A Chaotic Image Encryption Scheme Using Novel Geometric Block Permutation and Dynamic Substitution

2025-03-13

AI Summary

To address security vulnerabilities arising from unauthorized access during digital image transmission and storage, this paper proposes a chaos-based confusion-diffusion image encryption framework. The method innovatively employs four geometric patterns—L-shaped, U-shaped, square, and inverted-U-shaped—for block-level pixel extraction and permutation, combined with bitwise XOR operations driven by a 2D Hénon chaotic map and an adaptive dynamic S-box substitution mechanism. Experimental results demonstrate that the encrypted images achieve an information entropy of 7.9974 and exhibit extremely low inter-pixel correlations—below 0.0014 in horizontal, vertical, and diagonal directions—significantly outperforming existing approaches. The scheme further exhibits strong resistance against statistical and differential attacks while maintaining high computational efficiency, thereby achieving an effective balance between security and performance.

Technology Category

• Computer Vision: Adversarial Attacks & Robustness
• Machine Learning: Privacy
• Search and Optimization: Distributed Search

Application Category

• Security and Privacy: Applications of cryptography
• Web Mining and Content Analysis: Content-based information diffusion
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

In this digital era, ensuring the security of digital data during transmission and storage is crucial. Digital data, particularly image data, needs to be protected against unauthorized access. To address this, this paper presents a novel image encryption scheme based on a confusion diffusion architecture. The diffusion module introduces a novel geometric block permutation technique, which effectively scrambles the pixels based on geometric shape extraction of pixels. The image is converted into four blocks, and pixels are extracted from these blocks using L-shape, U-shape, square-shape, and inverted U-shape patterns for each block, respectively. This robust extraction and permutation effectively disrupts the correlation within the image. Furthermore, the confusion module utilises bit-XOR and dynamic substitution techniques. For the bit-XOR operation, 2D Henon map has been utilised to generate a chaotic seed matrix, which is bit-XORed with the scrambled image. The resultant image then undergoes the dynamic substitution process to complete confusion phase. A statistical security analysis demonstrates the superior security of the proposed scheme, with being high uncertainty and unpredictability, achieving an entropy of 7.9974 and a correlation coefficient of 0.0014. These results validate the proposed scheme's effectiveness in securing digital images.

Problem

• Develops a novel image encryption scheme for secure data transmission and storage.
• Introduces geometric block permutation to disrupt image pixel correlation.
• Utilizes chaotic seed matrix and dynamic substitution for enhanced image security.

Innovation

• Geometric block permutation for pixel scrambling
• Dynamic substitution with bit-XOR operations
• Chaotic seed matrix using 2D Henon map