• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.1-8
• /
• 2002

Digital image watermarking is a technique for the purpose of protecting the ownership of the image by embedding proprietary watermarks in a digital image. It is required for the digital image watermarking scheme to pursue the robustness against water marking attacks and the perceptual Invisibility more than usual in steganography area, to guarantee not a hidden watermarking algorithm but the publicity of water-marking algorithm details and hidden use of key, which can protect the unauthorized user access from detection. In this paper we propose a new copyright watermarking scheme, which is barred on one-way hash functions using ElGamal functions and modular operations. ElGamal functions are widely used in cryptographic systems. Our watermarking scheme is robust against LSB(least significant bit) attacks and gamma correction attack, and also perceptually invisible. We demonstrate the characteristics of our proposed watermarking scheme through experiments. It is necessary to proceed as the future work the algorithm of achieving at the same time both the pseudo-randomness for the steno-key generation and the asymmetric-key generation.

• Journal of Internet Computing and Services
• /
• v.5 no.3
• /
• pp.73-86
• /
• 2004

This paper presents a hybrid digital watermarking scheme for color images, We insert two watermarks in the DWT domain using spread-spectrum correlation-based watermarking in luminance component of the color image and in spatial domain using pixel-value substitution of blue channel of color image. The objectives of this paper are to have the watermark robust to common signal processing and to detect any changes on the watermarked image for tamper detection at the same time. This watermark scheme will have the robustness characteristic as typical in frequency domain watermark, and also ability to detect any changes on the image (tamper detection).

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.5
• /
• pp.1938-1962
• /
• 2015

Security of information during transmission is a major issue in this modern era. All of the communicating bodies want confidentiality, integrity, and authenticity of their secret information. Researchers have presented various schemes to cope with these Internet security issues. In this context, both steganography and cryptography can be used effectively. However, major limitation in the existing steganographic methods is the low-quality output stego images, which consequently results in the lack of security. To cope with these issues, we present an efficient method for RGB images based on gray level modification (GLM) and multi-level encryption (MLE). The secret key and secret data is encrypted using MLE algorithm before mapping it to the grey-levels of the cover image. Then, a transposition function is applied on cover image prior to data hiding. The usage of transpose, secret key, MLE, and GLM adds four different levels of security to the proposed algorithm, making it very difficult for a malicious user to extract the original secret information. The proposed method is evaluated both quantitatively and qualitatively. The experimental results, compared with several state-of-the-art algorithms, show that the proposed algorithm not only enhances the quality of stego images but also provides multiple levels of security, which can significantly misguide image steganalysis and makes the attack on this algorithm more challenging.

• KIPS Transactions on Computer and Communication Systems
• /
• v.6 no.2
• /
• pp.75-86
• /
• 2017

Docker, which is one of the various virtualization technology in server systems, is getting popular as it provides more lightweight environment for service operation than existing virtualization technology. It supports easy way of establishment, update, and migration of server environment with the help of image and container concept. As the adoption of docker technology increases, the attack motive for the server for the distribution of docker images and the incident case of attacking docker-based hosts would also increase. Therefore, the method and procedure of digital forensic investigation of docker-based host including the way to extract the filesystem of containers when docker daemon is inactive are presented in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.6A
• /
• pp.602-609
• /
• 2002

In this paper, we propose an robust invisible watermarking method using wavelet transform and singular value decomposition for the ownership protection. of images. For this method, after we decompose the original image in three level using wavelet transform, we use singular value decomposition based key depended watermark insertion method in the lowest band $LL_3.$ And we also watermark using DCT for extraction of watermark and verification of robustness. In the experiments, we found that it had a good quality and robustness in attack such as compression, image processing, geometric transformation and noises. Especially, we know that this method have very high extraction ratio against nose and JPEG compression. And Digimarc's method can not extract watermark in 80 percent compression ratio of JPEG, but the proposed method can extract well.

