Dynamic Multi-Layered Image Encryption scheme using User Driven Chaotic Sequences

Abstract With technological advances, sharing sensitive information, such as multimedia data, especially images, is common. To protect the integrity of such data, advanced encryption algorithms are utmost necessary. The proposed encryption scheme introduces a novel approach that capitalizes on the distinct characteristics of users' authenticated usernames to dictate the sequence in which image blocks are encrypted. The methodology encompasses two key strategies. Initially, a set of four individual chaotic maps - Sin, Chebyshev, Logistic, and Gaussian - are employed for encryption. Also, the image blocks are encrypted with a novel 4D chaotic map. The process begins with segmenting an N×N×3 color image into its red, blue, and green constituents, each of size N×N. These constituents are further subdivided into four arrays, each sized (4×4) × (N/4) × (N/4). The encryption process for various image bands is based on the use of chaotic sequences generated by schemes 1 and 2. These resulting sequences serve as the fundamental encryption keys, guiding a variety of processes including both confusion and diffusion. The proposed encryption schemes, Scheme 1 and Scheme 2 were rigorously evaluated through extensive simulations, comparing their performance with a traditional algorithm. Both procedures demonstrated robustness against statistical analysis differential attacks and showcased NPCR and UACI values closely approximating ideal standards of 99.6 and 33.4, respectively. Notably, Scheme 2, employing the proposed 4D map, outperformed Scheme 1, which used four different chaotic maps, particularly in terms of NPCR and UACI. The schemes exhibited a significant key space of 2540, rendering decryption infeasible within an astronomical time frame of 9.449 × 10130 years. Further, entropy and correlation analysis validation revealed values close to 7.99 and 0, aligning with traditional algorithms' values. Additionally, pixel distribution analyses indicated uniformity along horizontal, vertical, and diagonal directions. The paper introduces an innovative encryption approach that capitalizes on user-specific characteristics and demonstrates superior security and performance compared to conventional methods.