Paillier Cryptosystem Based Robust and Reversible Image Watermarking

Watermarking is the method in which an image or a text is secretly embedded in an image taken as the original image. It is helpful in recognizing the original possessor of a particular content. It generally works on different objects like pictures, audio, video etc. Reversible and Robust Watermarking is a technique in which the original image as well as the watermarked image can be retrieved successfully even if the original or the image formed after the embedding phase is attacked by noise or other factors. This work is presenting an algorithm or a technique based on Robust and Reversible Watermarking. The algorithm presented in this work is divided into three phases: namely, watermark generation phase; the phase in which the generated watermark is inserted into the original image; and the phase of extraction of watermark and the original image separately or lossless. The watermark is obtained and embedded to the original image by using weber’s differential excitation descriptor, reference from law of weber, and interpolation linearly. Paillier Cryptosystem is used to encrypt the embedded image. To make the embedded image more secure, Discrete Wave Transform is applied. The original image is not necessary for the extraction process. Linear interpolation in inverse method is used to retrieve the value of the watermark of each block consisting of pixels. To determine the accuracy and robustness of the original image and the watermark that is extracted from the embedded image, different operations, or factors like PSNR, BER and Surviving bit rate are calculated. Random tampered zones could also be found using this algorithm.