Experimental evaluation of the text documents marking algorithm based on interword distances shifting

The article presents the experimental parameter evaluation results of the electronic documents marking algorithm, based on interword distances shifting. The developed marking algorithm is designed to increase the security of electronic documents containing textual information from leakage through channels caused by printing, scanning or photographing, followed by sending the generated image. The algorithm analyzed parameters are such characteristics as embedding capacity, invisibility, undetectability, extractability and robustness. In the course of embedding capacity estimation of the developed algorithm, analytical expressions are given that make it possible to calculate the maximum achievable embedding capacity value. The obtained quantitative estimates and the experiments carried out made it possible to substantiate the admissible values choice of the embedded marker. To determine the embedded information invisibility in the source document, an invisibility and undetectability assessment of the embedded marker was carried out. During the expert evaluation, the developed algorithm invisibility to visual analysis was substantiated, as well as the absence of significant statistical deviations in the distribution of the analyzed parameters in the process of assessing the resistance of the developed marking algorithm to the potentially best steganographic analysis method. The quantitative extractability of the developed marking algorithm was carried out by assessing the extraction accuracy. The analysis performed showed accuracy high values of marker extraction from scanned images, which makes it possible to reliably extract embedded data, as well as determine directions for improving the extraction accuracy from photographed images. In the assessing process the stability of the developed marking algorithm to the transformations implementation and distortions introduction, the main robustness parameters of the developed marking algorithm to the printing, scanning and photographing processes are determined. Conclusions are formulated on the using possibility the developed marking algorithm and directions for further researches are identified.