Jong-Uk Choi

Securing E-Government Services

Widespread Internet access is making it possible for governments around the world to move information and services online, providing substantial savings in cost, time, and labor. By letting citizens interact with the government from their own computer rather than in person, e-government also enhances quality of service and accessibility. However, economy and convenience must be traded off against security. Online systems are vulnerable to hackers, and the government has an obligation to prevent the unauthorized disclosure of personal information as well as prevent forgery and alteration of official documents

An audio copyright protection schemes based on SMM in cepstrum domain

In this paper, we present an audio scheme protective of copyright protection using information hiding. We propose visually recognizable binary image and text information as watermark (copyright) information embedded in audio signal. Cepstrum representation of audio can be shown to be very robust to a wide range of attacks. We apply SMM(statistical mean manipulation) theory in embedding image watermarking, and address attacks against lossy audio compression like MP3, white Gaussian noise and so on. A blind detection watermarking can be realized with the proposed scheme.

Technologies for Online Issuing Service of Documents

With the wide spread use of Internet, many government organizations are trying to implement e-government projects to provide on-line service and to improve productivity of public service. Because not all services are performed electronically, however, it is necessary to development technologies for enhancing the convenience of services for citizens by linking online digital documents and offline printed documents. This study investigated technologies and frameworks for issuing online documents such as certificates in e-Government, and examined cases of service to which the technologies and frameworks were applied.

Holographic Image Watermarking for Secure Content

We propose a new watermarking scheme that can be used to embed multiple bits and also resilient to geometrical transforms such as scaling, rotation, and cropping, based on off-axis holographic watermark that allows multiple watermark recovery without original content(cover image). The holographic watermark is that Fourier transformed digital hologram is embedded into cover image in the spatial domain. The proposed method has not only increased robustness with a stronger embedding but also imperceptibility of the watermark in the evaluation process. To compare with the conventional scheme, the spread spectrum, we embedded and recovered maximum 1,024 bits that consist of binary number over PSNR(peak signal-to-noise ratio) 39dB. And also, we computed robustness with BER(bit-error rate) corresponding the above attacks.

Image forensics technology for digital camera

Even though digital devices, especially digital cameras and camcoders, are getting popular, they are not counted in legal disputes as trustworthy devices. In this paper an image forensics technology is proposed to make digital image capturing devices have legal proof capabilities. For the images taken by digital devices to have legal proof capability, integrity should be guaranteed. Electronic signature was proposed as a means of guaranteeing the integrity of the digital files of images. However, electronic signatures require additional data of digital digest, and cannot survive digital manipulations such as lossy compression, or RST (rotation, scaling, and transformation). This paper suggests a novel algorithm of image forensics that guarantees integrity in nor-mal processing by hiding forensics information into images and identifies locations of forgery and alteration. Images produced by the proposed method maintains high image quality as PSNR over 50[dB] and guarantees integrity up to the quality factor of 85% against JPEG compression.

Improved Similarity Detection Algorithm of the Video Scene

We proposed similarity detection method of the video frame data that extracts the feature data of own video frame and creates the 1-D signal in this paper. We get the similar frame boundary and make the representative frames within the frame boundary to extract the similarity extraction between video. Representative frames make blurring frames and extract the feature data using DOG values. Finally, we convert the feature data into the 1-D signal and compare the contents similarity. The experimental results show that the proposed algorithm get over 0.9 similarity value against noise addition, rotation change, size change, frame delete, frame cutting.

Audio Blind Watermarking Robust Against HE-AAC

In this paper, we propose a replica based audio blind watermarking algorithm which is robust against High Efficiency Advanced Audio Coding (HE-AAC). The algorithm embeds watermarks by modulating normalized correlation of original signal and its delayed version. The modulation can be done by adding modulated replica signal at a specified delay to the host signal. The watermark embedding strength is determined by signal-to-noise ratio (SNR) before and after HE-AAC compression. And a feedback process is implemented to ensure the watermark embedding strength has achieved. Experimental results show the proposed watermarking algorithm highly robust to HE-AAC compression while maintaining good imperceptibility.

Reversible Watermarking Based On Advanced Histogram Shifting

In this paper, we propose a reversible watermarking method to recover an original image after the watermark has been extracted. Most watermarking algorithms cause degradation of image quality in original digital content in the process of embedding watermark. In the proposed algorithm, the original image can be obtained when the degradation is removed from the watermarked image after extracting watermark information. In the proposed method, we utilize histogram shifting concept and Location Map structure. We could solve the Filp-Flop problem by using Location Map structure and enlarge the information embedding capacity by embedding recursively. Experimental results demonstrate that the embedding information as large as 120k bits can be realized while the invisibility as high as 41dB can be maintained.

Broadcast synchronizing system using audio watermark

In this paper, we propose the audio watermarking algorithm based on the critical band of HAS(human auditory system) without audibly affecting the quality of the watermarked audio and implement the detecting algorithm on the BSS(broadcast synchronizing system) for testing the proposed algorithm. According to the audio quality test, the SNR(signal to noise ratio) of the watermarked audio objectively is 66dB above. In the robustness test, the proposed algorithm can detect the watermark more than 90% from various compression (MP3, AAC), A/D and D/A conversions, sampling rate conversions and especially asynchronizing attacks. The BSS automatically switches the programs between the key station and the local station in broadcasting system. The result of reliability test of implemented system by using the real broadcasting audio has no false positive error during 90 days. Because of detecting once processing per 0.5 second, we can judge that the false positive error does not nearly occur.

A robust digital watermarking in geometric attacks

We propose a new watermarking scheme that can be used to embed multiple bits and also resilient to JPEG compression and geometrical transforms such as scaling, rotation, and cropping, based on holographic watermark that allows multiple watermark recovery without original content (cover image). The holographic watermark is that Fourier transformed digital hologram, embedded into cover image in the spatial domain. The proposed method has not only increased robustness with a stronger embedding but also imperceptibility of the watermark in the evaluation process. To compare with the conventional scheme, the spread spectrum, we embedded and recovered maximum 1,024 bits that consist of binary number over PSNR (peak signal-to-noise ratio) 39dB. And also, we computed robustness with BER (bit-error rate) corresponding the above attacks.