Quantum Image Steganography Protocol Based on Quantum Image Expansion and Grover Search Algorithm

Quantum image steganography is one of the important research branches of quantum secure communications. In this paper, a large payload quantum image steganography protocol based on quantum image expansion and the Grover search algorithm is proposed. The new algorithm adopts quantum log-polar image (QUALPI) representation to prepare the quantum image before introducing a quantum expansion technique to form the superposition of multiple image copies with the same size angle difference as the carrier. Then, it embeds a secret message into one quantum image copy with a specific rotation angle encoded. In order to accurately extract the secret message embedded, the Grover search algorithm is used to locate the correct quantum image copy. Based on the quantum uncertainty and quantum non-cloning theorems, the new algorithm can not only achieve good imperceptibility and security but also large payload due to the algorithm's good coding scalability. The experimental results by performing MATLAB simulation prove the conclusions.