Digital Image Watermarking and Encryption Using DWT and RSA

Abstract

In DWT based watermarking technique the cover image is decomposed to its frequency bands, the coefficients in these bands are modified to hide secret messages. The main characteristics of DWT Watermarking are the imperceptibility, capacity and low complexity. However, this technique has some limitations if it is used alone; it will not be efficient in terms of data security. In this paper the aim is to incorporate the DWT technique with the RSA public-key algorithm, to accomplish a high capacity and secure communication system. The difficulty of factoring in the RSA algorithm has made it one of the most powerful cryptosystems. The proposed technique aims to transfer high capacity secure data by embedding it inside the cover image without affecting or degrading the imperceptibility of the cover image. The security, capacity and imperceptibility are the main criteria according to which the performance of the system is judged. Many scenarios with different cover images and secret messages, different sizes and different image types, these scenarios are used to evaluate the performance of the proposed system by computing the PSNR and the corresponding payload sizes. For the system to not show any suspension of secret data that is being transferred, the value of the PSNR should be around 40dB, so a trade off must be made between security, capacity and imperceptibility to find to what extent this system can reach
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