Browsing by Author "Lee, Suiang-Shyan"

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All-in-one visual and computer decoding of multiple secrets: translated-flip VC with polynomial-style sharing
(2017-06-01)
Wu, Chia-Hua
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Lee, Suiang-Shyan
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Lin, Ja-Chen
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資訊工程學系
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Department of Computer Science
This all-in-one hiding method creates two transparencies that have several decoding options: visual decoding with or without translation flipping and computer decoding. In visual decoding, two less-important (or fake) binary secret images S1 and S2 can be revealed. S1 is viewed by the direct stacking of two transparencies. S2 is viewed by flipping one transparency and translating the other to a specified coordinate before stacking. Finally, important/true secret files can be decrypted by a computer using the information extracted from transparencies. The encoding process to hide this information includes the translated-flip visual cryptography, block types, the ways to use polynomial-style sharing, and linear congruential generator. If a thief obtained both transparencies, which are stored in distinct places, he still needs to find the values of keys used in computer decoding to break through after viewing S1 and/or S2 by stacking. However, the thief might just try every other kind of stacking and finally quit finding more secrets; for computer decoding is totally different from stacking decoding. Unlike traditional image hiding that uses images as host media, our method hides fine gray-level images in binary transparencies. Thus, our host media are transparencies. Comparisons and analysis are provided. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
An accelerated K-means clustering algorithm using selection and erasure rules
(2012-10-01)
Lee, Suiang-Shyan
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Lin, Ja-Chen
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資訊工程學系
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Department of Computer Science
The K-means method is a well-known clustering algorithm with an extensive range of applications, such as biological classification, disease analysis, data mining, and image compression. However, the plain K-means method is not fast when the number of clusters or the number of data points becomes large. A modified K-means algorithm was presented by Fahim et al. (2006). The modified algorithm produced clusters whose mean square error was very similar to that of the plain K-means, but the execution time was shorter. In this study, we try to further increase its speed. There are two rules in our method: a selection rule, used to acquire a good candidate as the initial center to be checked, and an erasure rule, used to delete one or many unqualified centers each time a specified condition is satisfied. Our clustering results are identical to those of Fahim et al. (2006). However, our method further cuts computation time when the number of clusters increases. The mathematical reasoning used in our design is included.
Progressive sharing of multiple images with sensitivity-controlled decoding
(2015-02-14)
Chang, Sheng-Yu
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Lee, Suiang-Shyan
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Yeh, Tzu-Min
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Chen, Lee Shu-Teng
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Lin, Ja-Chen
Secure sharing of digital images is becoming an important issue. Consequently, many schemes for ensuring image sharing security have been proposed. However, existing approaches focus on the sharing of a single image, rather than multiple images. We propose three kinds of sharing methods that progressively reveal n given secret images according to the sensitivity level of each image. Method 1 divides each secret image into n parts and then combines and hides the parts of the images to get n steganographic (stego) JPEG codes of equal importance. Method 2 is similar; however, it allocates different stego JPEG codes of different 'weights' to indicate their strength. Method 3 first applies traditional threshold-sharing to the n secret images, then progressively shares k keys, and finally combines the two sharing results to get n stego JPEG codes. In the recovery phase, various parameters are compared to a pre-specified low/middle/high (L/M/H) threshold and, according to the respective method, determine whether or not secret images are reconstructed and the quality of the images reconstructed. The results of experiments conducted verify the efficacy of our methods.
Protection of 3D models using cross recovery
(2017-01)
Lee, Suiang-Shyan
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Huang, Yi-Jheng
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Lin, Ja-Chen
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資訊工程學系
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Department of Computer Science
This paper proposes a cross recovery scheme to protect a group of 3D models. The lost or damaged models can be reconstructed using the mutual support of the survived authenticated models. In the encoding phase, we convert a group of n given models (called host models) into n stego* models. The n stego* models would still preserve the appearance of the n host models. In the decoding phase, we divide the received models into two groups: authenticated vs. non-authenticated. Then, we rebuild the recovered models of the non-authenticated group by the mutual support of any t authenticated models (t < n is a given parameter). The experimental results show that the visual quality of our stego* models is very similar to that of the host models, and the size of the stego* models is also very similar to that of the host models. Moreover, after hacker\'s attack or disk crash, if the number of attacked or crashed stego* models is not larger than n - t, then the damaged or lost models can be recovered, and the recovered models still have acceptable quality. We also provide an equation which can estimate the suitable size of the recovered model in advance.
WEB-VC: VISUAL CRYPTOGRAPHY FOR WEB IMAGE
(2019-01-01)
Lee, Suiang-Shyan
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Huang, Yi-Jheng
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Lin, Ja-Chen
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資訊工程學系
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Department of Computer Science
y The conventional encryption techniques of visual cryptography are extended to web page. The key point is that Cascading Style Sheet blend modes can simulate stacking operators. The multiply blend mode can be regarded as Boolean OR operator, and the difference blend mode can be regarded as exclusive-OR (XOR) operator. Thus, the secrets can be revealed in a web browser by overlapping shares together without any additional computation. We named this scheme Web-VC. The decoding procedure of Web-VC is just like usual visual cryptography, while digital shares can be used in this case. Web-VC has strong ability of resisting compression and transcoding without losing the secret. Another contribution of this work is the method of XOR-based flip visual cryptography.