Enhanced image encryption and watermarking systems using hybrid techniques

Abstract

Securing data flowing over the network has become a crucial need of the hour. Nowadays not only casual massages are exchanged, but confidential information related to business transaction and data associated with national security also flows over the media and this need to be safeguarded and protected. Attacker may modify or destroy it partially or completely which may lead to failure of basic purpose of communication. In order to avoid such scenario, the information may be encrypted before uploading it over media, with proper authentication procedure to prevent unauthorized access. newlineThe thesis proposes hybrid optoelectronic encryption and watermarking models extending the work in new spheres of hybrid transform, multi-resolution wavelet transform and 2D non-separable linear canonical transform (2D NS-LCT). The decomposition techniques utilized here comprises of modified equal modulus decomposition and random decomposition. newlineIn the third chapter, three hybrid encryption schemes for encoding data are proposed. The modified equal modulus decomposition and random decomposition techniques have been explored in hybrid multiresolution wavelet and hybrid transform domain. Chaotic systems have been employed to further strengthen the proposed schemes; they not only extend the key space but also decorrelate the pixels of the resultant encrypted image. In the next chapter, three hybrid watermarking schemes for embedding invisible watermark image in a host image are proposed. While designing the schemes the modified equal modulus decomposition and random decomposition techniques have been explored in hybrid multiresolution wavelet and 2D NS-LCT transform. To further strengthen the watermarking scheme chaotic systems have been employed for decorrelating pixels of the resultant encrypted image. Later on, iris biometric fortification scheme employing 4D hyperchaotic framework and modified equal modulus decomposition in hybrid multi resolution wavelet domain is proposed. newlineTo validate and estimate the performance of the proposed mechanisms, key sensitivity, statistical, attack and comparison analysis have been carried out. Data set used for testing and evaluation of the proposed methods comprises of standard grayscale images of Lena, Peppers, Barbara, Gaza pyramid Egypt, iris and iris template images from Hong Kong Polytechnic University Cross-Spectral Iris Images Database along with newlinemy own pics. Results obtained clearly demonstrate that the proposed methods provide stronger encryption and higher robustness against iterative transform-based attacks compared to existing methods. newline newline newline