Spatiotemporal chaos in globally coupled NCA map lattices using 3-D Arnold cat map for digital image encryption

In recent years, owing to the rapid growth of multimedia data transmission over the Internet, security is an important concern in the transmission and storage of digital images. Encryption is one of the most efficient and common practice to uplift image security. Many approaches for image encryption have been introduced including image encryption using chaotic sequences. Recently, the Coupled Map Lattices (CML) based Spatiotemporal Chaotic (STC) system has attracted much attention in the image encryption field. This paper introduces a new scheme for image encryption based on a novel spatiotemporal chaotic system by defining nonlinear dynamics in the Globally Coupled Map Lattice (GCML) using non-neighbourhood coupling. The proposed spatiotemporal chaotic system employs 3D Arnold Cat Map to couple four Nonlinear Chaotic Algorithm (NCA) maps for generating a pseudo random sequence which satisfies uniform distribution, ideal nonlinearity and zero cross-correlation to achieve higher level of security. The image encryption algorithm uses the chaotic sequence generated by one of the NCA map to permute the pixels of the image. Finally, the shuffled image is diffused using the constructed spatiotemporal chaotic sequence. The experimental outcomes reveal that the proposed spatiotemporal system is of high key sensitivity and with large key space. The results obtained from statistical analysis and key sensitivity tests illustrate that the proposed image encryption scheme is secure enough to resist the brute-force attack, entropy attack, statistical attack, differential attacks, chosen-plaintext attack and known-plaintext attack and thus provides an efficient and secure way for real-time image encryption and transmission.