MULTI-IMAGE HYBRID ENCRYPTION ALGORITHM BASED ON PIXEL SUBSTITUTION AND GENE THEORY

Abstract

A hybrid encryption scheme for multi-image is proposed in this paper, which can encrypt different types and different sizes of images simultaneously. First, the order of the discrete map is extended from integer order to unequal fractional order. By choosing suitable parameters, the map exhibits chaotic behavior, and using the map for the designed image encryption system can enlarge the key space of the cryptosystem. Then, the plain images are pixel substituted. The chaotic sequences produced from the unequal fractional-order discrete map are shaped and sorted; the index sequences generated by the sorting are used to replace plain image pixels. After plain image pixels are replaced, DNA encoding, selective diffusion, and gene exchange are performed. The statistical properties of the images are masked by the diffusion algorithm. Finally, simulation experiments and security test results show that the designed multi-image hybrid encryption algorithm is effective and secure.