• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.155-162
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• 2008

The security of digital image has become increasingly important with the development of the computing performance and internet. Therefore, the encryption algorithms exploiting chaos signal have recently attracted considerable attentions as a new method of image-encryption techniques. In this Paper, it is demonstrated that two different chaotic systems are synchronized by the methods of noise-induced synchronization. Based on this synchronization method, an image-encryption system is implemented and an image of Seok-Ga-Tap is encrypted as a verification of the performance of our system. The method suggested in this paper in which the noise is used as the key of decryption is superior to the existing methods in the aspect of the degree of encryption. In this paper, we Propose that the method is a new effective encryption algorithm as well as an easily applicable one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1477-1484
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• 2015

In this paper, a novel reversible data hiding by using Reed-Solomon (RS) code is proposed for efficient transmission in encryption image. To increase the recovery of data from encrypted image, RS codes are used to encode messages, and then the codewords can be embedded into encrypted image according to encryption key. After receiving encrypted image which embeds the codewords, the receiver firstly decryptes the encrypted image using the encryption key and get metric about codewords containing messages. According to recovery capability of RS codes, better estimation of message is done in data hiding system. Simulation results about two images and two RS codes show that the performances of the proposed schemes are better than ones of the reference scheme.

• Journal of KIISE
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• v.42 no.2
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• pp.162-168
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• 2015

Image data is mostly stored in compressed form because of its huge size. Therefore, a series of cumbersome procedures is required to apply a transformation to image data: decompression, extraction of spatial data, transformation and recompression. In this paper, we employ DCT(Discrete Cosine Transform) coefficients to change the spatial presentation of images. DCT is commonly used in still image compression standards such as JPEG and moving picture compression standards such as MPEG-2, MPEG-4, and H.264. In this paper, we derived mathematically the relationship between the geometry transformation in the spatial domain and coefficient changes in the DCT domain and verified it with images in the JPEG file format. Because of the efficiency of transformation in the frequency domain, our findings can be utilized for light-weight partial image encryption for privacy data protection or entertainment contents protection.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.266-267
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• 2004

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.325-327
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• 2004

무선 인터넷의 보급과 맞물려 모바일 컴퓨팅 환경이 구축됨에 따라 PDA와 같은 소형의 모바일 장비에 최적화된 디지털 컨텐츠의 제작 및 배포가 활발해지고 있으며 불법적인 디지털 컨텐츠의 이용 또한 이에 비례하고 있다. 그러나 유선환경에 기반 한 기존의 DRM 시스템은 상대적으로 속도와 표현능력이 떨어지는 모바일 환경에는 적합하지 않으며 현재 연구.개발된 모바일 환경에서의 DRM 시스템은 음악, 문서, 이미지에 국한되어 있어 동영상과 암호화와 같은 높은 연산 능력을 요구하는 부분의 개발과 연구는 초기 단계에 머물러 있다. 본 논문에서는 모바일 환경에 적합하도록 적은 연산 능력으로도 기존의 DRM 시스템에 준하는 보안 강도를 갖을 수 있도록 동영상의 부분 암호화 방식과 공유키 풀 기반의 인증 방법을 사용하는 DRM 시스템을 설계ㆍ제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.331-337
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• 2017

In this work, we propose an improved form of Zhang's reversible data hiding technique in encrypted image. In the original work, average value of neighboring pixels is used for fluctuation calculation which fails to give good performance. In proposed scheme, to reduce the bit error rate a new function is calculated by summing difference from four neighboring pixels for measuring fluctuation. Moreover, modified calculation of fluctuation function is also proposed where border pixels are considered. The simulation results show that the performance of proposed method outperforms Zhang's and Hong's work. From the results, more information can be sent by using proposed system

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.759-762
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• 2017

The proposed scheme is proposed secure transmission of fixed data and unstructured data among medical information transmitted in PACS. Unstructured data uses the AES encryption algorithm as sensitive data And transmitted using encrypted mosaic encryption techniques for the non-identification of medical images, which are regular data. In addition, we have experimented with increasing the key size for encryption. As a result, we did not notice any significant difference between 128 - bit size and 128 - key size even when encrypting the size of 196,256.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1767-1770
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• 2003

PDA 는 터치패드 방식의 문자 입력을 한다. 따라서 사용자에게 긴 입력을 요구할 때 불편한 환경을 제공한다. 따라서 이미지의 특정 지점을 마우스로 선택함으로 문자입력을 대신하여 인증을 함으로써 편리한 환경을 제공한다. 보안을 제공하기 위하여 초기 이미지에 따른 이미지의 배열 정보 및 입력된 값을 해시코드화 하여 인증 및 키교환이 안전하게 이루어진다. HASH와 SEED 암호화 알고리즘을 적용하여 효율적이고, 전송 메시지의 무결성을 보장하며 내부 참여자에 의한 정보 유출이 있더라도 안전한 전자지불 프로토콜 시스템을 설계 및 구현하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.811-819
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• 2012

In this paper, we design searchable image encryption system to provide the privacy and authentication on streaming media based on cloud computing. The searchable encryption system is the matrix of searchable image encryption system by extending the streaming search from text search, the search of the streaming service is available, and supports personal privacy and authentication using encryption/decryption and CBIR technique. In simple simulation of post-cut and image keyword creation, we can verify the possibilities of the searchable image encryption system based on streaming service.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.796-798
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• 2001

본 논문에서는 벡터 양자화(Vector Quantization)를 이용해서 소유자의 저작물에 대해 저작권을 보호할 수 있는 디지털 워터마킹(Watermarking) 기법을 제안한다. 소유자의 워터마크 정보로는 사용자 정보를 비밀키를 이용해서 암호화한 데이터를 사용하며, 워터마킹 처리는 원본 이미지를 웨이블렛 기반의 벡터 양자화(Vector Quantization)에 사용되는 코드북(Coodbook)을 이용한다. 코드북을 사용함으로서 양질의 정보를 유지하면서 워터마킹을 효과적으로 처리할 수 있다.