• Journal of the Optical Society of Korea
• /
• v.20 no.1
• /
• pp.42-54
• /
• 2016

A hybrid color and grayscale images encryption scheme based on the quaternion Hartley transform (QHT), the two-dimensional (2D) logistic map, the double random phase encoding (DRPE) in gyrator transform (GT) domain and the three-step phase-shifting interferometry (PSI) is presented. First, we propose a new color image processing tool termed as the quaternion Hartley transform, and we develop an efficient method to calculate the QHT of a quaternion matrix. In the presented encryption scheme, the original color and grayscale images are represented by quaternion algebra and processed holistically in a vector manner using QHT. To enhance the security level, a 2D logistic map-based scrambling technique is designed to permute the complex amplitude, which is formed by the components of the QHT-transformed original images. Subsequently, the scrambled data is encoded by the GT-based DRPE system. For the convenience of storage and transmission, the resulting encrypted signal is recorded as the real-valued interferograms using three-step PSI. The parameters of the scrambling method, the GT orders and the two random phase masks form the keys for decryption of the secret images. Simulation results demonstrate that the proposed scheme has high security level and certain robustness against data loss, noise disturbance and some attacks such as chosen plaintext attack.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.24 no.6
• /
• pp.1129-1138
• /
• 2014

CAPTCHA is a technique which distinguishes human and machine using what human can judge easily but machine can't. Though Text-based-CAPTCHA has been widely used and can be implemented easily, it is less security than other CAPTCHAs such as image-based, or audio-based CAPTCHAs. To enhance the security of text-based CAPTCHA, many techniques have been developed. One of them is making CAPTCHA recognized hard using complex background or noise. In this paper, we introduce how to apply convolution filtering effectively to attack CAPTCHA and actually analyze Naver's CAPTCHA which has been used for joining a cafe with this method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.177-181
• /
• 2001

This paper presents an strategy algorithm of a soccer robot. We simply classified strategy of soccer robot as attack and defense. We use DC-motor in our Soccer Robot. We use the vision system made by MIRO team of Kaist and Soty team for image processing. Host computer is made by Pentium III. The RF module is used for the communication between each robot and the host computer. Fuzzy logic is applied to the path planning of our robot. We improve strategy algorithm of soccer robot. Here we explain improvement of strategy algorithm and fault of the our soccer robot system.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.15-18
• /
• 2004

In this paper, it is implemented the monitoring system for TV advertisement using video watermark. The functions of an advertisement monitoring system are automatically monitoring for the time, length, and index of the on-air advertisement, saving the log data, and reporting the monitoring result. The performance of the video watermark used in this paper is tested for TV advertisement monitoring. This test includes LAB test and field test. LAB test is done in laboratory environment and field test in actually broadcasting environment. LAB test includes PSNR, distortion measure in image, and the watermark detection rate in the various attack environment such as AD/DA(analog to digital and digital to analog) conversion, noise addition, and MPEG compression The result of LAB test is good for the TV advertisement monitoring. KOBACO and SBS are participated in the field test. The watermark detection rate is 100% in both the real-time processing and the saved file processing. The average deviation of the watermark detection time is 0.2 second, which is good because the permissible average error is 0.5 second.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.1
• /
• pp.206-213
• /
• 2007

In this paper, The monitoring system for TV advertisement is implemented using video watermark. The functions of the advertisement monitoring system are monitoring the time, length, and index of the on-air advertisement, saving the log data, and reporting the monitoring result. The performance of the video watermark used in this paper is tested for TV advertisement monitoring. This test includes LAB test and field test. LAB test is done in laboratory environment and field test in actually broadcasting environment. LAB test includes PSNR, distortion measure in image, and the watermark detection rate in the various attack environment such as AD/DA(analog to digital and digital to analog) conversion, noise addition, and MPEG compression. The result of LAB test is good for the TV advertisement monitoring. KOBACO and SBS are participated in the field test. The watermark detection rate is 100% in both the real-time processing and the saved the processing. The average deviation of the watermark detection time is 0.2 second, which is good because the permissible average error is 0.5 second.