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The demand for copyright protection of text documents is extremely vital especially when the text is transmitted over the Internet. One of the best practical resolutions to maintain the security of document media is digital watermarking. Several approaches have been proposed to guarantee the safety and protection of the documents against dishonest copying and distribution. This paper suggests an innovative zero-watermarking scheme for the purpose of authentication and tamper detection in simple text documents. The algorithm generates a watermark based on the effective characters of the text contents which can be extracted later using extraction algorithm to identify the status of tampering in the text document. Experimental results demonstrate the effectiveness of the algorithm against random tampering attacks. Watermark pattern matching and watermark distortion rate are used as evaluation parameters on multiple text samples of varying length.

Data hiding is a method of concealing secret data into a cover media and preventing a spectator from being aware of the existence of the hidden message. According to the problems of steganography, the main effort is to provide a better imperceptibility of stego-image that can be done by decreasing distortion of image. One of the popular techniques in data hiding is steganography in which the simple method for image hiding is the Least Significant Bit (LSB) substitution method. Wu et al. proposed two image hiding techniques to improve the quality of the stego-image [1]. The first one is to find the best block matching matrix and the other one is to find the optimal substitution matrices. The proposed method utilizes particle Swarm optimization (PSO) for finding the best pixel locations, and then the secret image is transformed to a new secret image. Optimal Pixel Adjustment (OPA) method is applied to further increase the quality of image. Results are then compared with those obtained by Simple LSB, Wang's et al. method, Wu's et al. method. The experimental results confirmed that PSNR of the proposed method is higher than mentioned methods which mean the imperceptibility of the image improves. Also the results illustrate that the proposed approach is robust against chi-square attack.

Text is an important medium used for sharing information worldwide. For a text document, digital watermarking is an efficient way for copyright protection, authentication, tamper proofing, to name but a few. In this paper, a zero-based watermarking approach is proposed for document authentication and tamper detection. To enhance the fragility of watermark, the proposed text watermarking approach can be comfortably utilizedbased on the Effective Characters List (ECL) for watermark generation. The ECL method is generated for English text zero-watermarking by maintaining the contents of the original document and constructing the watermark by formulating the smooth transition between the selected characters in the documents. The evaluation of the proposed watermarking approach is based on three famous watermarking attacks including deletion, insertion, and reordering with an accuracy of 80.76%, 80.36%, and 88.1%, respectively. For a fair evaluation, a comparison is put forth with a recent zero-based watermarking method-clearly showing that the proposed method outperforms existing with greater accuracy.

the main aim of this paper is to introduce a novel approach to preserve digital images' copyrights. Hence as ISB scheme was selected in relation to the approach in an attempt conquer the issues of robustness and imperceptibility in watermarked imagery. According to the literature review, embedding the aimed secret bits (Watermark) is a problematic issue inside a host image (normal 8-bit, grey-scale) in a sense to make it undetectable by the HVS (Human Visual System) in addition to the matter that it is predicted to receive any attacks. The suggested method here represents an improved scheme for the embedding of ISB which maintains the robustness and cultivates the rate of security by employing repeated bits in various bit planes over an irregular order and it develops the LSB technique specifically in circumstances where robustness and imperceptibility are main points of assessment.Digital image watermarking; Intermediate Significant Bit; robustness in watermarking;security;