Research On Quantum Representation And Encryption Algorithm Of Color Digital Image

Information security is an indispensable part of national security.Quantum information security,especially quantum image information security,is an important research problem in quantum information age.Quantum image encryption is a hotspot in the research of quantum image information security protection technology and it has become an important part of quantum information security.Therefore,the research on quantum image encryption algorithm is of great significance.This paper studies recent developments of quantum image representation and quantum image encryption algorithm.The evaluation system of quantum image cryptosystem in theory is established for the first time,which must have validity,reliability and security simultaneously.The quantum image representation and its influence on the performance of encryption algorithm are analyzed.For example,the use of quantum state's phase encoding color information causes the cryptosystem to need transmit and receive massive encrypted quantum images during decryption process,and can not accurately recover the original image through limited number of measurements,only the probability value of color information can be obtained.Such encoding form decreases the reliability of cryptosystem and leads to the validity of cryptosystem can not be verified in quantum domain.Besides,the existing representation model which encodes color information by using quantum state's basis state and the corresponding encryption algorithm can accurately retrieve original image but stored procedure requires more entangled qubits and hence leads to more entangled qubits resources are consumed when storing color digital image in quantum computer and the corresponding cryptosystem can not be verified in quantum domain.To address the above problems,this paper studies quantum representation and encryption algorithm of color digital image,establishes the quantum color image representation model with high storage efficiency and accurate retrieval of original image,and proposes the quantum color image encryption algorithm with validity,reliability and security simultaneously.Specific contents are as follows:The right cyclic shift operator of existing NCQI(A Novel Quantum Representation for Color Digital Images)quantum color image representation model and the corresponding implementation circuit are studied.By combining right cyclic shift operator and XORoperator,an NCQI quantum color image encryption algorithm which can accurately retrieve the original image through limited number of measurements is proposed.For the first time,the process and circuit of verifying validity of proposed cryptosystem in quantum domain are given.The cryptosystem only needs to transmit and receive one encrypted quantum image,which has one time transmission and reception reliability.It solves the problem that original image can not be recovered accurately through limited number of measurements by using current quantum image encryption algorithm.Focus on the problem that more qubit resources are consumed to store a color digital image with current quantum representation model,a quantum color image representation model QRCI(Quantum Representation Model of Color Digital Image)which independently encodes bit-plane sequence information is established.This model represents a color digital image as an entangled quantum state generated by the superposition of partial computational basis states(1/8 of the total computational basis states).Compared with the existing NCQI representation model,QRCI representation model significantly reduces the number of entangled qubits required for storing a color digital image.QRCI representaion model has obvious storage advantages under the premise that the preparation of entangled state with multiple qubits faces great challenges.The preparation and accurate retrieval process of QRCI are given.The basic image processing operators based on QRCI and NCQI are compared to illustrate the flexibility of image processing operator of QRCI representation.Besides showing the superiority of the model itself,it lays a foundation for further researching the security protection technology of quantum multiple color images based on QRCI representation method.A quantum representation model DQRCI(Double Quantum Color Images Representation Model)which jointly stores double color digital images' information is established and a DQRCI quantum double color images encryption algorithm with interaction between color information of double images is proposed.DQRCI representation model represents double color digital images as an entangled quantum state generated by the superposition of partial computational basis states(1/64 of the total computational basis states).When encoding double color digital images with the same size and color depth,DQRCI representation model omits the expression of bit-plane sequence and pixel position of one of the two images,it further improves the storage efficiency.Based on the encoding characteristics of DQRCI,the operator which can fuse the color information of double images is constructed and the encryption of double color images is realizedby using fusion operator and XOR operator.The interaction between color information of double images increases the security of cryptosystem.The proposed encryption algorithm only needs to receive a complete encrypted quantum image and can accurately retrieve double original images through limited number of measurements,and it also can be verified in quantum domain.