Edinburgh Napier University

  In today's digital world, securing the multimedia data, especially images transmitted over unsecure networks, is critically important. In this paper, a novel chaos-based image encryption algorithm is proposed, which utilises dynamic salt injection, hybrid chaotic maps and a dual operation substitution method to protect the image from digital attacks. The dynamic salt injection process creates a unique salt for each encryption instance ensuring that even identical images result in distinct hashes. The dual operation substitution serves as a pixel-level confusion technique which ensures that all identical pixels are replaced by distinct values even if same s-box value is selected. The unique diffusion-confusion components of the proposed scheme make it a secure yet lightweight scheme. Extensive security evaluation shows the effectiveness of the proposed scheme in achieving an entropy of 7.99 and a correlation of 0.005. Moreover, the equally distributed histograms and correlation plots depict the highest level of randomness achieved by the proposed encryption scheme. These results, along with other statistical security parameters, such as homogeneity, energy, and contrast validate the effectiveness of the proposed encryption scheme.