• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.5
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• pp.2258-2274
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• 2020

In this paper we first propose a new cryptosystem based on our data hiding scheme (2,9,8) introduced in 2019 with high security, where encrypting and hiding are done at once, the ciphertext does not depend on the input image size as existing hybrid techniques of cryptography and steganography. We then exploit our automata approach presented in 2019 to design two algorithms for exact and approximate pattern matching on secret data encrypted by our cryptosystem. Theoretical analyses remark that these algorithms both have O(n) time complexity in the worst case, where for the approximate algorithm, we assume that it uses ⌈(1-ε)m)⌉ processors, where ε, m and n are the error of our string similarity measure and lengths of the pattern and secret data, respectively. In searchable encryption, our cryptosystem is used by users and our pattern matching algorithms are performed by cloud providers.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.5
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• pp.37-42
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• 2012

Audio steganography is quite similar to the procedure of modifying the least significant bit(LSB) of image media files. The most widely used technique today is hiding of secret messages into a digitized audio signal. In this paper, I propose a new method for hiding messages from attackers, high data inserting rate is achieved. In other words, based on the LSB hiding method and digitized to change the bit position of a secret message, an encrypted stego medium sent to the destination in safe way.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2004.06a
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• pp.95-98
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• 2004

본 논문에서는 결합변환상관기(joint transform correlator)와 위상 암호화된 영상들을 이용하여 영상의 인식 및 복호화가 가능한 광 암호화 시스템을 제안하였다. 그레이 값을 가지는 원 영상은 동일한 그레이 값을 가지는 이진 영상으로 나누어 표현할 있다. 이러한 이진 영상들을 각각의 다른 이진 무작위 영상과 위상 부호화한 XOR 연산을 이용해 암호화할 수 있으며. 암호화한 영상들을 결합한 후 위상 부호화 과정을 거쳐 최종 암호화 영상를 구한다. 키 영상은 암호화에 사용된 각각의 이진 무작위 영상들을 최종 암호와 영상를 얻을때의 과정처럼 결합하여 역시 하나의 영상으로 구할 수 있다. 최종 암호화 영상과 키 영상을 제안한 결합변환상관기의 입력으로 사용하여 구한 상관치는 높고 폭이 좁은 특성을 가지고 있으므로 분별성능이 좋은 인식 시스템을 구현할 수 있을 뿐만 아니라 복호화 영상도 구할 수 있다. 컴퓨터 모의 실험으로 제안한 방법을 확인해보았다.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.403-413
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• 2011

In this paper, we proposed a digital image watermarking technique using scrambled binary phase computer generated hologram in the discrete cosine transform(DCT) domain. For the embedding process of watermark. Using simulated annealing algorithm, we would generate a binary phase computer generated hologram(BPCGH) which can reconstruct hidden image perfectly instead of hidden image and encrypt it through the scramble operation. We multiply the encrypted watermark by the weight function and embed it into the DC coefficients in the DCT domain of host image and an inverse DCT is performed. For the extracting process of watermark, we compare the DC coefficients of watermarked image and original host image in the DCT domain and dividing it by the weight function and decrypt it using descramble operation. And we recover the hidden image by inverse Fourier transforming the decrypted watermark. Finally, we compute the correlation between the original hidden image and recovered hidden image to determine if a watermark exits in the host image. The proposed watermarking technique use the hologram information of hidden image which consist of binary values and scramble encryption technique so it is very secure and robust to the various external attacks such as compression, noises and cropping. We confirmed the advantages of the proposed watermarking technique through the computer simulations.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.3
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• pp.277-282
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• 2018

The goal of the secret message communication on the internet is to maintain invisibility and confidentiality. Digital steganography is a technique in which a secret message is inserted in a cover medium and transmitted to a destination so that a third party can not perceive the existence of the message itself. Steganography is an efficient method for ensuring confidentiality and integrity together with encryption techniques. In order to insert a secret (Hangul) message, I propose a image steganography method that the secret character is separated and converted into binary code with reference to the encryption table, the cover image is divided into two areas, and the secret message and the right l-LSB information of the second area are encrypted and crossed, concealing the k-LSB of the first region. The experimental results of the proposed method show that the PSNR value is 52.62 and the acceptable image quality level.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.400-407
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• 2003

