Optical and digital double color-image encryption algorithm using 3D chaotic map and 2D-multiple parameter fractional discrete cosine transform

Abstract

This paper proposes a new encryption and decryption method for optical and digital double color-images using 2D-multiple parameter fractional discrete cosine transform (MPFrDCT) and 3D-logistic chaotic map (3D-LCM). The double color-images to be encrypted are converted to their indexed formats by extracting their color maps. A 3D-LCM is used for generate a keystream and this keystream is used in scrambling the indexed images. The second scrambled image is normalized and then multiplied by a random phase mask (RPM) generated by 3D-LCM. The first scrambled image and the second modified image are treated as amplitude and phase of a complex signal and this complex signal is encrypted using 2D-MPFrDCT. The Encrypted image is obtained after separating the amplitude and phase parts of this signal. To enhance security, a substitution method is applied in the intermediate image using another keystream generated by 3D-LCM. The decryption method is the same but in reverse order. We have also given a setup for the encryption and decryption of optical double images using this method. The keyspace for the proposed method is also discussed in this paper. The experimental results and the security analysis of the proposed method are given to validate the feasibility and robustness of the proposed method. The statistical analysis like histogram, correlation, entropy analysis, and randomness test confirm the robustness of the proposed method against statistical attacks. The experimental results also show that the proposed method is resistant to a brute-force attack. The proposed method has the ability to resist the occlusion attack, differential attack, and Gaussian random noise attack.