Cross-channel color image encryption through 2D hyperchaotic hybrid map of optimization test functions

The security of chaos-based Image Encryption (IE) algorithms inherently depends on the permutation and diffusion strategy of the algorithm and the dynamic performance of chaotic maps. However, the existing studies suffer from low disordering capability, poor dynamic performance, and lack of sensitivity of the chaotic maps. In order to address these limitations, a Cross-Channel Color IE (CCC-IE) algorithm is presented, which has high shuffling ability with diagonal permutation and bi-directional sequential diffusion through a novel 2D hyperchaotic hybrid map of optimization test functions. The proposed 2D hyperchaotic map, namely 2D-RG map, is designed by hybridizing the Rastrigin and Griewank functions. Their chaotic nature, such as high complexity and fluctuation, makes them suitable for design of chaotic map. The 2D-RG map-based CCC-IE algorithm diagonally scrambles the pixels of the image across RGB channels and sequentially manipulates the pixel values in bi-direction for improving resistance of the algorithm to the cyberthreats. The dynamic performance of the 2D-RG map and the reliability of the CCC-IE algorithm are separately investigated and validated through a detailed comparison with the state of the art. The results manifest that the CCC-IE not only visually but also numerically is the more reliable algorithm thanks to the superior chaotic characteristics of the 2D-RG map.