• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2003.12a
• /
• pp.399-405
• /
• 2003

A new type of signature scheme, called NTRUSign, based on solving the approximately closest vector problem in an NTRU lattice was proposed in［7］,［8］. However no security proof against chosen messages attack has been made for this scheme. In this paper, we show that NTRUSign signature scheme contains the weakness of malleability. From this, one can derive new valid signatures from any previous message-signature pair which means that NTRUSign is not secure against strongly existential forgery.

• Journal of Industrial Convergence
• /
• v.20 no.3
• /
• pp.41-46
• /
• 2022

This paper proposes a consumer-tailored solution to prevent the forgery and falsification of data by incorporating blockchain technology in the online and offline distribution of agricultural produce. The solution provides customized services to consumers based on an analysis of the data generated from the sales, distribution, and consumption of quality of the produce. It can also ensure the safety and credibility of the produce, and allow producers to identify consumption intent and the flow of distribution. Producers will be able to determine the flow of produce based on the data collected and thus tailor promotional efforts. This is expected to be the fourth industrial revolution in the agricultural produce distribution sector. Utilizing blockchain and big data technology to create integrated record management systems that combine multiple solutions will shape future technology trends. In addition, if eco-friendly certification is acknowledged as a valuable service and can be incorporated into the distribution process, this solution could become a one-stop distribution solution for agricultural produce.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.1103-1109
• /
• 2023

Today, as the number of audio files submitted as legal evidence increases with the proliferation of smartphones, the integrity of audio files has become an important issue. Accordingly, the purpose of this study is to explore whether the metadata and file structure of audio files recorded on Samsung smartphones can be manipulated to be identical to the original. This study was based on Samsung smartphones, the most widely used in Korea, and conducted experiments on the built-in voice recording app and the 'Easy Voice Recorder' app, which is the most popular recording app. Through the experiments of this study, it was proven that the metadata and file structure of audio files can be manipulated. Therefore, this study reveals that metadata and file structure analysis have limitations in proving the integrity when audio files are analyzed for adoption as legal evidence. They also argue for the need to develop new voice file forgery technology that does not rely on metadata and file structure analysis.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.9
• /
• pp.51-58
• /
• 2019

Temporal analysis is very useful and important for digital forensics for reconstructing the timeline of digital events. Forgery of a file's timestamp can lead to inconsistencies in the overall temporal relationship, making it difficult to analyze the timeline in reconstructing actions or events and the results of the analysis might not be reliable. The purpose of the timestamp change is to hide the data in a steganographic way, and the other purpose is for anti-forensics. In both cases, the time stamp change tools are requested to use. In this paper, we propose a classification method based on the behavior of the timestamp change tools. The timestamp change tools are categorized three types according to patterns of the changed timestamps after using the tools. By analyzing the changed timestamps, it can be decided what kind of tool is used. And we show that the three types of the patterns are closely related to API functions which are used to develop the tools.

• Journal of Internet Computing and Services
• /
• v.21 no.2
• /
• pp.81-90
• /
• 2020

The purpose of this study is to study how to apply block-chain technology to prevent data forgery and alteration in the defense sector of AI(Artificial intelligence). AI is a technology for predicting big data by clustering or classifying it by applying various machine learning methodologies, and military powers including the U.S. have reached the completion stage of technology. If data-based AI's data forgery and modulation occurs, the processing process of the data, even if it is perfect, could be the biggest enemy risk factor, and the falsification and modification of the data can be too easy in the form of hacking. Unexpected attacks could occur if data used by weaponized AI is hacked and manipulated by North Korea. Therefore, a technology that prevents data from being falsified and altered is essential for the use of AI. It is expected that data forgery prevention will solve the problem by applying block-chain, a technology that does not damage data, unless more than half of the connected computers agree, even if a single computer is hacked by a distributed storage of encrypted data as a function of seawater.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.2 s.34
• /
• pp.39-47
• /
• 2005

