Quantum image encryption (QIE) loads a digital image into qubits and ciphers it with unitary circuits, usually keyed by chaotic maps, quantum walks or quantum random numbers. This review follows the field from an early geometric-transformation scheme (2013) to designs executed on 127-qubit IBM processors (2025). We organise the literature by image representation (FRQI, NEQR, amplitude encoding), confusion and diffusion mechanism, key source and validation level, and we compare recent schemes on entropy, NPCR, UACI, correlation and key space. Reported statistics sit close to their ideals almost everywhere; recent quantum-walk and chaos-based designs report NPCR of 99.6 to 99.97% and UACI of 33.5 to 33.9%, so these metrics no longer separate strong schemes from weak ones. Three gaps stand out. Most evidence comes from classical simulation. The secret usually sits in a classical key generator rather than in the quantum circuit. And loading an image into qubits, then reading it back, remains the main hardware bottleneck. Hybrid designs that distribute keys with BB84 and cipher the image classically offer the most deployable route today. We close with a research agenda: attack-based benchmarks, error-aware hardware validation, cheaper state preparation and explicit security definitions.
Quantum image encryption (QIE) loads a digital image into qubits and ciphers it with unitary circuits, usually keyed by chaotic maps, quantum walks or quantum random numbers. This review follows the field from an early geometric-transformation scheme (2013) to designs executed on 127-qubit IBM processors (2025). We organise the literature by image representation (FRQI, NEQR, amplitude encoding), confusion and diffusion mechanism, key source and validation level, and we compare recent schemes on entropy, NPCR, UACI, correlation and key space. Reported statistics sit close to their ideals almost everywhere; recent quantum-walk and chaos-based designs report NPCR of 99.6 to 99.97% and UACI of 33.5 to 33.9%, so these metrics no longer separate strong schemes from weak ones. Three gaps stand out. Most evidence comes from classical simulation. The secret usually sits in a classical key generator rather than in the quantum circuit. And loading an image into qubits, then reading it back, remains the main hardware bottleneck. Hybrid designs that distribute keys with BB84 and cipher the image classically offer the most deployable route today. We close with a research agenda: attack-based benchmarks, error-aware hardware validation, cheaper state preparation and explicit security definitions.
As the world is transitioning towards the quantum era, this research presents the Quantum Key Distribution Inspired Image Encryption (QKDIE) algorithm, an image encryption and decryption framework that leverages the BB84 quantum key distribution (QKD) protocol to enhance the security of image transmission. BB84 ensures secure key exchange through the quantum bit error rate (QBER) monitoring. A QBER of approximately 1.0% was consistently achieved across all the experiments and well below the 11% security abort threshold. The BB84 sifted key is used to derive a 256-bit ChaCha20 stream cipher key via SHA-256, providing formally IND-CPA secure encryption with a unique nonce per session. The encryption pipeline implements four successive layers: Fisher-Yates pixel permutation for spatial scrambling, a key-dependent nonlinear S-box substitution for per-pixel confusion, an invertible CBC-style row-column diffusion layer for inter-pixel avalanche propagation, and ChaCha20 stream encryption for quantum seeded bitwise transformation. The proposed method is evaluated through cryptographic security metrics including UACI, NPCR, Shannon Entropy, pixel correlation, chi-square uniformity test, avalanche effect, and known-plaintext attack simulation, alongside decryption fidelity metrics including MSE, PSNR, SSIM, and NIQE. Experimental results across four test images demonstrate UACI values of 33.46% – 36.59% , NPCR values of 99.59% – 99.63% , Shannon entropy of 7.9968–7.9995 bits per pixel, and near-zero pixel correlation in all spatial directions. All four images passed the chi-square uniformity test (values 217.77–283.94, critical value 293.25). The avalanche test confirmed 99.60% – 99.61% pixel change rate and 50.01% – 50.05% bit-level change rate with a single-bit key perturbation, satisfying the strict avalanche criterion. KPA simulation confirmed keystream independence across sessions ( 47.27% – 51.95% bit match, indistinguishable from random chance). Perfect decryption was achieved in all cases (MSE =0 ) which validates the reliability of the proposed QKDIE framework.
In the rapidly evolving landscape of cybersecurity, traditional cryptographic systems are increasingly vulnerable to attacks, including brute-force, side-channel, man-in-the-middle, replay, and ransomware attacks, highlight the limitations of classical encryption techniques. Quantum cryptography leverages the no-cloning theorem and the properties of quantum states to establish fundamentally secure communication protocols with intrinsic eavesdropping detection capabilities. This security framework provides information-theoretic protection beyond the mathematical assumptions underlying conventional cryptographic systems. Quantum image security has evolved into two major paradigms: Quantum Key Distribution (QKD) and Quantum Secure Direct Communication (QSDC). Although recent surveys have reviewed both approaches chronologically, they have not systematically analysed their security thresholds The objective of this paper proposes a three-axis taxonomy of QSDC protocols, classifying them by quantum resource type, physical transmission channel, and device trust model. Furthermore, it presents a comparative performance analysis of QKD employing a hyperchaotic cipher over QSDC channels across seven quantum image representations, including FRQI, NEQR, GQIR, and MCQI. The analysis shows that QKD-seeded schemes achieve efficient key distribution, whereas pixel-level security remains dependent on cipher complexity. In contrast, QSDC provides end-to-end security governed by quantum mechanical principles; hyperentangled carriers achieve an eavesdropping detection probability of 0.875 compared with 0.5 for conventional two-step protocols, although communication throughput remains a limiting factor. Based on these findings, this review outlines future research directions, including QSDC-specific quantum repeaters for continental-scale deployment, hyperentangled carriers supporting up to 12 bits per photon pair compatible with NEQR’s 8-bit encoding, and machine-learning-assisted management of hybrid fiber–free-space quantum communication networks.
