An efficient and secure SPN cryptosystem based on chaotic control parameters

In this paper, we propose a new fast and secure scheme for image encryption based on a robust uniform chaotic pseudo-random generator. This generator is used to provide the control parameters of substitution and permutation. Many image encryption algorithms use fixed control parameters in the permutation and substitution stages, during the whole encryption process, which can be easily attacked. The proposed cryptosystem presents a substitution process of the gray value based on a discretized skew tent map, and a bits permutation process based on the standard map. The substitution and permutation processes are done by controlling in a chaotic manner the parameters of the skew tent and standard maps. The proposed cryptosystem has a large key space. It is suitable for software and hardware implementations. Theoretical and simulation results of the proposed cryptosystem show that it is immune against linear, differential, chosen/known-plaintext, brute force, and statistical attacks.