Chaotic encryption scheme based on a fast permutation and diffusion structure

The image encryption architecture presented in this paper employs a novel permutation and diffusion strategy based on the sorting of chaotic solutions of the Linear Diophantine Equation (LDE) which aims to reduce the computational time observed in Chong's permutation structure. In this scheme, firstly, the sequence generated by the combination of Piecewise Linear Chaotic Map (PWLCM) with solutions of LDE is used as a permutation key to shuffle the sub-image. Secondly, the shuffled sub-image is masked by using diffusion scheme based on Chebyshev map. Finally, in order to improve the influence of the encrypted image to the statistical attack, the recombined image is again shuffle by using the same permutation strategy applied in the first step. The design of the proposed algorithm is simple and efficient, and based on three phases which provide the necessary properties for a secure image encryption algorithm. According to NIST randomness tests the image sequence encrypted by the proposed algorithm passes all the statistical tests with the high P-values. Extensive cryptanalysis has also been performed and results of our analysis indicate that the scheme is satisfactory in term of the superior security and high speed as compared to the existing algorithms.