Research On Multi-Image Encryption Technology Based On Computational Ghost Imaging

Computational Ghost Imaging(CGI)is a novel optical imaging technique.It uses active illumination to obtain spatial information of the target objects and reconstruct images by a computational means.During the measuring process,the object is encoded into one-dimensional(1D)real number sequence via a series of structured patterns,which dramatically reduces the amount of data.From the perspective of cryptography,the projected structured patterns can be taken as the security key,and the bucket detector collected data as the ciphertext.CGI naturally has the attribute of encrypting the imaged object.Due to the above advantages,CGI has been widely used in the field of optical information security.However,the conventional CGI-based encryption system has some limitations such as low measurement efficiency and poor reconstruction quality when encrypting multiple images.In addition,how to distribute keys rationally without crosstalk and security risks in a multi-user scenario is also an urgent issue that needs to be addressed.Therefore,this paper proposes two kinds of multi-image encryption schemes based on CGI system.(1)A multi-image encryption scheme based on binarized computational ghost imaging is proposed.Based on the feature that CGI is highly tolerant to deviations of ciphertext.Firstly,the intensity templates for projection are filtered according to certain rules,and then the secret images are encrypted by CGI,so that the binarization results of the ciphertext data are consistent,and the encryption of multiple images is completed.In the decryption process,the corresponding plaintext images can be recovered by decrypting the public ciphertext using different keys.In a multi-user application scenario,the scheme can share the public ciphertext with all users and design a unique key for each user to reconstruct his\her own secret image.This avoids mutual extraction between users and facilitates the distribution and management of keys in multi-user applications.Simulation results show that the scheme is feasible and has high encryption capacity and good robustness.(2)A multi-image encryption scheme based on Hadamard modulation computational ghost imaging is proposed.First of all,all secret images are encrypted by an initial Hadamard matrix,and the order of the ciphertext data is rearranged according to the numerical size of the public ciphertext.In the process of decryption,the authorized user transforms the Hadamard matrix according to the index key to generate the decryption key,and then completes the decryption through the reconstruction algorithm.Compared with the traditional computational ghost image encryption scheme based on random modulation,this scheme uses orthogonal modulation and takes the projection sequence of Hadamard basis as the security key,which not only compresses the key data,but also improves the reconstruction quality of the encrypted images.In addition,the scheme effectively suppresses the crosstalk noise in multi-user applications,and there is no mutual superposition in the decryption results even when encrypting some similar images.The feasibility and effectiveness of the scheme are verified by a series of numerical simulations.