A novel multiple grayscale image encryption method based on 3D bit-scrambling and diffusion

Since a large number of digital images are shared widely in our daily life, the demand and need for multiple-image encryption algorithms are increasing to ensure the security of the shared images. To present a new perspective to this request, a secure multiple-image encryption method based on 3D bit-scrambling and diffusion operations is proposed for grayscale images in this paper. A three-dimensional bit array is created by extending the eight bit planes of each grayscale image to a third dimension. This 3D bit array is pseudo-randomly scrambled by changing the order of the rows, columns, and layers. The scrambled bit planes are then used to reconstruct the shuffled images. A controlled diffusion operation is also applied to the shuffled and merged images. Both scrambling and diffusion parameters are obtained separately by iterating the chaotic Henon map twice. The initial values of the Henon map are plain images dependent. Several performance analyses including key space and sensitivity, histogram, correlation, entropy, differential, data loss, noise, and running time are carried out to test the proposed method’s resistance against various cryptanalytic attacks. Simulation results show that the proposed method can encrypt multiple images effectively and securely.