Coupling chaotic system based on unit transform and its applications in image encryption

Abstract

Chaotic maps are very important for establishing chaos-based image encryption systems. This paper introduces a coupling chaotic system based on a certain unit transform, which can combine any two 1D chaotic maps to generate a new one with better performance in cryptography applications. The chaotic behavior analysis has verified this coupling system’s effectiveness and progress. In particular, we give a specific strategy about selecting an appropriate unit transform function to enhance the chaotic behaviors of generated maps. Besides, a new chaos-based pseudo-random number generator, shorted as CBPRNG, is designed to improve the randomness of chaotic sequences. Moreover, based on CBPRNG, a novel digital image encryption algorithm is introduced, where we design a two-way multi-round transformation network to encrypt the higher bits and lower bits of input images separately. Simulation results and security analysis indicate that the proposed image encryption scheme is competitive with some existing methods.