Edinburgh Napier University

  In this digital era, ensuring the security of data transmission is critically important. Digital data, especially image data, needs to be secured against unauthorized access. In this regards, this paper presents a robust image encryption scheme named as VisCrypt. VisCrypt introduces a novel key generation and block permutation technique with visual cryptography to effectively encrypt the input images. The proposed scheme utilizes a diffusion-confusion image encryption architecture. The diffusion phase consists of novel key generation and block permutation techniques. The proposed key generation module utilizes hyper-chaotic maps with nonlinear dynamical behavior to generate random sequences that undergo spiral permutations to generate complex and unpredictable keys. Moreover, in the novel block permutation technique the image is decomposed into four equalsize blocks where each block is permuted using the generated permutation keys. Furthermore, in the confusion phase, a modified dynamic substitution process is applied on the permuted images and after substitution, the final encrypted images in visually concealed to add extra layer of security. Extensive security analysis validates the effectiveness of proposed scheme by exhibiting ideal results for information entropy, correlation, homogeneity, contrast, and energy.