In this paper an optical encryption system, which can decrypt the original image by using the autocorrelation terms of a JTC, is proposed. Unlike the classical JTC, the joint input plane of the proposed system is composed in a frequency domain not a spatial domain, thus it needs only one Fourier transformation. To use like this, the phase component appeared in the output plane of JTC should be considered. We presents the effect of phase and provides the solution. An original image is encrypted to a complex-valued random image. The original image is reconstructed using the autocorrelation terms which is the main drawback of JTC, therefore the proposed system is more suitable for JTC and real time processing. By computer simulation and optical experiment, the analysis for the phase effect and the performance of the proposed system are confirmed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.141-143
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• 2010

This paper presents a problem of the existing encryption method using MLCA or complemented MLCA and propose a method to resolve this problem. With the existing encryption methods, the result of encryption is affected by the original image because of spatial redundancy of adjacent pixels. In this proposed method, we transform spatial coordinates of all pixels into encrypted coordinates. We also encrypt color values of the original image by operating XOR with pseudo-random numbers. This can solve the problem of existing methods and improve the levels of encryption by randomly encrypting pixel coordinates and pixel values of original image. The effectiveness of the proposed method is proved by conducting histogram, key space analysis.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.58-65
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• 2007

This dissertation proposes digital video protection algorithm lot moving image based on MPEG. Shuffling-based encryption algorithms using a fixed random shuffling table are quite simple and effective but vulnerable to the chosen plaintext attack. To overcome this problem, it is necessary to change the key used for generation of the shuffling table. However, this may pose a significant burden on the security key management system. A better approach is to generate the shuffling table based on the local feature of an image. In order to withstand the chosen plaintext attack, at first, we propose a interleaving algorithm that is adaptive to the local feature of an image. Secondly, using the multiple shuffling method which is combined interleaving with existing random shuffling method, we encrypted the DPCM processed 8*8 blocks. Experimental results showed that the proposed algorithm needs only 10% time of SEED encryption algorithm and moreover there is no overhead bit. In video sequence encryption, multiple random shuffling algorithms are used to encrypt the DC and AC coefficients of intra frame, and motion vector encryption and macroblock shuffling are used to encrypt the intra-coded macroblock in predicted frame.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2933-2942
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• 2015

This paper proposes a new method which traces significant element of 2-dimensional natural images and encrypts them by using Fresnelet transform (FRNLT). After analyzing property of the subbands obtained by the FRNLT, we estimated the information for ciphering 2D images. Considering FRNLT levels, energy of subbands, and visual effect, we estimated the optimized point for encryption. By selecting various levels and encrypting region, we can encrypt 2D image with various robustness. Encryption effectiveness was showed by analyzing numerical result, executing time for encryption, area of encrypted region, and visual observation. Therefore encryption for various application can be applied by using the suggested parameters without additional analysis. Identifying the experimental result, in the case of $L_{TH}=4$ and $L_{TH}=4$, an image was not recognized through encrypting only 0.42% among the entire data.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.431-442
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• 2018

2-dimensional barcode, QR code has been used for containing various information such as image, video, map, and business cards. Currently, a smartphone is used as a QR code scanner, displaying the code and converting it to a standard URL for a website. However, QR codes are not very common in encrypted application and so have a few applications. This paper proposes a new color-code, which integrates the conventional QR code and color design, and can be effectively used in some product certification system. The proposed method exploits the fact that genuine code is produced by CMYK color model, but the counterfeit is captured by RGB color model and during this process, color information of the code is changed. This paper introduces the color matrix model to measure the distortion between genuine code and counterfeit code. By investigating the statistical characteristics of color matrix, an effective detection of print image forgeries are designed. Various experiments with color codes show that the proposed system can be effectively used in product certification systems.