X-Cross: Image Encryption Featuring Novel Dual-Layer Block Permutation and Dynamic Substitution Techniques

2025-03-13

AI Summary

To address security threats to digital images during transmission and storage, this paper proposes the X-Cross image encryption algorithm. The method integrates a two-layer block permutation—comprising bit-level IBT permutation and a novel X-cross pixel permutation—with a key-driven dynamic S-box confusion mechanism. A strong nonlinear 2D chaotic map generates dynamic keys, while a Bit-Extraction mechanism enables key-sensitive bit-level rearrangement, effectively eliminating statistical redundancy and structural features. Experimental results demonstrate an information entropy of 7.9993, adjacent-pixel correlation coefficients below 0.002, and robust resistance against differential and statistical attacks—achieving ideal security metrics. The core contributions include: (i) the first two-layer block permutation architecture; (ii) the X-cross pixel permutation algorithm; and (iii) a synergistic chaotic–bit-extraction key generation mechanism.

Technology Category

• Computer Vision: Adversarial Attacks & Robustness
• Humans and AI: Explainable AI (XAI) for Human Understanding
• Search and Optimization: Algorithm Configuration

Application Category

• Security and Privacy: Applications of cryptography
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

In this digital age, ensuring the security of digital data, especially the image data is critically important. Image encryption plays an important role in securing the online transmission/storage of images from unauthorized access. In this regard, this paper presents a novel diffusion-confusion-based image encryption algorithm named as X-CROSS. The diffusion phase involves a dual-layer block permutation. It involves a bit-level permutation termed Inter-Bit Transference (IBT) using a Bit-Extraction key, and pixel permutation with a unique X-crosspermutation algorithm to effectively scramble the pixels within an image. The proposed algorithm utilizes a resilient 2D chaotic map with non-linear dynamical behavior, assisting in generating complex Extraction Keys. After the permutation phase, the confusion phase proceeds with a dynamic substitution technique on the permuted images, establishing the final encryption layer. This combination of novel permutation and confusion results in the removal of the image's inherent patterns and increases its resistance to cyber-attacks. The close to ideal statistical security results for information entropy, correlation, homogeneity, contrast, and energy validate the proposed scheme's effectiveness in hiding the information within the image.

Problem

• Develops a novel image encryption algorithm for secure data transmission.
• Introduces dual-layer block permutation and dynamic substitution techniques.
• Enhances resistance to cyber-attacks by removing image patterns.

Innovation

• Dual-layer block permutation for image scrambling
• Dynamic substitution technique for final encryption
• 2D chaotic map for complex key generation