New Chaos based Secure Image Encryption and Analysis

Abstract

newline Images have now become integral parts of digital data stored and processed in computer databases and transferred over the Internet. Confidentiality of such digital images newlineis a major concern. This thesis is focused on development of three image encryption newlinealgorithms based on permutation (confusion) and pixel value modification (diffusion) newlineprocesses with the help of pseudo random number sequences (PRNS) generated by newlinechaotic mathematical functions. High computational overhead resulting in considerable newlinedelay in encryption/decryption process is the main limitations of most of the encryption newlineschemes reported in literature during the last two decades. The proposed algorithms newlinenot only fulfill the requirement of robustness against attacks, but also execute very fast newlineeven on most resource constrained systems. This thesis describes a few Pseudo Random Number Generators (PRNG) and their use in designing new chaos based cryptosystems. As the strength and complexity of the crypto-systems are highly dependent on newlinethe quality of PRNG used, multiple chaotic maps are combined and used to design new newlineimproved PRNG with higher randomness as well as fast execution speed. Operations newlinelike XOR and DNA computations, which have very low computational overhead, are newlineused for pixel substitution (diffusion) process. Efforts were made to reduce the overall newlinecomputational complexity of the algorithms while maintaining their security strength. newlineThe experimental outcomes of our proposed algorithms are encouraging and competitive when compared with standard values and results of other algorithms published in newlinethe literature. The suggested algorithms run with minimal computational cost, making newlinethem robust and trustful encryption schemes for resource restricted systems. These algorithms can be extended for encrypting audio, video and text data as well. Further, we newlineanalyzed the present security trends in Indian e-governance system and speculated the newlinefuture trends