Dynamic Multi-Layered Image Encryption Scheme Using User Driven Chaotic Sequences

The paper introduces a novel approach that leverages the unique characteristics of users’ authenticated usernames to determine the sequence in which image blocks are encrypted. This methodology adopts two main strategies: first, it utilizes four distinct chaotic maps—Sine, Chebyshev, Logistic, and Gaussian—for encryption; second, it encrypts image blocks using a newly proposed 4D chaotic map. The process begins with the segmentation of an N×N×3 color image into its red, blue, and green components, each of size N×N. The image components are further subdivided into four arrays, each sized (4 × 4) × (N/4) × (N/4). The chaotic sequences generated by Schemes 1 and 2 serve as crucial encryption keys, guiding the confusion and diffusion processes and facilitating the encryption of various image bands. Using comprehensive simulations, the proposed encryption schemes, Schemes 1 and 2, were carefully assessed and contrasted with a conventional method. It is found that even though both the schemes outperformed against statistical analysis differential attacks, notably, Scheme 2, with the proposed 4D map, performed better than Scheme 1, especially with respect to UACI and NPCR. Also, the proposed methodology has a larger key space, thereby making decryption highly impossible within speculated timeframe. Also the validation of the proposed methodology with entropy and correlation analysis produced results in accordance with accepted methods while homogeneity in the horizontal, vertical, and diagonal directions was verified using pixel distribution analysis. The research work thus presents a novel encryption technique that surpasses conventional techniques in terms of security and performance while using user-specific attributes.