Research On Optical Image Encryption Based On Computational Ghost Imaging

With the rapid development of information technology,a large number of information will be converted into digital data to be transmitted through the network.In this process,ensuring the security of data becomes more and more important.Cryptography is the core technology to ensure information security,it can hide information to ensure the confidentiality of information.Since Refregier proposed double random phase encryption technology based on 4f system in 1995,optical image encryption technology has developed rapidly due to its advantages of fast encryption speed and multi-dimensional coding.With the in-depth study of researchers,many optical encryption methods have been proposed one by one.Among them,the optical encryption system based on computational ghost imaging has been widely concerned because its ciphertext storage space is smaller than previous optical encryption methods.But computational ghost imaging also has some disadvantages.Computational ghost imaging is vulnerable to chosen plaintext attack because of the linear relationship between input and output.In order to improve the anti attack ability of computational ghost imaging,we propose plaintext-related ghost imaging encryption system.The main innovation of this system is that it can reduce the key storage space and improve the anti attack ability of the system.Based on the calculation of ghost imaging,we use logistic map and linear congruential method to realize the plaintext related ghost imaging encryption algorithm.Firstly,the first u pixels are extracted from the plaintext image,and the sum of the pixel values Xo of the u pixels is taken as the initial value of the linear congruence algorithm,and the initial random phase mask is generated by the linear congruential method.In the second step,the initial random phase mask is used as the initial value of logistic map,and then all the random phase masks are generated by Logistic map.Finally,the random phase masks were loaded into SLM of computational ghost imaging encryption system to realize plaintext related ghost imaging encryption.In this system,the dynamically updated random phase mask can make the system resist the chosen plaintext attack,and the parameter keys can replace the original tens of thousands of random phase mask keys,which can successfully reduce the key storage space.In order to further improve the encryption efficiency of plaintext related ghost imaging system,we propose a multi-image encryption system based on plaintext-related ghost imaging system.Firstly,plaintext images transformed by Arnold transform,and then Arnold transformed.images are combined into one by XOR operation.Finally,the combined XOR image is encrypted by plaintext related ghost image encryption system.Plaintext related ghost imaging encryption system uses parameter keys and plaintext information to generate random phase masks,so as to dynamically update the random phase masks,which can protect the information from the attack of chosen plaintext.Multiple images can be encrypted at the same time by XOR operation,so as to improve the encryption efficiency.Finally,in order to solve the problem of key storage management in plaintext-related ghost imaging system,we propose a hybrid encryption system based on plaintext correlation and elliptic curve encryption.When we use the plaintext related ghost imaging encryption system,we find that the parameter key Xo will change with each encryption.Although the parameter key is very small,frequent updates will bring inconvenience to the key storage management.In addition,the optical encryption system is a symmetric encryption system,so there are some shortcomings in the key security transmission.Therefore,based on the above problems,we propose a hybrid encryption scheme.In this system,the plaintext is encrypted by the plaintext related ghost imaging encryption system,and then the parameter key in the plaintext related ghost imaging is encrypted by elliptic curve algorithm,so that the user only needs to hold the private key of elliptic curve encryption to use the system successfully.Through the hybrid encryption system,we retain the advantages of plaintext related ghost imaging encryption system,and solve the problem of key storage and distribution.