A Quantum Based Encryption Scheme for Image Encryption

Abstract

As the use of digital communication accelerates, the need for robust and highly secure image protection methods has become important. Traditional encryption algorithms like AES and DES, effective for text, are often not suited for digital images due to their inherent data redundancy and high inter-pixel correlation. To address these limitations, this paper introduces a novel quantum-based image encryption strategy that merges quantum chaotic dynamics with a multi-stage confusion and diffusion architecture. The core of this system employs a Quantum Logistic Map (QLM) as the key generator. By harnessing the QLM's complex nonlinear behaviour and extreme sensitivity to initial parameters, we can produce highly unpredictable key sequences. The encryption algorithm itself is executed in three distinct phases: substitution, permutation, and diffusion. In substitution, pixel intensity values are first transformed using a dynamic Vigenère cipher, which is controlled by keys generated from the QLM. Permutation phase uses an RC4-driven random sequence to rearrange pixel positions, providing strong defence against both statistical and differential attacks. The final stage of diffusion applies a bitwise XOR operation, guided by quantum-derived keys, to effectively propagate small changes in the original image across the entire ciphertext. This combined methodology maximizes the system's randomness and effectively neutralizes any correlation between adjacent pixels. We conducted an experimental evaluation on a diverse set of standard test images to assess the scheme's security and performance. The results confirmed successful encryption with no visual data leakage, indicated by a high Peak Signal-to-Noise Ratio (PSNR). Correlation coefficients in the encrypted images approached zero, verifying effective de-correlation. The system also demonstrated powerful resistance to differential attacks, achieving a Number of Pixels Change Rate (NPCR) greater than 99.60% and a Unified Average Changing Intensity (UACI) value over 33.33%. Furthermore, the entropy values of the encrypted images neared the ideal 7.999 bits per pixel, indicating a near-perfect distribution of grey levels. The proposed quantum-based scheme exhibits a large key space and high key sensitivity due to its reliance on the QLM. Its high randomness, structural simplicity, and capacity for parallelization make this approach a promising solution for secure image transmission in various multimedia-dependent sectors.