• Proceedings of the Korea Multimedia Society Conference
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• 1998.04a
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• pp.210-215
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• 1998

암호 통신의 한 방법으로 표면상의 의미 있는 형태를 유지하지만 실은 그 속에 중요한 기밀 정보를 숨겨놓은 심층암호(steganography)가 주목되고 있으며, 특히 디지털 화상을 이용하는 화상 심층암호는 저작권 보호 수단으로 활용되고 있다. 본 논문은 농담화상을 오차 확산법을 이용하여 흑·백의 2치로 의사적으로 표시하면서 기밀 정보를 합성하는 새로운 방식을 제안한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.530-533
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• 2000

암호 통신의 한 방법인 화상 심층암호(image steganography)는 화상 내에 기밀정보를 몰래 숨겨서 전송하는 것으로 표면상은 의미 있는 형태를 유지하지만, 실제로는 그 속에 기밀 정보를 몰래 은닉하는 형태로서 제3자는 기밀 정보의 존재 여부를 확인할 수 없기 때문에 공격의 위협을 감소시킬 수 있다. 특히 디지털 화상을 이용하는 화상 심층암호는 저작권 보호 수단으로 활용되고 있다. 본 논문은 256레벨의 그레이 화상에 다치 오차확산법을 이용하여 디더링을 수행하는 단계에서 기밀 정보를 은닉하는 새로운 방법을 제안한다

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.1-15
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• 2003

${Cachin}^{[1]}$ defined the security of steganography theoretically at first, then ${Katzenbeisser}^{[2]}$ and ${Hopper}^{[3]}$ also discussed it on the different aspects. Unfortunately, because many steganographic systems couldnt overcome the statistical gap between a stego-cover and a pure cover, the secure steganography hasn' been evaluated yet. By the effectivel steganalysis algorithm, statistical test which was suggested by Westfel $d^{［4］}$, the attacker Wendy could select the stego-covers out of suspicious covers. Our newly developed algorithm which minimizes the changes of a pure cover by using the block cipher withstands a statistical test and has a similar embedding capacity in comparison with a simple LSB substitution steganography.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.83-92
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• 2001

In this study, we combine information hiding technique with digital contents protection scheme. For providing secure distribution on digital contents, a new paradigm can be proposed after considering both watermarking and fingerprinting techniques. In detail, publicly verifiable digital signature schemes are applied into digital contents. On signing digital copyrights, we can publicly verify its correctness if needed.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.379-388
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• 2005

Image steganography Is a secret communication scheme to transmit a secret message, which is embedded into an image. The original image and the embedded image are called the cover image and the stego image, respectively. In other words, a sender embeds a secret message into a cover image and transmits a stego image to a receiver, while the receiver takes the stego image, extracts the message from it, and reads the message. General requirements for steganography are great capacity of secret messages, imperceptibility of stego images, and confidentiality between a sender and a receiver. In this paper, we propose a method for being satisfied with three requirements. In order to hide a secret message into a cover image safely, we use a difference value of two consecutive pixels and a secret quantization range. The former is used for the imperceptibility and the latter for the confidentiality. Furthermore, the number of insertion bits is changed according to the difference value for the imperceptibility. Through experiments, we have shown that our method is more good quality of stego images than many other related methods and increases the amount o( message insertion by performing dual insertion processing for some pixels.

• Journal of Korea Multimedia Society
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• v.7 no.7
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• pp.913-921
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• 2004

Steganography is a kind of data hiding which can hide secret information to digital media. It is performed so that another person does not recognize any information and make secret communication between each other. Specially, it is not easy to hide secret information without being visually recognized in scanned text image or cartoon image etc. In this paper, we propose an improved method that can embed a large quantity of secret information in a binary image without noticeable artifacts. Binary cartoon image is divided into block of 3-by-3 sizes. Secret information is embedded by using run-length of 8-neighborhood pixels except for the center pixel of the block. To improve the embedding capacity, we embed it into center pixel under to some condition.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.2
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• pp.113-119
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• 2006

Image steganography is a secret communication method used to transmit secret messages that have been embedded into an image. To accommodate a secret message in a digital image, the original cover image is modified by the embedding algorithm. As a result, a stego image is obtained. The sender hides the secret message in a cover image that has no meaning, and then transmits the stego image to the receiver. In this paper, we propose a steganographic method based on spatial domain to embed a secret message using a difference value of two consecutive pixels and a secret quantization range. Especially, we use the modular operation for increasing of insertion information. Through experiments, we have shown that the proposed method has much mon payload capacity, average 60 percent, than some existing methods by using modular operation.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.215-225
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• 2006

Binary images, such as cartoon character images, text images and signature images, which consist of two values with black and white have more difficulties inserting imperceptible secret data than color images. Steganography using binary cover images is not easy to satisfy requirements for both the imperceptibility of stego images and a high embedding rate of secret data at the same time. In this paper, we propose a scheme that can get both the high quality of stego images and a high embedding rate by supplementing the advantages of previous research. In addition, the insertion of the proposed method changes only existing pixels of the imperceptible position and can embed the secret data of [$log_2(mn+1)-2$] bits in a block with size of $m{\times}n$.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.39-47
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• 2004

In general, the steganographic algorithm for embedding message in JPEG images, such as Jsteg$^{(1)}$ , JP Hide ＆ Seek$^{(2)}$ , F5$^{(3)}$ , outGuess$^{(4)}$ replaces the LSB of DCT coefficients by the message bits. Both Jsteg and n Hide ＆ seek are detected by $\chi$$^2$- test, steganalytic technique$^{(4)}$ , the rate of detection is very low, though. In this Paper, we Propose a new steganalysis method that determine not only the existence of hidden messages in JPEG images exactly, but also the steganographic algorithm used. This method is advanced from the technique Blockiness$^{(5)}$ . It has many advantages that include a computational efficiency, correctness and that can detect without bowing steganographic algorithm. Experiment results show the superiority of our approach over Blockiness$^{(5)}$ .

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.11-22
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• 1997

The fractal image compression partitions an original image into blocks of equal size and searches a do-main block having self-similarity. This method of compression achieves high compression ratio because it is unnecessary to transmit the additional codebook to receiver and it provides good quality of reconstructed images. In spite of these advantages, this method has a drawback in which encoding time increase due to a complicated linear transformation for determining a similar-domain block. In this paper, a fast fractal image compression method is proposed by decreasing the number of transformation usings AC(alternating current) coefficients of block. The proposed method also has a good quality as compared with the well-known fractal codings. Furthermore, method also has a good quality as apply the video steganography that can conceal an important secret data.