from O((m×A)2) to O(m×AI), for AI < A. The security is maintained, since an attacker cannot obtain any information related to the secret image.
Paraphrasing Method Based on Contextual Synonym Substitution Ari Moesriami Barmawi; Ali Muhammad
Journal of ICT Research and Applications Vol. 13 No. 3 (2019)
Publisher : LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.ict.res.appl.2019.13.3.6

Abstract

Generating paraphrases is an important component of natural language processing and generation. There are sev­eral applications that use paraphrasing, for example linguistic steganography, recommender systems, machine translation, etc. One method for paraphrasing sentences is by using synonym substitution, such as the NGM-based paraphrasing method proposed by Gadag et al. The weakness of this method is that ambiguous meanings frequently occur because the paraphrasing process is based solely on n-gram. This negatively affects the naturalness of the paraphrased sentences. For overcoming this problem, a contextual synonym substitution method is proposed, which aims to increase the naturalness of the paraphrased sentences. Using the proposed method, the paraphrasing process is not only based on n-gram but also on the context of the sentence such that the naturalness is increased. Based on the experimental result, the sentences generated using the proposed method had higher naturalness than the sentences generated using the original method.
Bimodal Keystroke Dynamics-Based Authentication for Mobile Application Using Anagram Prasti Eko Yunanto; Ari Moesriami Barmawi
Jurnal Ilmu Komputer dan Informasi Vol. 15 No. 2 (2022): Jurnal Ilmu Komputer dan Informasi (Journal of Computer Science and Informatio
Publisher : Faculty of Computer Science - Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21609/jiki.v15i2.1015

Abstract

Currently, most of the smartphones recognize uses based on static biometrics, such as face and fingerprint. However, those traits were vulnerable against spoofing attack. For overcoming this problem, dynamic biometrics like the keystroke and gaze are introduced since it is more resistant against spoofing attack. This research focuses on keystroke dynamics for strengthening the user recognition system against spoofing attacks. For recognizing a user, the user keystrokes feature used in the login process is compared with keystroke features stored in the keystroke features database. For evaluating the accuracy of the proposed system, words generated based on the Indonesian anagram are used. Furthermore, for conducting the experiment, 34 participants were asked to type a set of words using the smartphone keyboard. Then, each user’s keystroke is recorded. The keystroke dynamic feature consists of latency and digraph which are extracted from the record. According to the experiment result, the error of the proposed method is decreased by 23.075% of EER with FAR and FRR are decreased by 16.381% and 10.41% respectively, compared with Kim’s method. It means that the proposed method is successful increase the biometrics performance by reducing the error rates
Strengthening INORMALS Using Context-based Natural Language Generation Soni Yora; Ari Moesriami Barmawi
Journal of ICT Research and Applications Vol. 16 No. 2 (2022)
Publisher : LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.ict.res.appl.2022.16.2.1

Abstract

The noiseless steganography method that has been proposed by Wibowo can embed up to six characters in the provided cover text, but more than 59% of Indonesian words have a length of more than six characters, so there is room to improve Wibowo’s method. This paper proposes an improvement of Wibowo’s method by modifying the shifting codes and using context-based language generation. Based on 300 test messages, 99% of messages with more than six characters could be embedded by the proposed method, while using Wibowo’s method this was only 34%. Wibowo’s method can embed more than six characters only if the number of shifting codes is less than three, while the proposed method can embed more than six characters even if there are more than three shifting codes. Furthermore, the security for representing the number of code digits is increased by introducing a private key with the probability of guessing less than 1, while in Wibowo’s method this is 1. The naturalness of the cover sentences generated by the proposed method was maintained, which was about 99% when using the proposed method, while it was 98.61% when using Wibowo’s method.
List Steganography Based On Syllable Patterns David Martin; Ari Moesriami Barmawi
eProceedings of Engineering Vol 2, No 2 (2015): Agustus, 2015
Publisher : eProceedings of Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Abstract—List-based steganography or Listega is a steganography methodology with noiseless steganography paradigm, or Nostega. In this methodology, a message is embedded in the first characters of list items to create a list- cover. Listega uses filtered cover, which contains only the embedded list items. There are some rooms of improvements in Listega due to several problems, i.e. small embedding capacity and embedding failure in using several index of Latin square that it uses as mapping method. The proposed method uses syllable patterns of Indonesian language as a method of embedding message using Employee Birthday List. It also introduces an algorithm to make an unfiltered list-cover, which contains the embedded and non-embedded list items. This algorithm also makes possible to provide a grouping and a degree of sorting of list-covers. Furthermore, the results of the experiments show that the proposed method has higher capacity compares to Listega in filtered cover conditions. The use of unfiltered cover also reduces the suspicion from other parties. Keywords—Listega; Noiseless; steganography; syllable patterns
Securing KTP Data Using QR Code Modification and Elliptic Curve Cryptography Rakha Aditya Nugraha; Ari Moesriami Barmawi
Indonesia Journal on Computing (Indo-JC) Vol. 9 No. 1 (2024): April, 2024
Publisher : School of Computing, Telkom University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34818/INDOJC.2024.9.1.909

Abstract

Identity Cards (KTP) are essential for Indonesian people. KTP contains personal information, such as National Identity Number (NIK), Name, Address, Gender, etc. Since KTP has essential data and is still printed conventionally, there is a vulnerability if the KTP is lost, and the owner's data is disclosed so that if an irresponsible person finds it, the data can be used for impersonating the owner. In the previous method proposed by Haque et al., [1], the data was stored in a QR Code. However, there was no verification method to legitimize the original owner, and the system did not have a login feature. To overcome the weakness of Haque et al., method [1], the owner's NIK is encrypted using the Elliptic Curve El-Gamal (ECEG) and further signed using ECDSA by the owners before storing it in the QR Code. For obtaining the owner's data in the database, the verification process should be done after the QR Code is scanned. Using the proposed method, the probability of success for a guessing attack is 1 / (n-1). Meanwhile, the probability of success for an impersonation attack is 1 / (q1 * q2 * l).