# Quantum Image Steganography Schemes for Data Hiding: A Survey
## 5 Conclusions  
In conclusion, this survey paper encompasses a discussion on the field of quantum steganography, specifically examining five sections from demonstrating the background of quantum image representation to interpreting and evaluating diverse methods for achieving image steganography. Approaches reviewed are listed below:  
1. Least significant qubit: uses the carrier image's least significant qubits to embed the needed secret qubits. 2. Turtle-shell-based matrix: secret message's qubits are encoded following a turtle-shell pattern. 3. Inverted pattern approach: compares and chooses the best sequence between the inverted and original stego image to generate a new advanced version. 4. Pixel value differencing: detects the appropriate number of bits to embed in each pixel by subtracting two successive pixels. 5. Quantum noisy channels effects: manipulates the effects of these channels on the bits during transfer. 6. Entanglement as a degree of freedom: concerned with photons as an entangled pair and utilizes quantum communication channels for it. 7. Quantum image scrambling: applies Hilbert scrambling protocol on a quantum media's fragment resulting in a hidden disordered output that is then transported to the receiver. 8. Double-layer matrix coding: attains steganography by employing both Hamming and paper codes. 9. Interpolation-sased scheme: determines the number of bits to embed in each pixel by comparing differences between the upscaled and original images after using the interpolation algorithm. 10. Controlled alternate quantum walks protocol: considered as random walks protocol's quantum substitute; a random location is chosen by a probability distribution matrix. 11. Quantum EMD protocol: implements the odd base carrying system to obtain embedding each media's piece's qubit into a cover. One of the many limitations showcased in authors' works is the use of spatial and transform domains, since although the spatial domain offers an easy implementation, it still demonstrated a low rate of robustness. Conversely, the transform domains exhibited a high complexity and a limited image embedding space despite its minimal bit error rate and robustness. Another limitation is that a lot of the schemes were implemented using simulations instead of real quantum computers due to their general inaccessibility to the public. Furthermore, one of the inconveniences that we faced while writing this paper is that there were not enough research papers in the quantum steganography branch since it is still considered an inchoate field. Moreover, the concept of quantum computing is not yet available to the general public. Due to that, we faced plenty of difficulties in becoming familiar with quantum-related concepts. On the other hand, diverse future work ideas were suggested by multiple researchers to enhance the concept of image steganography. For example, [PERSON] advised improving the least significant qubit method by including a reset operation for the qubit. Additionally, to convey outstanding image steganography in the medical sector, researchers working with the controlled alternate quantum walks protocol proposed possible applications to work on modern computing models. For our future work, and as authors and researchers in the field, we are starting our steps towards integrating the concept of oblivious transfer in the process of attaining quantum image steganography, which combines cryptography using various protocols along with image steganography schemes in the process of data embedding, thus, increasing the security of hidden information. Writing--original draft, M.A. ([PERSON]), M.A. ([PERSON]), D.A., R.S. and R.A.; Writing--review & editing, N.M.-A., N.N. and M.A. ([PERSON]). All authors have read and agreed to the published version of the manuscript. The authors would like to thank SAUDI ARAMCO Cybersecurity Chair, Imam Abdulrahman Bin Faisal University for funding this project. Not applicable. Authors would like to thank anonymous reviewers and for the excellent feedback on initial versions of the paper.