A novel image encryption scheme based on elliptic curves and coupled map lattices

The security of digital images has become the main concern due to the rapid rise in the sharing of data over the Internet and open networks. Recently many image cryptosystems are introduced to secretly share data but have some efficiency issues and drawbacks. Couple map lattices (CMLs) chaotic-systems and elliptic curves (ECs) are widely used in cryptography due to their long period and random behavior. A novel and secure image encryption algorithm based on ECs and CMLs is proposed for the real-time transmission of images with the aim to overcome the shortcomings of traditional encryption algorithms. The encryption procedure is mainly divided into two steps. In the first step, EC-based pseudo-random-numbers are used to create diffusion in the plain-image. In the second step, a substitution-box generator based on ECs and CMLs is designed to create confusion in the diffused image. The proposed encryption scheme has a large keyspace and is robust against the brute-force attacks. The use of a CMLs chaotic-system makes the encryption algorithm secure against the known-plaintext attack. The computation time of the newly constructed scheme is very low as it takes only 0.641 s to encrypt an image of size 256 x 256. The outcome of the experimental and statistical analysis shows that the proposed encryption algorithm is highly secure and can outperform some state-of-the-art schemes.