Chaotic image encryption using modular addition and combinatorial techniques

The image encryption is widely used to secure transmission of data in an open internet and internet works. For image based cryptosystems chaotic maps can be used as a key because of its nonlinear component. Due to sensitivity to initial conditions, chaotic maps have best alternative for designing dynamic permutation of the image based cryptosystem. A chaotic map is used to generate permutation matrix. An external secret key is used to derive the initial conditions for chaotic map. A pixel shuffling is used to expand diffusion property in the image and dissipate the high correlation among image pixels. The proposed algorithm is basically consisting of a pixel shuffling and modular addition plus permutation, which is a combination of block permutation, pixel permutation and value transformation. In general, diffusion and permutation is performed in a concurrent manner. These two methods are opened and operated alternatively in every round of encryption process at least four such chaotic sub keys are employed in every round of primitive encryption process. Decryption has the same structure, which operates in reverse order. Results of the various types of analysis are encouraging and imply that the proposed approach is able to adeptly trade off between the speed and protection. Hence, it is suitable for the secure transmission of image, video and multi-media in real-time. The proposed algorithm is tested for different types of statistical analysis by examining their autocorrelation, Cross Correlation (CC) performance, measuring the histogram of the cipher image and the bit error probability for the received data in a communication system.