Browsing by Author "Lee, Che-Wei"

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A covert communication method via spreadsheets by secret sharing with a self-authentication capability
(2013-02-01)
Lee, Che-Wei
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Tsai, Wen-Hsiang
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資訊工程學系
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Department of Computer Science
A new covert communication method with a self-authentication capability for secret data hiding in spreadsheets using the information sharing technique is proposed. At the sender site, a secret message is transformed into shares by Shamir's (k, n)-threshold secret sharing scheme with n = k + 1, and the generated k + 1 shares are embedded into the number items in a spreadsheet as if they are part of the spreadsheet content. And at the receiver site, every k shares among the k + 1 ones then are extracted from the stego-spreadsheet to recover k + 1 copies of the secret, and the consistency of the k + 1 copies in value is checked to determine whether the embedded shares are intact or not, achieving a new type of blind self-authentication of the embedded secret. By dividing the secret message into segments and applying to each segment the secret sharing scheme, the integrity and fidelity of the hidden secret message can be verified, achieving a covert communication process with the double functions of information hiding and self-authentication. Experimental results and discussions on data embedding capacity, authentication precision, and steganalysis issues are also included to show the feasibility of the proposed method. (c) 2012 Elsevier Inc. All rights reserved.
A data hiding method based on information sharing via PNG images for applications of color image authentication and metadata embedding
(2013-07-01)
Lee, Che-Wei
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Tsai, Wen-Hsiang
;
資訊工程學系
;
Department of Computer Science
A new data hiding method via PNG images based on Shamir's (k, n)-threshold secret sharing scheme is proposed. The coefficients of the polynomial used by the Shamir's method are taken as carriers to carry given data. The data to be hidden then are transformed into partial shares and embedded into the alpha-channel plane of a cover PNG image. Undesired white noise created in the resulting stego-image is removed by skillfully mapping the computed share values into suitable ranges in the embedding process. An important application of the proposed method to color image authentication is also proposed, with detailed authentication algorithms for PNG images presented. Compared with existing methods, the proposed image authentication method possesses the merits of losslessness during image authentication, high sensitivity to image alterations, good tampering localization capability, and very low false acceptance and rejection ratios. Experimental results proving the effectiveness of the proposed methods are also included. (C) 2013 Elsevier B.V. All rights reserved.
A Lossless Large-Volume Data Hiding Method Based on Histogram Shifting Using an Optimal Hierarchical Block Division Scheme
(2011-07-01)
Lee, Che-Wei
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Tsai, Wen-Hsiang
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資訊工程學系
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Department of Computer Science
A lossless large-volume data hiding method based on histogram shifting is proposed. The method is based on a scheme of hierarchically dividing a cover image into smaller blocks for data embedding using the histogram shifting technique, which yields a large data hiding capacity and results in a high stego-image quality. A technique for recursive looking-ahead estimation of the maximum data hiding volume at the lowest level of the block-division tree structure is proposed to yield an optimal data hiding result. The technique is shown to break a bottleneck of data-hiding-rate increasing at the image block size of 8 x 8, which is found to exist in other histogram-shifting methods. Four ways of block divisions are used, and one of them is selected optimally in each tree level of block divisions. A series of experiments have been conducted, and superiority of the proposed method to other related methods is shown by comparing the respective experimental results. A good property of the proposed method observed in the experiments is also pointed out, that is, the data hiding rate yielded by the proposed method increases without degrading the stego-image quality, which is an unusual phenomenon in data hiding researches.
A New Steganographic Method Based on Information Sharing via PNG Images
(2010-01-01)
Lee, Che-Wei
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Tsai, Wen-Hsiang
;
資訊工程學系
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多媒體工程研究所
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Department of Computer Science
A new steganographic method via PNG images based on the information sharing technique is proposed. The coefficients of the polynomial functions of the Shamir's (k, n)-threshold secret sharing method are utilized as carriers of a given secret data string to be hidden to generate shares. The shares then are embedded into the alpha-channel plane of a cover PNG image. The resulting stego-image with perceptible white noise is further removed by mapping computed share values into suitable ranges. Appropriate measures for enhancing the security of the proposed method are also described. Experimental results show the effect of the proposed method.
A Secret-Sharing-Based Method for Authentication of Grayscale Document Images via the Use of the PNG Image With a Data Repair Capability
(2012-01-01)
Lee, Che-Wei
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Tsai, Wen-Hsiang
;
資訊工程學系
;
Department of Computer Science
A new blind authentication method based on the secret sharing technique with a data repair capability for grayscale document images via the use of the Portable Network Graphics (PNG) image is proposed. An authentication signal is generated for each block of a grayscale document image, which, together with the binarized block content, is transformed into several shares using the Shamir secret sharing scheme. The involved parameters are carefully chosen so that as many shares as possible are generated and embedded into an alpha channel plane. The alpha channel plane is then combined with the original grayscale image to form a PNG image. During the embedding process, the computed share values are mapped into a range of alpha channel values near their maximum value of 255 to yield a transparent stego-image with a disguise effect. In the process of image authentication, an image block is marked as tampered if the authentication signal computed from the current block content does not match that extracted from the shares embedded in the alpha channel plane. Data repairing is then applied to each tampered block by a reverse Shamir scheme after collecting two shares from unmarked blocks. Measures for protecting the security of the data hidden in the alpha channel are also proposed. Good experimental results prove the effectiveness of the proposed method for real applications.
Optimal pixel-level self-repairing authentication method for grayscale images under a minimax criterion of distortion reduction
(2012-05-01)
Lee, Che-Wei
;
Tsai, Wen-Hsiang
;
資訊工程學系
;
Department of Computer Science
A new blind pixel-level self-repairing grayscale image authentication method, which is optimal under a minimax criterion of image-distortion reduction, is proposed. By dividing the grayscale range into bins, a three-bit bin code which provides the double functions of tampering localization and data repairing is generated as the authentication signal for each pixel in the cover image. The optimality in choosing three bits of a pixel as the authentication signal under a minimax criterion of minimizing the total maximum distortion resulting from authentication signal embedding and tampered pixel repairing is proved. Experimental results show the effectiveness of the proposed method. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.5.057006]