Since their introduction, numerous quantum image encryption methods have been developed. As we shall demonstrate, protecting visual information against classical and quantum threats depends on representations. In this paper, we identify the essential components of quantum encryption algorithms and explain a variety of quantum image representations with different levels of qubit efficiency, computational complexity, and security. The paper also explores the favourable and unfavourable aspects of hybrid, chaos-based, quantum transform-based, and DNA-based quantum image encryption schemes. The security analysis focuses on noise tolerance and scalability. This involves aspects such as key space size, resistance to various attacks, and calculation efficiency. Meanwhile, potential areas for investigation include robust algorithms, hybrid systems and reducing decoding errors. We also address the implementation difficulties involved, including the necessary hardware and decoding error reduction. Classical and quantum techniques, as well as more advanced quantum equipment, are considered too. The evaluation calls for uniform policies and realistic responses and emphasises how quantum image encryption could transform information security in the quantum era. and realistic answers and highlights how quantum image encryption may change information safety within the quantum generation.
Since their introduction, numerous quantum image encryption methods have been developed. As we shall demonstrate, protecting visual information against classical and quantum threats depends on representations. In this paper, we identify the essential components of quantum encryption algorithms and explain a variety of quantum image representations with different levels of qubit efficiency, computational complexity, and security. The paper also explores the favourable and unfavourable aspects of hybrid, chaos-based, quantum transform-based, and DNA-based quantum image encryption schemes. The security analysis focuses on noise tolerance and scalability. This involves aspects such as key space size, resistance to various attacks, and calculation efficiency. Meanwhile, potential areas for investigation include robust algorithms, hybrid systems and reducing decoding errors. We also address the implementation difficulties involved, including the necessary hardware and decoding error reduction. Classical and quantum techniques, as well as more advanced quantum equipment, are considered too. The evaluation calls for uniform policies and realistic responses and emphasises how quantum image encryption could transform information security in the quantum era. and realistic answers and highlights how quantum image encryption may change information safety within the quantum generation.
The rapid growth in the storage and transmission of visual data across communication, sensing, and decision-making systems requires image encryption methods that are both computationally efficient and resilient against quantum-enabled adversaries. Classical chaotic encryption offers desirable properties such as sensitivity, unpredictability, and large key spaces, but its practical use is limited by restricted chaotic ranges, and conventional confusion–diffusion mechanisms often fail to eliminate structural redundancies in images. This thesis furthers the field by developing novel chaotic and gate-efficient quantum image encryption architectures. First, it introduces a new cosine-modulated polynomial chaotic map and validates its dynamical and statistical suitability for cryptographic key generation. Second, it designs lightweight yet effective chaotic primitives, including the Single-Round Single S-Box (SRSS) confusion mechanism and the featureaware diffusion scheme (PermutEx) that address the limitations in breaking correlation and maintaining efficiency. Third, these components are integrated into a complete endto- end chaos-based encryption framework that combines feature-driven segmentation, adaptive permutation, and dynamic confusion, demonstrating strong security across entropy, correlation, and differential metrics. Finally, the thesis advances two quantum image encryption architectures, i.e., a chaos-enhanced quantum image encryption framework that strengthens quantum confusion and diffusion mechanisms, and a gate-efficient architecture that reduces circuit depth and multi-qubit operations while retaining robust security. The proposed architectures achieve improved computational efficiency compared to existing chaos-based and quantum image encryption techniques, by reducing redundant operations, minimising circuit depth, and enabling lightweight yet effective confusion-diffusion processes. Consequently, this thesis provides a way forward for advancing image encryption by integrating chaotic and quantum approaches, offering practical steps for protecting visual data in the post-quantum era.
Quantum processors enable real-time image processing and provide no-cloning theorem-based security for quantum image encryption. Most classical image encryption methods cannot be directly applied to quantum images due to the implementation complexity of using the quantum circuit, and most existing secure quantum image encryption methods are designed for grayscale images. Thus, we propose a quantum color image encryption method. The proposed method is designed for the existing efficient-storage quantum representation model of color digital image (QRCI) representation. The proposed QRCI-based encryption method benefits from a small number of qubits in total (i.e., 2n+7 qubits), where the QRCI representation uses 2n+6 qubits and two pseudorandom number sequences use only 1 qubit. The improved chaos-based pseudorandom number generator strikes a balance between reduced computation and security level. The two-round exclusive-OR-based diffusion method for quantum encryption significantly improves key sensitivity. Low gate costs are required. Experimental results show that the proposed method outperforms state-of-the-art quantum color image encryption methods in terms of security measures. In addition, the number of qubits of the proposed quantum image encryption method is small (2n+7 qubits).