Attack resistant chaos-based cryptosystem by modified baker map and logistic map

In this paper, a new substitution-diffusion type chaos-based cryptosystem is proposed, which can encrypt greyscale images having arbitrary resolution. In substitution, image pixels are permuted using a modified form of the discretised 2-D Baker map, followed by a two-step diffusion approach, which employs a chaotic logistic map. The proposed cryptosystem is resistant to brute force attacks (measured by key-space and key-sensitivity analysis), statistical attacks (tested by histogram and chi-square test) and differential attacks (measured against NPCR, UACI, and hamming distance); the proposed method has also been tested for encryption quality, correlation analysis, entropy analysis, and performance analysis by measuring encryption speed as well as time complexity. Therefore, it is sufficiently secured to be used in real-world applications. To prove the unparalleled outcome of the proposed system, four sets of comparisons have been presented with respect to NPCR and UACI, Encryption throughput, and, lastly, with similar and non-similar existing cryptosystems.