This paper proposes and analyzes the MAC(Message Authentication Code) algorithm that is used for the transition integrity and the entity authentication of message. The MAC algorithm uses the DES algorithm which has 64-bit block and 56-bit key and we compare the security according to 64-bit and 32-bit length of MAC value. Moreover, we use the SEED algorithm which has 128-bit block and 128-bit key and compare the security according to 128-bit and 64-bit length of MAC value. We analyze the security the forgery attack according to length of message and length of MAC value. this paper, a coarse-to-fine optical flow detection method is proposed. Provided that optical flow gives reliable approximation to two-dimensional image motion, it can be used to recover the three-dimensional motion. but usually to get the reliable optical flows are difficult. The proposed algorithm uses Horn's algorithm (or detecting initial optical flow, then Thin Plate Spline is introduced to warp a image frame of the initial optical flow to the next image frame. The optical flow for the warped image frame is again used iteratively until the mean square error between two image sequence frames is lowered. The proposed method is experimented for the real moving Picture image sequence. The proposed algorithm gives dense optical flow vectors.

• Journal of Korea Multimedia Society
• /
• v.24 no.4
• /
• pp.558-568
• /
• 2021

The digital image to be accepted as legal evidence, it is important to verify the authentication of the digital image. This study proposes a method of authenticating digital images through three steps of comparing the file structure of digital images taken with iPhone, analyzing the encoding information as well as media logs of the iPhone storing the digital images. For the experiment, digital image samples were acquired from nine iPhones through a camera application built into the iPhone. And the characteristics of file structure and media log were compared between digital images generated on the iPhone and digital images edited through a variety of image editing tools. As a result of examining those registered during the digital image creation process, it was confirmed that differences from the original characteristics occurred in file structure and media logs when manipulating digital images on the iPhone, and digital images take with the iPhone. In this way, it shows that it can prove its forensic authentication in iPhone.

• International Journal of Internet, Broadcasting and Communication
• /
• v.8 no.3
• /
• pp.50-57
• /
• 2016

In 2013, Li et al. proposed an improved smart card-based remote user password authentication scheme, and claimed that their scheme not only overcomes security weaknesses of the Chen et al.'s scheme but also is a more user friendly scheme compared with other schemes. In this paper, we analyze the security of Li et al.'s authentication scheme and we show that Li et al.'s authentication scheme is still insecure against the various attacks, such as the off-line password guessing attack, the forgery attack, and the session key generation attack etc. Also, we propose an improved scheme that can resist these security drawbacks of Li et al.'s authentication, even if the secret information stored in the smart card is revealed. As a result of security analysis, the improved scheme is relatively more secure against several attacks than other related schemes in terms of the security.

• Journal of information and communication convergence engineering
• /
• v.9 no.1
• /
• pp.95-99
• /
• 2011

Digital forensics is the emerging research field for determining digital forgeries. Key issues of the tampered images are to solve the problems for detecting the interpolation factor and the tampered regions. This paper describes a method to detect the interpolation factors and the forged maps using the differential method and fast Fourier transform(FFT) along the horizontal, vertical, and diagonal direction, respectively from digital filtered tampered images. The detection map can be used to find out interpolated regions from the tempered image. Experimental results demonstrate the proposed algorithm proves effective on several filtering images by adobe $Photoshop^{TM}$ and show a ratio of detecting the interpolated regions and factors from digital filtered composite images.

• Journal of Information Processing Systems
• /
• v.15 no.1
• /
• pp.169-180
• /
• 2019

Transmitting visual information over a broadcasting network is not only prone to a copyright violation but also is a forgery. Authenticating such information and protecting its authorship rights call for more advanced data encoding. To this end, electronic watermarking is often adopted to embed inscriptive signature in imaging data. Most existing watermarking methods while focusing on robustness against degradation remain lacking of measurement against security loophole in which the encrypting scheme once discovered may be recreated by an unauthorized party. This could reveal the underlying signature which may potentially be replaced or forged. This paper therefore proposes a novel digital watermarking scheme in temporal-frequency domain. Unlike other typical wavelet based watermarking, the proposed scheme employed the Lorenz chaotic map to specify embedding positions. Effectively making this is not only a formidable method to decrypt but also a stronger will against deterministic attacks. Simulation report herein highlights its strength to withstand spatial and frequent adulterations, e.g., lossy compression, filtering, zooming and noise.