Abstract
Recently, several cryptosystems based on chaos have been proposed. Nevertheless, most of them hinder the system performance, security, and suffer from the small key space problem. This paper introduces an efficient symmetric encryption scheme for secure digital images based on a cyclic elliptic curve and chaotic system that can overcome these disadvantages. The cipher encrypts 256-bit of plainimage to 256-bit of cipherimage within eight 32-bit registers. The scheme generates pseudorandom bit sequences for round keys based on a piecewise nonlinear chaotic map. Then, the generated sequences are mixed with the key sequences derived from the cyclic elliptic curve points. Results of statistical and differential analysis demonstrate that the proposed algorithm has adequate security for the confidentiality of digital images. Furthermore, it has key sensitivity together with a large key space and the encryption is fast compared to other competitive algorithms.